e.4 * i , C ai~ 7.- 4 A * -j 4 r W 16 A pv it :,'I X f-.4 -rv %AN, 16 WJ-% Ar-, -A.. irI % ;rv,. .Le, if 41 r I - a i CONTENTS Page List of Tables and Figures........................................... 0001000a0aaa00a00003-5 Introduction.................................... Cold Climate in Alabama......... .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . . . . . . . . . . . ............... a07 Freeze Classification and Meteorological Conditions.... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ....7 Freeze Injuryto Plants .. .. .. .. .. ..... .... .. .. . .... .. . ... ....... .. ................ . .. ...... 8 Source of Data......................................................... 9 The Growing Season ............................................. 10 Freeze Probabilities.....................................................0*0110 Freeze Maps.........................................................*000*0000000006*0a000&a00a00011 Climatological Probabilities and Forecasts...................................... 11 References ............................................ 11 Appendix Table I .. .. .. .. .. .. .. .. ........................... 33 In formation contained herein is available to all without regard to race, color, or national origin. FIGURES Page 1. Locations of 74 Temperature Reporting Stations and 8 Climatic Divisions .............. ................. .. ............................................... 12 2. Average Length of the Growing Season (days) .......................................... 13 3. Mean Date of First 32 0 F Freeze in the Fall .................................................. .. 22 4. Dates in the Fall Before Which There Is a 20 Percent Chance of a 32 0 F Freeze ................... ........................ ................................. 23 5. Mean Date of Last 32 0 F Freeze in the Spring ................................................. 24 6. Dates in the Spring After Which There is a 20 percent chance of a 32 0 F freeze .............................................................................. 25 7. Mean Date of First 28 0 F Freeze in the Fall .................................................... 26 8. Dates in the Fall Before Which There Is a 20 percent chance of a 28 0 F Freeze ........... 0............................ 27 9. Mean Date of Last 28 0 F Freeze in the Spring .................................................. 28 10. Dates in Spring After Which There Is a 20 Percent Chance of a 28 0 F Freeze ................................................................................ 29 11. Probability of a 24 0 F Freeze or Colder Occurring Sometime During Cold Season ...................................................................... 30 12. Probability of a 20OF Freeze or Colder Occurring Sometime During Cold Season . ............................. 0................................... ,.. .. 31 13. Probability of a 16 0 F Freeze or Colder Occurring Sometime During Cold Season ........................................................................ 32 TABLES Cold Temperature Danger Points for Certain Fruits ............................................. 8 Critical Temperatures of the Blossoms and Young Fruits of Berries at Different Stages of Development .................................................. 9 Resistance of Crops to Freeze at Different Stages of Development ................................... 9 Station Location and Elevation ................................................................ 9-10 Freeze Data (32 0 F) .......................................................................... 14-15 Probability of Spring and Fall Temperature Thresholds ........................ .............. 15-21 Mean Day Number, Standard Deviation, and Probability of Temperature Occurrence ............................................................... 33-36 CLIMATE OF FREEZE IN ALABAMA Jere R. Gallup Agricultural Meteorologist INTRODUCTION T HE CLIMATE of freeze for any geographical area deter- mines what crops can be grown, the scheduling of planting, and the ending of harvest. Few climatic influences place greater constraints on agriculture or require more timely planning and decision-making by the farmer than the occurrence of freezing temperatures. The "growing season," often defined as the interval between the last and first occurrence of 32 degrees Farenheit, sets the climatic limitations within which the agriculturalist must work. He must give consideration to possible losses from a late freeze in the spring or the risk of a similar occurrence early in the fall. Vegetable and fruit growers are the most concerned with a freeze. However, some field crops such as cotton, corn, peanuts, and small grains may also be damaged or killed by unseasonal freezes. The use of climatology in operating a farm or any other weather sensitive business allows more precise judgement and reduces reliance on subjective appraisals about the future effects of weather. Familiarity with the cold season climate, therefore, can be important when evaluating long- term plans and decisions. For example, the probable dates of last spring or first fall freeze occurrence can be used to establish the normal chances that a freeze will follow a certain date in the spring or arrive before a particular date in the fall. The purpose of this publication is to-provide an analysis of freeze occurrence in Alabama. In addition to freeze proba- bilities, information about extreme dates of freeze occur- rence and average length of freeze-free period (growing season) is provided. COLD CLIMATE IN ALABAMA Winters in Alabama are relatively mild due to the State's southerly latitude and its proximity to the Gulf of Mexico. Severely cold weather seldom occurs. Even in the northern third of the State, temperatures of zero or lower are gener- ally rare and occur only when there is snow on the ground. Arctic air masses are often diverted eastward before pene- trating as far south as Alabama. Temperatures of 100 F. or less are usually reached only once in a season across central Alabama, and only on occasional years do temperatures reach the teens as far south as Mobile. Even during very cold outbreaks, southern states normally are spared the brunt of frigid temperatures. Also, at latitudes as far south as Ala- bama, longer days, a more vertical sun angle, and the greater uptake of warmth from the earth's surface help to rapidly modify the severity of cold air masses. The Gulf of Mexico affects the climate throughout Ala- bama during the winter months. Although cold air usually predominates, periodic swings to a southerly wind flow can bring mild and sometimes warm temperatures northward into the Tennessee Valley. For much of thetime, however, frontal systemsmoving through the State effectively limit the Gulf's influence from spreading very much north of coastal areas. More cloudiness over the north probably results in slower warming trends as well as increased chan- ces for icy conditions or snow. Sunshine is more the rule on the coastal plain where the Gulf has its strongest influence on temperatures. Even as far south as the Gulf Coast, how- ever, freezing temperatures will occur regularly during any winter season. Characteristic weather patterns during the early fall and late spring become most influential in determining the dis- tribution of growing seasons within Alabama. During these months, weaker systems of cold air fail to produce freezing temperatures as deeply southward into the State. Frontal systems often become positioned across the State separat- ing the milder Gulf currents from colder air to the north. An earlier fall freeze over northern areas may cut the growing season short, while on the coastal plain temperatures have only added a chill to the air. A late spring in the northeast- ern valleys may keep fruit buds from showing, while farther southward temperatures have not been cold enough to restrict bloom. Thus, freeze patterns evolve from north to south within the State as the seasons make their transitions. FREEZE CLASSIFICATION AND METEOROLOGICAL CONDITIONS Some distinction between the meanings of frost and freeze is needed with the day to day usage of these terms. Frost forms as a deposit of ice crystals on the ground and other surfaces which have cooled to below 32?F. The pro- cess involves the conversion of water vapor in the air directly to ice crystals while bypassing the intermediate liquid state. When air having a dew point below freezing is chilled to saturation, usually by contact with cold surfaces, frost often forms as a surface deposit. During frost condi- tions, air temperatures at standard observation height (5 feet above ground) often are above freezing. The term freeze applies to air temperatures at standard measurement height that have fallen to 32?F or lower. A freeze may be observed with or without the occurrence of frost. Freezing temperatures are usually classified according to the general severity levels at which agricultural crops and ornamental plants suffer damage when subjected to varying temperature ranges below 32 0 F. The severity of damage depends upon the characteristics of the given crop. Major damage to growing plants occurs within a broad range of temperatures below freezing. Some plants are killed by temperatures slightly below freezing while others may sur- vive at much lower temperatures. Freeze damage may range from injury to different plant parts to plant death. Crops have been classified as tender, semi-hardy, and hardy according to their general abilities to withstand low temperature. The severity of a freeze and its associated temperature may, therefore, be judged by how widespread the damage is within these categories of plant hardiness. In general, cool season, winter-hardy plants can survive much lower temperatures than warm season types. The following freeze classification has been adopted by agricultural meteorologists: Light Freeze. Air temperature ranges between 28 0 F and 32 0 F. Tender plants such as watermelons, tomatoes, beans, and peppers may be killed. There is little or no damage to most other plants. Moderate Freeze. Air temperature ranges between 25*F and 28 0 F. There is heavy damage to fruit blossoms and semi-hardy plants. Most plants suffer some damage with tender plants usually destroyed. Severe Freeze. Air temperature is 24 0 F or below. There is heavy damage to most plants. Annual plants are destroyed. Ground is usually frozen. A freeze may also be classified according to the atmos- pheric processes under which it occurs. The passage of cold frontal systems with strong northerly winds and rapidly falling temperatures are typical conditions during an advec- tive type freeze. Winds transport cold air having below freezing temperatures into a region where warmer air is being displaced. This results in temperatures falling to the freezing point in response to the arrival of progressively colder air. A radiation freeze develops under characteristically dif- ferent atmospheric conditions. In these situations cold, dry air becomes established over an area producing clear skies and light or calm winds. These conditions are suitable for a net loss 6f terrestrial heat energy outward through the earth's atmosphere. During the night, when the energy lost is not being replaced by solar radiation, the earth's surface and the layer of air above it cool steadily. If the air is suffi- ciently dry and potentially cold enough as the cooling pro- cess begins, temperatures may fall below freezing. Under radiation conditions, nighttime temperatures drop most rapidly within the shallow layer of air just above ground level. This can result in a more severe freeze for plants grown at field height and in low-lying areas. On such nights the colder, more dense air tends to accumulate and flow into lower pockets and valleys across the landscape. Such areas are more susceptible to radiation freeze. Environmental changes that result in more cloudiness or water vapor in the atmosphere may retard terrestrial radia- tion. Such conditions can prevent temperatures from low- ering to the freeze point. Wind movement also becomes important as a modifier of temperature if it is sufficient to cause mixing of the temperature stratified air above the surface. On a freeze night this may result in raising tempera- tures by a few degrees as the warmer air above is mixed with colder air near the surface. To some extent, air temperature will be modified by other environmental factors such as warm or damp soils, local water bodies, or differences in vegetative cover. FREEZE INJURY TO PLANTS Since resistance to freeze injury varies greatly among different kinds and varieties of plants, the farmer or home gardener should be familiar with the freeze characteristics of his particular crops. The temperatures that become criti- cal to a plant's survival are usually the basis for the planning and carrying out of freeze protection. They are also used for determining safe dates for planting field and vegetable crops through the use of freeze probability tables con- tained in this publication. Several meteorological factors increase a plant's suscep- tability to freeze damage. The amount of chilling necessary to produce damage depends on the duration of a critically low temperature. Plants are likely to survive temporary exposure to a damaging freeze that results in only minor injury to plant parts. However, when a plant issubjected to critical temperatures for any length of time, the plant usu- ally dies. The rate at which temperatures fall is often impor- tant when describing the effects of a freeze. With a sudden onset of freeze, some plants experience greater trauma and damage than would otherwise occur with slowly dropping temperatures, even though the same minimum tempera- ture levels may be reached in both cases. Desiccating winds that often accompany severe outbreaks of cold weather can also increase damage considerably. The temperature environment before freeze occurrence may either condition the plant to better withstand the effects of freeze or cause the plant to be more susceptible to freeze injury. Several days of unseasonably warm weather in the winter or early spring may cause perennials to come out of dormancy early and become especially vulnerable to freeze. Warm and wet conditions may stimulate new growth of tender vegetation which is later killed back with greater severity. On the other hand, a period of cool weather is likely to condition a plant to become more frost tolerant. A plant may develop its own natural protection from freeze in response to its temperature environment. For example, a cool spring usually results in slower plant growth and more frost resistant or woody tissue exposed to freezing tempera- tures. Fruit trees will delay bloom during an unseasonably cool spell. Fruit production reaches a critical stage for freeze dam- age during the bloom and fruiting period. Many fruits gage the beginning of their bloom by a sufficient accumulation of chill hours (hours the temperature is -< 45 0 F). When a sufficient number of chill hours are reached during dor- mancy, bloom will be triggered by a measured period of accumulated warm temperature. Unseasonal weather fluc- tuations in the winter or spring may complicate this timing of bloom so that it arrives while a significant freeze danger still exists. Critical temperatures during the bloom period for various fruit and berry crops are listed in tables 1 and 2 taken from Eichmeier et al. (1965). Table 1. Cold Temperature Danger Points for Certain Fruits Stage of development Petals 14-18 Glassy closed days Fruit green but Full Petal after stage visible bloom fall bloom Apple ........ Apricot ....... Blueberry ..... Grape ........ Peach ......... Pear .......... Plum ........ Red Tart (sour) Cherry ........ Stanley Prune.. Sweet Cherry OF 25-28 24-26 25 29-31 24-26 25-27 24-26 28-29 27-28 OF 28-30 26-28 26 29-31 26-28 28-30 26-28 26-28 28-30 25-27 28-30 25-27 28-30 OF 28-30 2628 26 29-31 26-28 28-30 28-30 28-30 28-30 28-30 28-30 28-30 27 29-31 28-30 28-30 28-30 28-30 28-30 28-30 [81 Table 2. Critical Temperatures of the Blossoms and Young Fruits of Berries at Different Stages of Development (Temperatures Are Approximate Only) Kind of Tight Balloon Full Green fruit bud bud bloom fruit OF 0 FOF OF Strawberries ... 22 28 31 28 Red rasp- berries..... 25 27 29 27 Black rasp- berries ...... 26 28 30 28 Resistance to freeze damage varies considerably among different vegetable and field crops. In table 3, adapted from Ventskevich (1961), 27 of these crops are classified accord- ing to their freeze resistance. Critical temperatures were based on the harmful effects of freeze that occurred during various stages of crop development. Table 3. Resistance of Crops to Freeze at Different Stages of Development (Harmful Temperatures'*F.) Crop Germination Flowering Fruiting Highest resistance to freeze Spring wheat........ 14-16 28-30 25-28 Oats............... 16-18 28-30 25-28 Barley ............. 17-19 28-30 25-28 Peas ............... 17-19 26-28 25-27 Resistance to freeze Lupine............. 17-21 .25-27 25-27 Spring vetch........ 19-21 25-27 25-28 Beans.............. 21-23 26-28 25-27 Sunflower........... 21-23 26-28 26-28 Safflower........... 21-25 26-28 25-27 Beets ............. 19-21 26-28 Carrot ............ 19-21 Turnip............. 19-21 Medium resistance to freeze Cabbage............ 19-23 26-28 16-21 Soybeans .......... 25-27 26-28 26-28 Low resistance to freeze Corn .............. 26-28 28-30 26-28 Millet .............. 26-28 28-30 26-28 Sudangrass..........26-28 28-30 26-28 Sorghum............ 26-28 28-30 26-28 Potatoes.......26-28 28-30 28-30 No resistance to freeze Buckwheat.......... 28-30 28-30 28-31 Cotton ............. 28-30 28-30 26-28 Melons............. 30-31 30-31 30 Rice ............... 30-31 30-31 30-31 Peanuts ............ 30-31--- Cucumbers .......... 30-31--- Tomatoes........... 30-32 30-32 30-32 Tobacco............ 30-32 30-32 30-32 SOU% % %RE0%OF DATO A Stations used in the analysis were selected based on their length and quality of record, station exposure, and geogra- phical location. For analysis purposes, geographical loca- tion was important to ensure an adequate distribution of data points and as much uniformity as possible in the repre- sentative exposure of meteorological sites. The latitude, longitude, and elevation for these stationsare listed in table 4. The stations are numbered consecutively and grouped by climatological division. Temperature data for these stations are published monthly and annually in the Environmental Data and Information Service publication Climatological Data (Alabama Section). Table 4. Station Location and Elevation Station County Latitude Longitude Elevation Northern Valley 1. Athens. Limestone 2. Belle Mina Limestone 3. Falkville . Morgan 4. Florence .. Lauderdale 5. Madison .. Madison 6. Moulton . Lawrence 7. Muscle Shoals Colbert 8. Red Bay Franklin 9. Redstone Arsenal. . Madison 10. Russellville .. Franklin 11. Waterloo .. Lauderdale Appalachian Mountain 12. Albertville . Marshall 13. Bessemer.. Jefferson 14. Birmingham.Jefferson 15. Bridgeport. Jackson 16.Crossville DeKalb 17. Guntersville Marshall 18. Oneonta .. Blount 19. Saint Bernard. Cullman 20. Scottsboro. Jackson 21. Valley Head. DeKalb Upper Plains 22. Bankhead L&D Tuscaloosa 23. Centreville.. Bibb 24. Clanton... Chilton 25. Double Springs.. Winston 26. Fayette... Fayette 27. Haleyville .Wilnston 28. Hamilton . Marion 29. Prattville .. Autauga 30. Tuscaloosa .Tuscaloosa 31. Vernon Lamar Eastern Valley 32. Anniston .. Calhoun 33. Calera........ Shelby 34. Centre ... Cherokee 35. childersburg Talladega 36. Gadsden . Etowah 37. Sylacauga.. Talladega 38. Talladega.. Talladega Piedmont Plateau 39. Auburn ... Lee 40. Ashland .. Clay 41. Camp Hill.. Tallapoosa 42. Heflin....... Cleburn 43. Lafayette .. Chambers 44. Martin Dam Elmore 45. Rockford.. Coosa 46. Rock Mills Randolph Prairie 47. Dayton... Marengo 48. Demopolis L&D ......... Marengo 49. Greensboro Hale 50. Livingston.. Sumter 51. Marion Junction ... Dallas 52. Minter Dallas 53. Montgomery . Montgomery 54. Selma ... Dallas 55. Union Springs Bullock Coastal Plain 56.0 Analsa . Cvngo 34048P 34042' 34022' 340450' 34042' 34029' 34045' 34026' 34035' 34031' 34055' 34014' 33 0 22' 33034' 34057' 34017' 34020' 33057' 34010' 34041' 34034' 33027' 32054' 32051' 34010' 33041' 34015' 34006' 32029' 33014' 33045' 33035' 33005' 34007' 33017' 34002' 33012' 33026" 320370 33015' 32050' 33039' 32054' 32040' 32054' 33009' 32022' 32031' 32042' 32035' 32028' 32006' 32018' 32025' 32006" 31019' 86059' 86053' 88053'* 87041' 88045' 8018' 8737' 88008, 86036' 87044' 88004' 86010Y 87001' 86045' 85043' 85058' 86019' 88029' 86049' 86003' 85037' 87021' 87015' 88038' 87024' 87049' 870370 57059' 86029' 87037' 88007' 85051' 88047' 85044' 86020' 88000' 86012' 86005' 85029' 85050' 85039' 85036' 85024' 85055' 88014' 85018' 87039' 87050' 87035' 88012' 87013' 87003' 88024' 87000' 55043' 88030' Feet 720 600 625 575 580 645 540 680 573 880 457 1,140 540 620 615 1,195 578 870 802 615 1,040 280 456 580 800 365 950 435 295 169 265 611 540 620 418 565 490 555 652 1,091 680 850 830 340 670 745 230 100 220 160 200 370 221 147 460 242 (Cont'd) 191 Table 4. (Cont'd) Station Location and Elevation Station County Latitude Longitude Elevation 57. Brewton .... Escambia 31004' 87003' 85 58. Brantley .... Crenshaw 31035' 86016' 274 59. Chatom ..... Washington 31032' 88015' 285 60. Clayton ..... Barbour 31053' 85028' 596 61. Frisco City... Monroe 31026' 87024' 410 62. Geneva ..... Geneva 31002' 85051' 110 63. Greenville... Butler 31049' 86038' 445 64. Headland ... Henry 31021' 85020' 370 65. Highland Home...... Crenshaw 31057' 86019' 594 66. Ozark ...... Dale 31031' 85041' 470 67. Thomasville.. Clark 31055' 87044' 405 68. Troy ....... Pike 31049' 85059' 580 Gulf 69. Bay Minette.. Baldwin 30053' 87047 268 70. Coden ..... Mobile 30023' 88014' 12 71. Fairhope.... Baldwin 30033' 87053' 23 72. Fort Morgan.. Baldwin 30014' 88001' 10 73. Mobile ..... Mobile 30041' 88015' 211 74. Robertsdale.. Baldwin 3034' 87044' 155 A climatological base map for Alabama is shown in figure 1 with outlines of the eight climatological divisions and the numbered weather stations for which freeze data is pres- ented in this publication, THE GROWING SEASON The true growing season may be defined as the period of the year during which temperatures remain high enough to permit a crop to grow. No clear standard for measuring an exact growing season has been established. Observed dates of last and first killing frost can be used; however, shelter temperatures that have reached freezing are more applica- ble to a wider area and more useful in describing the grow- ing season than subjective observations of frost damage to vegetation. Frost formation is often influenced by factors such as soil temperature, differences in elevation, and radi- ative exposure. Frost kill can also vary with the type of vegetation and its susceptibility to freeze damage. Often, this presents a problem in judging whether a frost has been severe enough to end a growing season or delay its beginning. On relatively calm, clear nights, temperatures at ground level are typically colder than at the standard 5 feet shelter height. Scattered frost damage may occur near the ground even though shelter temperatures are observed several degrees above freezing. Therefore, for a frost to be wide- spread enough to halt a growing season, temperatures at shelter height as well as at ground level are likely to have reached freezing. Table 5 contains data pertinent to growing season analy- sis. Included in this table are the years of freeze record used in this study, the mean and extreme dates of last spring and first fall freeze (32 0 F or lower), and the mean freeze-free period or growing season length for each station. The extreme occurrence dates are applicable only for the peri- ods of record used in this study. In figure 2, a map shows the statewide distribution of average length of growing season in days. The lines are of equal freeze-free period based on the average year. As we would expect, freezing temperatures occur both earlier in the fall and later in the spring over north Alabama. Across the Tennessee Valley the growing season runs an average of around 200 days. From there southward to the Gulf Coast, the transition from colder to warmer climate occurs with a 50- to 100-day geographic variation in length of growing [10] season. Between Huntsville and Mobile, for instance, the climatic difference in growing season averages about 70 days. Over interior areas, the growing season changes most rapidly along a 30- to 50-mile wide temperature belt that spans the midsection of the State and closely parallels the northern edge of the coastal plain. Possibly because of elevation differences along this zone, the growing season may differ by as much as 30 days over a distance of only 30 miles. Only in southwestern counties does the length of growing season change so rapidly toward the coast. The warmest climate within Alabama is found in the extreme southwestern counties. Near Mobile Bay and the Gulf Coast the yearly growing season averages almost 300 days, and the influence of a warm, marine environment becomes quite pronounced. FREEZE PROBABILITIES Freeze occurrences were tabulated from past years of record contained in the Environmental Data and Informa- tion Service publication Climatological Data (Alabama Sec- tion). Analysis was made to derive a climatic distribution for dates of first and last freeze. For the climatological stations used, the probabilities of a freeze occurring before certain dates in the fall and after certain dates in the spring were computed at temperature thresholds of 320, 280, 240, 200, and 16 0 F. Table 6 lists these dates by station and tempera- ture level for which selected freeze probabilities of 10%, 30%, 50%, 70%, and 90% applyforthe spring and fall season. Alabama's temperature climate is such that during all of the years examined, temperatures dropped to at least 28 0 F for stations selected over interior parts of the State. At temperatures below 28"F, however, the freeze records often contain a series of both freeze and freezeless years. This was especially true in southern portions of the State where, during unusually warm winters, coastal areas may miss a freeze entirely. Thom and Shaw (1958) have shown that freeze dates fol- low a normal frequency distribution and that statistical methods may be applied to determine probabilities for a freeze arriving before a certain date in the fall and after a certain date in the spring. The normal distribution of freeze dates is valid only when the particular temperature thre- shold is reached sometime during the season of each year. As mentioned above, this is not always the case for certain years in Alabama. A mixture of freeze and freezeless years occurs commonly with some of the colder temperature thresholds and the more southern stations within the State. The failure of a particular temperature threshold being reached during one or more of the years of record results in an incomplete series of freeze dates. Therefore, the condi- tional probability that for some years a freeze may not occur at all must also be considered. Thom's (1959) method for determining freeze probabilities from a series of both freeze and freezeless years was used in this study. For some stations with an incomplete series of freeze years, the probability of a particular temperature threshold being reached at all during the fall or spring season was less than the selected probability value. Therefore, a date cor- responding to that selected probability did not exist. In these cases, the date column in table 6 contains an asterisk. Dates corresponding to selected probabilities for the fall were sometimes calculated as occurring after January 1 of the following year. These were not ignored, but included in the freeze data to adequately describe the cold season climate. Therefore, the selected probability of a first fall freeze may occur after January 1. Similarly, when the calcu- lated data for the spring season was before January 1, the date was entered accordingly. A listing of statistical parameters used in the probability computations for each of the stations is given in Appendix I. The mean occurrence date is expressed as a day number beginning with January 1 as day number 1 and extending to values greater than 365 where some of the fall means occurred later in the cold season than December 31. The standard deviation and probability of temperature occur- rence during the year were also included for computing other risk factors if desired. FREEZE MAPS Accompanying the freeze probability tables are maps which provide a seasonal analysis of freeze risk for selected temperatures and probabilities. These maps give a geogra- phic description of the freeze climate within the State. Patterns and trends which show up on the maps may be further supplemented by the user's own knowledge of local meteorological factors. In figures 3 through 10, maps were analyzed forthe 50and 20 percent levels of freeze risk (1 year in 2and 1 year in 5) for 320 and 28*F temperatures. Lines were drawn to represent average dates of the particular freeze risk during the fall and spring seasons. For one's own area, intermediate dates between the lines may have to be interpolated. The map that is selected for any operational decision should depend on the amount of risk the user is willing to take. For example, figure 3 represents the average dates (50% chance) of first occurring 32 0 F freeze in the fall. Sim- ilarly, figure 5 is the analysis for the average dates of last occurring 32 0 F freeze in the spring. Based on past records, half of the time a 32 0 F freeze or colder (either first occurring in the fall or last occurring in the spring) will be experienced .earlier and half of the time later than the date indicated on the map. This 50 percent risk usually represents a greater chance than a farmer or other user is willing to take. It involves the operational threat that a 32*F freeze or lower would occur on the average of 1 out of every 2 years. For more precaution, the individual may decide that eco- nomically it is allowable for him to risk freeze damage during only 1 year out of 5. Figures 4 and 6 represent this 20 percent level of risk that an unseasonal freeze will affect his operations in the fall or spring. Similar risk levels were analyzed for the 28*F freeze thre- shold and presented in figures 7 through 10. For many industrial and farm interests, a 28*F temperature is more significant for scheduling operations and planning freeze alertness. Cold temperature extremes and their frequency of occur- rence can provide some definition to the severity of cold climate for a particular area. In figures 11, 12, and 13, the probability of a severe freeze occurrence during the cold season is analyzed for the freezing levels of 240, 200, and 160F. In these cases the probability lines represent the like- lihood of a given temperature level occurring at all during the cold season. Plans and decisions are often based on temperatures not falling below certain levels at anytime during the year. Such restrictions usually involve conditions of severe freeze. When building contractors lay pipe, for example, usually they must consider the freeze line, the depth of which depends largely upon the severity of winter- time temperatures. ln agriculture, the economic feasibility of certain farming practices may also depend upon how probable severe freeze conditions are for an area. CLIMATOLOGICAL PROBABILITIES AND FORECASTS Decisions about freeze protection are usually made from available weather forecasts and climatological information. Freeze probabilities based on climatology can be useful in planning operations a month or more in advance. However, for short range planning and where climatic vagaries are apparent, climatological probabilities of freeze should be supplemented or replaced by temperature forecasts for an immediate period of days or weeks. Probability dates are based on the climatology of past freeze occurrences whose dates were averaged over a period of years. When planning for the seasonal arrival of or end to freezing temperatures, the use of these dates implies that the temperature climate will continue to respond with about the same timing as in past years. This assumption may hold true only for most years. For example, a temporary trend toward shortened growing seasons within an abnor- mally cold cycle of years will often not be properly repres- ented by climatological statistics. Since climate is composed of many variations and an average is in reality only a statisti- cal tool, some emphasis should be placed with using shorter term forecasts that are available for the period in which decisions will apply. Temperature forecasts are intended to describe condi- tions representative of a general area as measured from an instrument shelter 5 feet above ground. Local environ- ments may require some adjustment to these forecasts. A particular farm's location may be consistently colder or warmer than a generalized area forecast would indicate. A field that is naturally colder than surrounding countryside might be prone to a more severe frost kill than would be indicated by the predicted minimum temperature. Like- wise, crops grown on high ground might suffer less freeze injury than would be expected due to their warm exposure. Similar considerations also need to be used when applying freeze probability analysis to one's particular location. REFERENCES Carter, H.S. 1973. Spring and Fall Freezing Temperatures in Georgia. Ga. Agr. Exp. Sta. Res. Report 162. Athens, Ga., 34 pp. Cry, G.W. 1968. Freeze Probabilities in Louisiana. La. Coop. Ext. Svc. Pub. 1531. Baton Rouge, La., 31 pp. Curry, B.R. 1971. Freezing Temperatures in Oklahoma. Okla. Coop. Ext. Svc., Stillwater, Okla., 23 pp. Eichmeier, A.H., et al. 1965. Michigan freeze bulletin. Mich. Ag. Exp. Sta. Res. Report 26. East Lansing, Mich., 40 pp. Geiger, R. 1965. The climate near the ground. Harvard Uni- versity Press, Cambridge, Mass., 611 pp. Kish, A.J. 1975. The Probabilities of Spring and Fall Freezing temperatures in South Carolina. S.C. Ag. Exp. Sta. Bull. 588. Clemson, S.C., 29 pp. Thom, H.C.S. and R.H. Shaw 1958. Climatological Analysis of Freeze Data for Iowa. Monthly Weather Review, 86. 251-252. Thom, H.C.S. 1959. The Distribution of Freeze-Data and Freeze-Free Period for Climatological Series with Freeze- less Years. Monthly Weather Review, 87. 136-144. U.S. Dept. of Comm. 1947-1976. Climatological Data (Ala- bama Section). NOAA, Environmental Data and lnf or- mation Svc., Asheville, N.C. U.S. Dept. of Comm. 1975-1976. Climatography of the Uni- ted States No. 20. NOAA, Environmental Data and Information Svc., Asheville, N.C. U.S. Dept. of Comm. 1959. Climatography of the United States No. 60-1. NOAA, Environmental Data and Infor- mation Svc., Asheville, N.C. Ventskevich, G.Z. 1961. Agrometeorology (translated from Russian). Israel Program for Scientific Translation, Jerusa- lem. 300 pp. [11f FIG. 1. Location of 74 temperature reporting stations and 8 climatic divisions. [12] _____ ~ 190 250 Worm FIG; 2. Average length of the growing season, (days). [13] 200. 210--. 220 250- 260 # Cold I rl) r) r\ I I ~5r I I V///Y///PWL~Z~//A I'""""""I TABLE 5. FREEZE DATA (32 0 F) Extreme dates Years of Mean date Last in spring First in fail Mean freeze Station record Spring Fall Earliest Latest Earliest Latest free period Days Northern Valley 1. Athens.................... 22 Apr. 8 Oct. 28 Mar. 22 May 4 Oct. 3 Dec. 1 202 2. Belle Mina.................. 25 Apr. 4 Oct. 30 Feb. 18 Apr. 19 Oct. 3 Nov. 16 -208 3. Falkville.................... 21 Apr. 8 Oct. 27 Mar. 22 Apr. 21 Oct. 3 Nov. 14 201 4. Florence................... 23 Apr. 6 Oct. 24 Mar. 16 May 3 Oct. 3 Nov. 9 200 5. Madison................... 29 Apr. 6 Oct. 30 Mar. 18 Apr. 21 Oct. 18 Nov. 14 206 6. Moulton................... 20 Apr. 7 Oct. 27 Mar. 22 Apr. 16 Oct. 3 Nov. 14 202 7. Muscle Shoals............... 26 Mar. 26 Nov. 2 Feb. 18 Apr. 16 Oct. 18 Nov. 27 220 8. Red Bay.................... 20 Apr. 3 Nov. 6 Mar. 17 Apr. 17 Oct. 21 Nov. 20 216 9. Redstone Arsenal............ 23 Apr. 6 Oct. 27 Mar. 18 May 16 Oct. 3 Nov. 14 203 10. Russellville................. 23 Apr. 14 Oct. 27 Mar. 24 May 13 Sept. 29 Nov. 18 195 11. Waterloo................... 20 Apr. 15 Oct. 21 Mar. 23 May 10 Sept 29 Nov. 14 188 Appalachian Mountain 12. Albertville.................. 25 Apr. 3 Oct. 31 Mar. 20 Apr. 22 Oct. 3 Nov. 27 210 13. Bessemer................... 23 Apr . 2 Nov. 2 Feb. 23 Apr. 18 Oct. 19 Nov. 17 213 14. Birmingham................ 25 Mar. 31 N ov. 4 Mar. 10 Apr. 21 Oct. 20 Nov. 27 217 15. Bridgeport.................. 22 Apr. 12 Oct. 24 Mar. 22 Apr. 29 Oct. 3 Nov. 14 194 16. Crossville................... 25 Apr. 6 Oct. 29 Mar. 22 Apr. 21 Oct. 3 Nov. 14 205 17. Guntersville................ 23 Apr. 1 Nov. 5 Mar. 9 Apr. 28 Oct. 25 Nov. 21 217 18. Oneonta................... 26 Apr. 9 Oct. 27 Mar. 18 May 2 Sept. 30 Nov. 12 200 19. Saint Bernard............... 25 Apr. 9 Oct. 29 Mar. 19 May 4 Oct. 3 Nov. 21 202 20. Scottsboro.................. 25 Apr. 9 Oct. 27 Mar. 19 May 4 Oct. 3 Nov. 17 200 21. Valley Head................. 26 Apr. 21 Oct. 21 Apr. 1 May 10 Sept. 30 Nov. 9 182 Upper Plains 22. Bankhead L&D.............. 20 Mar. 31 Nov. 5 Mar. 11 Apr. 16 Oct. 20 Nov. 29 218 23. Centreville................. 26 Apr. 4 Nov. 1 Mar. 18 Apr. 21 Oct. 16 Nov. 16 210 24. Clanton.................... 26 Mar. 31 Oct. 31 Feb. 12 Apr. 21 Oct. 14 Nov. 16 213 25. Double Springs............. 20 Apr. 8 Oct. 30 Mar. 18 Apr. 29 Oct. 9 Nov. 27 204 26. Fayette............25 Apr. 7 Oct. 27 Mar. 22 May 4 Oct. 3 Nov. 14 202 27. Haleyville.................. 26 Apr. 7 Oct. 30 Mar. 19 Apr. 21 Oct. 16 Nov. 21 205 28. Hamilton................... 18 Apr. 14 Oct. 22 Mar. 23 May 5 Sept. 29 Nov. 7 190 29. Prattville................... 25 Mar. 21 Nov. 6 Feb. 18 Apr. 12 Oct. 20 Nov. 29 229 30. Tuscaloosa.................. 26 Mar. 27 Nov. 2 Mar. 10 Apr. 21 Oct. 18 Nov. 21 219 31. Vernon.................... 21 Apr. 12 Oct. 24 Mar. 23 May 4 Oct. 3 Nov. 14 194 Eastern Valley 32. Anniston................... 25 Apr. 1 Nov. 2 Mar. 9 Apr. 21 Oct. 17 Nov. 17 214 33. Calera ...................... 22 Apr. 10 Oct. 28 Mar. 18 May 13 Oct. 7 Nov. 16 200 34. Centre..................... 21 Apr. 3 Oct. 28 Mar. 10 Apr. 16 Oct. 3 Nov. 15 207 35. Childersburg................ 20 Apr. 5 Oct. 29 Mar. 18 Apr. 17 Oct. 4 Nov. 16 206 36. Gadsden................... 24 Apr. 7 Oct. 30 Mar. 18 Apr. 21 Oct. 12 Nov. 17 205 37. Sylacauga...................22 Apr. 8 Oct. 29 Mar. 22 Apr. 21 Sept. 30 Nov. 24 203 38. Talladega................... 26 Apr. 8 Oct. 29 Mar. 18 May 4 Oct. 7 Nov. 11 203 Piedmont Plateau 39. Auburn.................... 26 Mar. 28 N ov. 5 Mar. 6 Apr. 21 Oct. 19 Dec. 1 221 40. Ashland.................... 20 Apr. 4 Nov. 4 Mar. 18 Apr. 16 Oct. 20 Nov. 29 213 41. Camp Hill.................. 25 Apr. 6 Oct. 27 Mar. 11 May 4 Sept. 30 N ov. 9 204 42. Hefin...............2 Apr. 180 t.21 a. 22- M kAy 1'7 Sept.%30 ,No.9 185 55. Union Springs............. 25 Mar. 19 Nov. 9 Feb. 18 Apr. 11 Oct. 16 Nov. 30 234 I (Cont'd) [141 TABLE 5. (Cont'd) FREEZE DATA (32 0 F) Extreme dates Years of Mean date Last in spring First in fall Mean freeze Station record Spring Fall Earliest Latest Earliest Latest free period Coastal Plain 56. Andalusia ................ 25 Mar. 21 Nov. 9 Feb. 18 Apr. 11 Oct. 25 Dec. 15 232 57. Brewton ................. 26 Mar. 30 Oct. 29 Mar. 10 Apr. 21 Sept. 30 Nov. 10 212 58. Brantley .................. 21 Mar. 30 Oct. 30 Mar. 1 Apr. 17 Sept. 30 Nov. 14 213 59. Chatom .................. 25 Mar. 30 Nov. 6 Feb. 28 Apr. 21 Oct. 17 Nov. 22 220 60. Clayton ................ 21 Mar. 14 Nov. 14 Feb. 9 Apr. 11 Oct.25 Dec. 1 244 61. Frisco City................ 25 Mar. 17 Nov. 11 Feb. 7 Apr. 11 Oct. 28 Dec. 15 238 62. Geneva .................. 26 Mar. 19 Nov. 7 Feb. 18 Apr. 7 Oct. 11 Dec. 7 232 63. Greenville ............... 26 Mar. 16 Nov. 14 Feb. 2 Apr. 11 Oct. 28 Dec. 26 242 64. Headland ................. 25 Mar. 18 Nov. 12 Dec. 26 Mar. 31 Oct. 28 Dec. 17 248 65. Highland Home ........... 25 Mar. 18 Nov. 11 Feb. 18 Apr. 11 Oct. 27 Dec. 15 237 66. Ozark .................... 24 Mar. 12 Nov. 13 Jan. 31 Mar. 29 Nov. 2 Dec. 15 245 67. Thomasville ............... 26 Mar. 24 Nov. 8 Feb. 18 Apr. 14 Oct. 18 Nov. 29 228 68. Troy ..................... 26 Mar. 18 Nov. 15 Feb. 19 Apr. 11 Oct. 26 Dec. 15 241 Gulf 69. Bay Minette ............. 26 Mar. 4 Nov. 20 Feb. 1 Mar. 29 Oct. 28 Jan. 5 260 70. Coden ................... 21 Mar. 5 Nov. 18 Jan.10 Mar. 27 Oct. 27 Dec. 6 257 71. Fairhope ................. 29 Feb. 27 Nov. 23 Jan. 19 Mar. 29 Nov. 2 Dec. 26 268 72. Fort Morgan* ..... .... 27 Jan. 31 Dec. 28 Dec. 16 Mar. 27 Nov. 24 Feb. 12 330 73. Mobile ................... 25 Feb. 28 Nov. 26 Jan.17 Mar. 27 Oct. 28 Jan. 5 270 74. Robertsdale .............. 29 Mar. 8 Nov. 19 Feb. 5 Mar. 31 Oct. 28 Jan. 6 255 *Temperatures did not reach freezing in all years. TABLE 6. PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percentprobability of Percent probability of Indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Northern Valley 1. Athens (22 years) 2. Belle Mina (25 years) 3. Falkville (21 years) 4. Florence (23 years) 5. Madison (29 years) 6. Moulton (20 years) 7. Muscle Shoals (26 years) 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 Mar. 26 Mar. 18 Feb. 21 Feb. 1 Jan. 12 Mar. 19 Feb. 23 Jan. 30 Jan. 19 Dec. 25 Mar. 29 Mar. 12 Feb. 5 Jan. 28 Jan. 12 Mar. 21 Mar. 11 Feb. 17 Jan. 28 Jan. 14 Mar. 26 Mar. 5 Feb. 7 Jan. 19 Jan. 2 Mar. 28 Mar. 11 Feb. 10 Feb. 3 Jan. 13 Mar. 10 Feb. 28 Jan. 21 Jan. 7 Dec. 19 Apr. 3 Mar. 24 Mar. 5 Feb. 14 Jan. 30 Mar. 29 Mar. 10 Feb. 17 Feb. 4 Jan. 17 Apr. 4 Mar. 21 Feb. 21 Feb. 10 Jan. 28 Mar. 30 Mar. 21 Mar. 3 Feb. 14 Jan. 30 Apr. 2 Mar. 16 Feb. 23 Feb. 6 Jan. 26 Apr. 3 Mar. 18 Feb. 23 Feb. 15 Jan. 28 Mar. 19 Mar. 10 Feb. 9 Jan. 28 Jan. 15 Apr. 8 Mar. 28 Mar. 14 Feb. 24 Feb. 11 Apr. 4 Mar. 20 Mar. 1 Feb. 15 Jan. 31 Apr. 8 Mar. 27 Mar. 4 Feb. 20 Feb. 8 Apr. 6 Mar. 28 Mar. 13 Feb. 25 Feb. 10 Apr. 6 Mar. 23 Mar. 7 Feb. 18 Feb. 7 Apr. 7 Mar. 23 Mar. 5 Feb. 23 Feb. 6 Mar. 26 Mar. 16 Feb. 22 Feb. 10 Jan. 28 Apr. 14 Apr. 1 Mar. 23 Mar. 6 Feb. 23 Apr. 10 Mar. 30 Mar.13 Feb. 26 Feb. 13 Apr. 12 Apr. 2 Mar. 15 Mar. 1 Feb. 19 Apr. 13 Apr. 4 Mar. 24 Mar. 8 Feb. 21 Apr. 11 Mar. 30 Mar. 18 Mar. 3 Feb. 19 Apr. 11 Mar. 28 Mar. 14 Mar. 3 Feb. 16 Apr. 1 Mar. 22 Mar. 7 Feb. 22 Feb. 9 Apr. 22 Apr. 8 Apr. 4 Mar. 20 Mar. 13 Apr. 20 Apr. 14 Mar. 31 Mar. 14 Mar. 5 Apr. 18 Apr. 11 Mar. 30 Mar. 14 Mar. 7 Apr. 23 Apr. 14 Apr. 7 Mar. 24 Mar. 9 Apr. 18 Apr. 9 Apr. 4 Mar. 20 Mar. 7 Apr. 17 Apr. 4 Mar. 27 Mar. 15 Mar. 3 Apr. 10 Apr. 1 Mar. 25 Mar. 12 Feb. 25 Oct. 13 Oct. 19 Nov. 1 Nov. 12 Nov. 26 Oct. 17 Oct. 24 Nov. 1 Nov. 14 Nov. 29 Oct. 12 Oct. 21 Nov. 4 Nov. 15 Nov. 28 Oct. 13 Oct. 21 Nov.' 1 Nov. 12 Nov. 17 Oct. 21 Oct. 25 Nov. 3 Nov. 9 Nov. 21 Oct. 12 Oct. 25 Nov. 2 Nov. 14 Nov. 24 Oct. 21 Oct. 24 Nov. 2 Nov. 10 Nov. 29 Oct. 22 Oct. 29 Nov. 9 Nov. 24 Dec. 8 Oct. 24 Oct. 31 Nov.10 Nov. 26 Dec. 13 Oct. 21 Oct. 30 Nov. 12 Nov. 27 Dec. 12 Oct. 19 Oct. 31 Nov. 10 Nov. 22 Dec. 4 Oct. 27 Nov. 1 Nov. 13 Nov. 22 Dec. 5 Oct. 21 Nov. 2 Nov. 10 Nov. 25 Dec. 7 Oct. 28 Nov. 1 Nov. 15 Nov. 26 Dec. 18 Oct. 28 Nov. 5 Nov. 14 Dec. 3 Dec. 16 Oct. 30 Nov. 5 Nov.16 Dec. 4 Dec. 24 Oct. 27 Nov. 6 Nov. 18 Dec. 5 Dec. 21 Oct. 24 Nov. 7 Nov. 16 Nov. 30 Dec. 16 Oct. 30 Nov. 5 Nov. 19 Dec. 1 Dec. 15 Oct. 27 Nov. 7 Nov. 16 Dec. 3 Dec. 16 Nov. 2 Nov. 7 Nov. 23 Dec. 7 Jan. 1 Nov. 3 Nov. 12 Nov 19 Dec. 11 Dec. 25 Nov. 4 Nov. 10 Nov. 22 Dec. 13 Jan. 3 Nov. 2 Nov. 12 Nov. 23 Dec. 13 Dec. 30 Oct. 29 Nov. 14 Nov. 22 Dec. 7 Dec. 28 Nov. 3 Nov. 10 Nov. 25 Dec. 9 Dec. 25 Nov. 2 Nov. 12 Nov. 21 Dec. 11 Dec. 25 Nov. 6 Nov. 13 Dec. 2 Dec. 19 Jan. 17 Nov. 11 Nov. 22 Nov. 27 Dec. 24 Jan. 6 Nov. 12 Nov. 17 Dec. 1 Dec. 25 Jan. 20 Nov. 10 Nov. 21 Dec. 2 Dec. 24 Jan. 13 Nov. 5 Nov. 23 Dec. 1 Dec. 18 Jan. 14 Nov. 9 Nov. 17 Dec. 5 Dec. 22 Jan. 14 Nov. 11 Nov. 19 Nov. 30 Dec. 22 Jan. 7 Nov. 13 Nov. 22 Dec. 15 Jan. 7 (Cont'd) (Cont'd) [151 TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% . . .. . tim . -. . i Northern Valley (Conta) 8. Red Bay (20 years) 9. Redstone Arsenal (23 years) 10. Russellville (23 years) 11. Waterloo (20 years) Applachian Mountain 12. Albertville (25 years) 13. Bessemer (23 years) 14. Birmingham (25 years) 15. Bridgeport (22 years) 16. Crossville (25 years) 17. Guntersville (23 years) 18. Oneonta (26 years) 19. Saint Bernard (25 years) 20. Scottsboro (25 years) 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 Mar. 22 Mar. 5 Feb. 13 Feb. 2 Jan. 14 Mar. 21 Feb. 28 Feb. 12 Jan. 25 Jan. 4 Mar. 30 Mar. 18 Mar. 8 Feb. 4 Jan. 24 Mar. 31 Mar. 23 Feb. 23 Jan. 27 Jan. 19 Mar. 22 Mar. 5 Feb. 4 Jan. 20 Dec. 27 Mar. 17 Mar. 2 Feb. 13 Jan. 17 Dec. 21 Mar. 17 Feb. 16 Jan. 28 Dec. 29 * Mar. 31 Mar. 21 Feb. 25 Feb. 3 Jan. 20 Mar. 26 Mar. 11 Feb. 6 Jan. 20 Jan. 1 Mar. 18 Feb. 21 Feb. 4 Jan. 20 Jan. 1 Mar. 27 Mar. 16 Feb. 18 Jan. 15 * Mar. 27 Mar. 15 Feb. 23 Jan. 27 Jan. 5 Mar. 27 Mar. 12 Feb. 24 Jan. 31 Jan. 9 Mar. 29 Mar. 13 Feb. 25 Feb. 14 Jan. 28 Mar. 30 Mar. 13 Feb. 26 Feb. 8 Jan. 24 Apr. 9 Mar. 26 Mar. 15 Feb. 20 Feb. 9 Apr. 9 Mar. 30 Mar. 9 Feb. 13 Feb. 4 Mar. 29 Mar. 14 Feb. 20 Feb. 6 Jan. 19 Mar. 27 Mar. 12 Feb. 25 Feb. 4 Jan. 14 Mar. 25 Mar. 2 Feb. 13 Jan. 22 Jan. 3 Apr. 7 Mar. 28 Mar. 8 Feb. 18 Feb. 4 Apr. 1 Mar. 20 Feb. 20 Feb. 7 Jan. 24 Mar. 26 Mar. 7 Feb. 19 Feb. 4 Jan. 19 Apr. 4 Mar. 24 Mar. 1 Feb. 3 Jan. 10 -Apr. 4 Mar. 23 Mar. 6 Feb. 12 Jan. 27 Apr. 4 Mar. 21 Mar. 6 Feb. 14 Jan. 28 Apr. 3 Mar. 18 Mar. 5 Feb. 22 Feb. 7 Apr. 6 Mar. 21 Mar. 8 Feb. 18 Feb. 5 Apr. 16 Mar. 31 Mar. 20 Mar. 3 Feb. 20 Apr. 15 Apr. 4 Mar. 18 Feb. 25 Feb. 16 Apr. 3 Mar. 20 Mar. 3 Feb. 18 Feb. 1 Apr. 2 Mar. 18 Mar. 6 Feb. 17 Jan. 29 Mar. 31 Mar. 13 Feb. 24 Feb. 5 Jan. 22 Apr. 12 Apr. 2 Mar. 16 Feb. 28 Feb. 14 Apr. 6 Mar. 26 Mar. 2 Feb. 20 Feb. 7 Apr. 1 Mar. 17 Mar. 2 Feb. 14 Feb. 1 Apr. 9 Mar. 29 Mar. 9 Feb. 16 Jan. 29 Apr. 9 Mar. 29 Mar. 13 Feb. 24 Feb. 9 Apr. 9 Mar. 27 Mar. 14 Feb. 24 Feb. 8 Apr. 7 Mar. 24 Mar. 14 Mar. 2 Feb. 17 Apr. 13 Mar. 30 Mar. 18 Feb. 28 Feb. 17 Apr. 23 Apr. 5 Mar. 25 Mar. 13 Mar. 3 Apr. 22 Apr. 9 Mar. 27 Mar. 8 Feb. 28 Apr. 8 Mar. 26 Mar. 14 Mar. 2 Feb. 15 Apr. 9 Mar. 25 Mar. 14 Mar. 1 Feb. 12 Apr. 6 Mar. 23 Mar. 6 Feb. 19 Feb. 5 Apr. 17 Apr. 7 Mar. 24 Mar. 10 Feb. 25 Apr. 10 Mar. 31 Mar. 13 Mar. 4 Feb. 21 Apr. 7 Mar. 27 Mar. 12 Feb. 25 Feb. 14 Apr. 15 Apr. 4 Mar. 17 Mar. 1 Feb. 14 Apr. 14 Apr. 4 Mar. 21 Mar. 7 Feb. 22 Apr. 15 Apr. 3 Mar. 21 Mar. 5 Feb. 19 Apr. 14 Mar. 31 Mar. 25 Mar. 14 Mar. 3 Apr. 22 Apr. 11 Apr. 1 Mar. 15 Mar. 5 May 2 Apr. 13 Apr. 1 Mar. 29 Mar. 18 May 1 Apr. 16 Apr. 10 Mar. 25 Mar. 16 Apr. 15 Apr. 5 Mar. 30 Mar. 19 Mar. 6 Apr. 18 Apr. 4 Mar. 26 Mar. 19 Mar. 5 Apr. 15 Apr. 6 Mar. 22 Mar. 11 Feb. 24 Apr. 24 Apr. 14 Apr. 4 Mar. 25 Mar. 12 Apr. 16 Apr. 9 Mar. 27 Mar. 23 Mar. 13 Apr. 16 Apr. 10 Mar. 28 Mar. 12 Mar. 5 Apr. 23 Apr. 12 Mar. 28 Mar. 20 Mar. 9 Apr. 22 Apr. 12 Apr. 1 Mar. 24 Mar. 12 Apr. 22 . Apr. 12 Apr. 1 Mar. 20 Mar. 7 Oct. 26 Nov. 3 Nov. 6 Nov. 21 Nov. 27 Oct. 14 Oct. 24 Oct. 30 Nov. 13 Nov. 18 Oct. 10 Oct. 21 Oct. 27 Oct. 31 Nov. 10 Oct. 6 Oct. 13 Oct. 29 Nov. 3 Nov. 19 Oct. 17 Oct. 27 Nov. 1 Nov. 15 Nov. 26 Oct. 22 Oct. 24 Oct. 31 Nov. 15 Nov. 30 Oct. 24 Oct. 28 Nov. 8 Nov. 26 Dec. 5 Oct. 10 Oct. 22 Oct. 30 Nov. 9 Nov. 19 Oct. 16 Oct. 20 Oct. 29 Nov. 13 Nov. 19 Oct. 25 Oct. 28 Nov. 8 Nov. 22 Nov. 29 Oct. 13 Oct. 23 Oct. 26 Nov. 6 Nov. 23 Oct. 17 Oct. 25 Oct. 30 Nov. 10 Nov. 19 Oct. 12 Oct. 23 Oct. 28 Nov. 4 Nov. 15 Nov. 2 Nov. 9 Nov. 18 Dec. 1 Dec. 13 Oct. 22 Oct. 31 Nov. 8 Nov. 24 Nov. 30 Oct. 19 Oct. 28 Nov. 4 Nov. 13 Nov. 23 Oct. 15 Oct. 23 Nov. 7 Nov. 17 Dec. 1 Oct. 25 Nov. 4 Nov. 14 Nov. 27 Dec. 13 Oct. 28 Oct. 31 Nov. 13 Nov. 30 Dec. 18 Oct. 31 Nov. 6 Nov. 20 Dec. 9 Dec. 23 Oct. 18 Oct. 28 Nov. 8 Nov. 17 Dec. 2 Oct. 24 Oct. 30 Nov. 6 Nov. 25 Dec. 4 Oct. 31 Nov. 7 Nov. 19 Dec. 1 Dec. 17 Oct. 21 Oct. 30 Nov. 7 Nov. 23 Dec. 11 Oct. 24 Nov. 1 Nov. 10 Nov. 23 Dec. 4 Oct. 21 Oct. 30 Nov. 6 Nov. 17 Dec. 1 Nov. 6 Nov. 14 Nov. 25 Dec. 8 Dec. 24 Oct. 27 Nov. 4 Nov. 14 Dec. 3 Dec. 8 Oct. 26 Nov. 1 Nov. 9 Nov. 22 Dec. 2 Oct. 21 Oct. 30 Nov. 14 Nov. 28 Dec. 10 Oct. 31 Nov. 10 Nov. 23 Dec. 6 Dec. 25 Nov. 2 Nov. 5 Nov. 22 Dec. 10 Jan. 1 Nov. 4 Nov. 12 Nov. 28 Dec. 19 Jan. 5 Oct. 24 Nov. 1 Nov. 14 Nov. 23 Dec. 11 Oct. 29 Nov. 5 Nov. 12 Dec. 4 Dec. 15 Nov. 5 Nov. 13 Nov. 26 Dec. 8 Dec. 30 Oct. 27 Nov. 4 Nov. 16 Dec. 5 Dec. 23 Oct. 29 Nov. 6 Nov. 17 Dec. 1 Dec. 14 Oct. 27 Nov. 3 Nov. 12 Nov. 25 Dec. 12 Nov. 10 Nov. 16 Nov.-18 Nov. 25 Dec. 3 Dec. 14 Dec. 15 Dec. 25 Jan. 4 Jan. 19 Nov. 1 Nov. 9 Nov. 8 Nov. 15 Nov. 20 Nov. 29 Dec. 11 Dec. 22 Dec. 17 Dec. 29 Nov. 1 Nov. 11 Nov. 6 Nov. 12 Nov. 15 Nov. 23 Nov. 30 Dec. 13 Dec. 12 Dec. 25 Oct. 27 Nov. 5 Nov. 7 Nov. 17 Nov. 20 Nov. 29 Dec. 8 Dec. 22 Dec. 19 Jan. 1 Nov. 6 Nov. 15 Nov. 15 Nov. 24 Dec. 2 Dec. 14 Dec. 15 Dec. 28 Jan. 7 Jan. 27 Nov. 6 Nov. 12 Nov. 10 Nov. 18 Nov. 30 Dec. 13 Dec. 19 Jan. 3 Jan. 14 Feb. 6 Nov. 8 Nov. 15 Nov. 18 Nov. 26 Dec. 6 Dec. 17 Dec. 29 Jan. 15 Jan. 23 * Oct. 30 Nov. 6 Nov. 20 Nov. 29 Dec. 20 Nov. 3 Nov. 11 Nov. 17 Dec. 13 Dec. 25 Nov. 9 Nov. 19 Dec. 4 Dec. 14 Jan. 12 Nov. 1 Nov. 10 Nov. 24 Dec. 16 Jan. 6 Nov. 3 Nov. 12 Nov. 24 Dec. 10 Dec. 25 Nov. 2 Nov. 8 Nov. 19 Dec. 4 Dec. 24 Nov. 8 Nov. 12 Nov. 29 Dec. 7 Jan. 2 Nov. 10 Nov. 20 Nov. 26 Dec. 26 Jan. 12, Nov. Nov. 29 Dec. 14 Dec. 24 Jan. 30 Nov. 9 Nov. 17 Dec. 6 Jan. 3 Nov. 10 Nov. 19 Dec. 4 Dec. 22 Jan. 12 Nov. 11 Nov. 14 Nov. 28 Dec. 16 Jan. 11 (Cont'd) [16] TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Appalachian Mtn. (Con't) 21. Valley Head 320 (26 years) 280 240 200 160 Upper Plains 22. Bankhead L&D (20 years) 23. Centreville (26 years) 24. Clanton (26 years) 25. Double Springs (20 years) 26. Fayette (25 years) 27. Haleyville (26 years) 28. Hamilton (18 years) 29. Prattville (25 years) 30. Tuscaloosa (26 years) 31. Vernon (21 years) Eastern Valley 32. Anniston (25 years) 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 (Cont'd) [17J Apr. 7 Mar. 28 Mar. 8 Feb. 12 Jan. 14 Mar. 18 Feb. 22 Feb. 13 Jan. 13 * Mar. 23 Feb. 28 Jan. 22 Jan. 3 * Mar. 18 Feb. 20 Feb. 8 Jan. 1 Dec. 22 Mar. 27 Mar. 18 Feb. 24 Feb. 1 Jan. 22 Mar. 25 Feb. 28 Feb. 12 Jan. 17 Dec. 8 Mar. 26 Mar. 7 Feb. 15 Jan. 22 * Apr. 2 Mar. 16 Feb. 20 Feb. 7 Feb. 4 Mar. 7 Feb. 9 Jan. 16 Dec. 28 * Mar. 13 Feb. 20 Jan. 20 Dec. 22 * Mar. 28 Mar. 12 Feb. 12 Jan. 27 Jan. 17 Mar. 18 Mar. 1 Jan. 31 Jan. 8 * Apr. 15 Apr. 4 Mar. 19 Feb. 25 Feb. 2 Mar. 26 Mar. 5 Feb. 24 Feb. 1 Jan. 19 Mar. 30 Mar. 9 Feb. 10 Jan. 30 jan. 14 Mar. 25 Mar. 4 Feb. 20 Jan. 21 Jan. 10 Apr. 3 Mar. 26 Mar. 7 Feb. 16 Feb. 6 Apr. 2 Mar. 11 Feb. 24 Feb. 4 Jan. 11 Apr. 2 Mar. 16 Feb. 27 Feb. 9 Jan. 21 Apr. 9 Mar. 25 Mar. 7 Feb. 21 Feb. 17 Mar. 16 Feb. 24 Feb. 3 Jan. 16 Mar. 21 Mar. 4 Feb. 5 Jan. 15 Dec. 22 Apr. 6 Mar. 21 Feb. 26 Feb. 12 Feb. 3 Mar. 26 Mar. 11 Feb. 16 Jan. 28 Jan. 9 Apr. 21 Apr. 9 Mar. 27 Mar. 7 Feb. 15 Mar. 31 Mar. 14 Mar. 3 Feb. 14 Feb. 1 Apr. 4 Mar. 16 Feb. 23 Feb. 12 Jan. 30 Mar. 31 Mar. 13 Feb. 28 Feb. 5 Jan. 22 Apr. 8 Apr. 1 Mar. 14 Feb. 26 Feb. 16 Apr. 7 Mar. 19 Mar. 4 Feb. 16 Jan. 26 Apr. 7 Mar. 22 Mar. 7 Feb. 21 Feb. 5 Apr. 14 Mar. 31 Mar. 17 Mar. 3 Feb. 25 Mar. 21 Mar. 7 Feb. 16 Jan. 29 Jan. 13 Mar. 27 Mar. 12 Feb. 17 Jan. 30 Jan. 15 Apr. 12 Mar. 27 Mar. 8 Feb. 23 Feb. 15 Apr. 1 Mar. 19 Feb. 27 Feb. 9 Jan. 23 Apr. 26 Apr. 14 Apr. 4 Mar. 16 Mar. 1 Apr. 6 Mar. 22 Mar. 10 Feb. 27 Feb. 12 Apr. 10 Mar. 22 Mar. 8 Feb. 23 Feb. 13 Apr. 5 Mar. 22 Mar. 9 Feb. 19 Feb. 3 Apr. 13 Apr. 6 Mar. 22 Mar. 8 Feb. 27 Apr. 13 Mar. 27 Mar. 12 Feb. 28 Feb. 10 Apr. 12 Mar. 29 Mar. 16 Mar. 5 Feb. 19 Apr. 19 Apr. 6 Mar. 27 Mar. 13 Mar. 6 Mar. 27 Mar. 17 Mar. 1 Feb. 10 Jan. 30 Apr. 2 Mar. 20 Feb. 28 Feb. 14 Jan. 29 Apr. 18 Apr. 3 Mar. 18 Mar. 6 Feb. 26 Apr. 7 Mar. 26 Mar. 9 Feb. 21 Feb. 5 May 5 Apr. 21 Apr. 15 Mar. 30 Mar. 20 Apr. 13 Apr. 2 Mar. 21 Mar. 17 Feb. 28 Apr. 17 Mar. 31 Mar. 26 Mar. 12 Mar. 5 Apr. 12 Apr. 4 Mar. 21 Mar. 12 Feb. 20 Apr. 20 Apr. 14 Apr. 2 Mar. 23 Mar. 14 Apr. 21 Apr. 7 Mar. 24 Mar. 18 Mar. 2 Apr. 19 Apr. 7 Mar. 28 Mar. 23 Mar. 10 Apr. 26 Apr. 15 Apr. 10 Mar. 26 Mar. 18 Apr. 4 Apr. 2 Mar. 19 Feb. 27 Feb. 14 Apr. 11 Mar. 31 Mar. 16 Mar. 6 Feb. 15 Apr. 27 Apr. 12 Apr. 1 Mar. 21 Mar. 15 Apr. 15 Apr. 6 Mar. 25 Mar. 10 Feb. 22 Oct. 8 Oct. 19 Oct. 24 Oct. 31 Nov. 8 Oct. 23 Oct. 30 Nov. 13 Nov. 25 Dec. 6 Oct. 21 Oct. 23 Nov. 4 Nov. 16 Nov. 21 Oct. 20 Oct. 26 Oct. 31 Nov. 19 Dec. 1 Oct. 16 Oct. 25 Nov. 1 Nov. 11 Nov. 23 Oct. 15 Oct. 23 Nov. 1 Nov. 11 Nov. 23 Oct. 18 Oct. 26 Nov. 4 Nov. 8 Nov. 23 Oct. 7 Oct. 23 Oct. 26 Nov. 4 Nov. 17 Oct. 24 Nov. 2 Nov. 11 Nov. 23 Dec. 13 Oct. 22 Oct. 24 Nov. 8 Nov. 21 Dec. 7 Oct. 11 Oct. 22 Oct. 28 Nov. 7 Nov. 22 Oct. 22 Oct. 26 Nov. 2 Nov. 16 Dec. 3 Oct. 16 Oct. 26 Oct. 31 Nov. 11 Nov. 25 Oct. 31 Nov. 9 Nov. 25 Dec.- 8 Dec. 22 Oct. 27 Nov. 3 Nov. 17 Nov. 29 Dec. 11 Oct. 27 Nov. 3 Nov. 14 Nov. 30 Dec. 20 Oct. 24 Nov. 2 Nov. 11 Nov. 23 Dec. 6 Oct. 22 Nov. 1 Nov. 10 Nov. 24 Dec. 9 Oct. 25 Nov. 3 Nov. 14 Nov. 24 Dec. 6 Oct. 16 Oct. 30 Nov. 5 Nov. 13 Dec. 2 Nov. 1 Nov. 12 Nov. 22 Dec. 9 Jan. 5 Oct. 28 Nov. 4 Nov. 21 Dec. 6 Dec. 25 Oct. 19 Oct. 29 Nov. 6 Nov. 19 Dec. 4 Oct. 28 Nov. 3 Nov. 14 Nov. 29 Dec. 21 Oct. 21 Oct. 30 Nov. 5 Nov. 19 Dec. 6 Nov. 5 Nov. 16 Dec. 3 Dec. 17 Jan. 2 Nov. 1 Nov. 10 Nov. 25 Dec. 8 Dec. 26 Oct. 31 Nov. 8 Nov. 23 Dec. 8 Jan. 2 Oct. 30 Nov. 7 Nov. 18 Dec. 1 Dec. 15 Oct. 27 Nov. 6 Nov. 16 Dec. 4 Dec. 21 Oct. 30 Nov. 9 Nov. 22 Dec. 4 Dec. 16 Oct. 22 Nov. 4 Nov. 11 Nov. 19 Dec. 12 Nov. 6 Nov. 19 Dec. 1 Dec. 20 Jan. 30 Nov. 2 Nov. 11 Nov. 30 Dec. 16 Jan. 10 Oct. 24 Nov. 2 Nov. 12 Nov. 27 Dec. 12 Nov. 2 Nov. 9 Nov. 23 Dec. 8 Jan. 2 Oct. 26 Nov. 3 Nov. 10 Nov. 26 Dec. 18 Nov. 10 Nov. 23 Dec. 11 Dec. 26 Jan. 13 Nov. 5 Nov. 17 Dec. 4 Dec. 18 Jan. 13 Nov. 5 Nov. 13 Dec. 3 Dec. 15 Jan. 16 Nov. 5 Nov. 12 Nov. 25 Dec. 8 Dec. 24 Nov. 1 Nov. 12 Nov. 22 Dec. 13 Jan. 2 Nov. 4 Nov. 15 Nov. 29 Dec. 15 Dec. 27 Oct. 28 Nov. 9 Nov. 17 Nov. 25 Dec. 22 Nov. 11 Nov. 26 Dec. 9 Jan. 1 * Nov. 6 Nov. 19 Dec. 10 Dec. 27 Oct. 30 Nov. 7 Nov. 18 Dec. 5 Dec. 20 Nov. 6 Nov. 15 Dec. 2 Dec. 18 Jan. 17 Nov. 3 Nov. 10 Nov. 18 Dec. 7 Jan. 3 Nov. 17 Dec. 3 Dec. 23 Jan. 9 Feb. 3 Nov. 11 Nov. 27 Dec. 17 Jan. 8 * Nov. 11 Nov. 21 Dec. 16 Dec. 27 Feb. 8 Nov. 14 Nov. 19 Dec. 4 Dec. 20 Jan. 5 Nov. 9 Nov. 21 Nov. 30 Dec. 27 Jan. 29 Nov. 11 Nov. 24 Dec. 9 Dec. 30 * Nov. 6 Nov. 16 Nov. 27 Dec. 4 Jan. 6 Nov. 18 Dec. 5 Dec. 21 Jan. 19 * Nov. 12 Nov. 29 Dec. 23 Jan. 13 * Nov. 6 Nov. 13 Nov. 27 Dec. 17 Jan. 1 Nov. 12 Nov. 23 Dec. 14 Jan. 3 * TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Eastern Valley (Cont'd) 33. Calera (22 years) 34. Centre (21 years) 35. Childersburg (20 years) 36. Gadsden (24 years) 37. Sylacauga (22 years) 38. Talladega (26 years) Piedmont Plateau 39. Auburn (26 years) 40. Ashland (20 years) 41. Camp Hill (25 years) 42. Heflin (21 years) 43. Lafayette (29 years) 44. Martin Dam (26 years) 45. Rockford (23 years) 320 280 240 200 160 320 288 240 20* 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 Mar. 23 Mar. 12 Feb. 17 Jan. 28 Jan. 2 Mar. 21 Mar. 9 Feb. 6 Jan. 24 Jan. 1 Mar. 24 Feb. 27 Feb. 14 Jan. 28 Jan.13 Mar. 24 Mar. 4 Feb. 13 Jan. 12 Dec. 21 Mar. 28 Mar. 3 Feb. 16 Jan.:26 Jan. 15 Mar. 24 Mar. 13 Feb. 11 Jan. 12 * Mar. 14 Feb. 12 Jan. 26 Jan. 6 S Mar. 23 Mar. 3 Feb. 10 Jan. 31 Jan. 13 Mar. 21 Feb. 23 Feb. 3 Jan. 15 Dec. 31 Mar. 31 Mar. 21 Feb. 26 Feb. 11 Jan. 24 Mar. 14 Feb. 18 Jan. 19 Jan. 5 * Mar. 8 Feb. 10 Jan. 16 * * Mar. 23 Mar. 9 Feb. 17 Jan. 21 Jan. 8 Apr. 3. Mar. 21 Mar. 2 Feb. 12 Jan. 22 Mar. 29 Mar. 18 Feb. 21 Feb. 5 Jan. 21 Mar. 31 Mar. 12 Feb. 26 Feb. 9 Jan. 29 Apr. 1 Mar. 14 Feb. 26 Jan. 30 Jan. 18 Apr. 4 Mar. 13 Feb. 27 Feb. 10 Jan. 30 Apr. 2 Mar. 21 Feb. 26 Jan. 30 Jan. 15 Mar. 22 Feb. 28 Feb. 10 Jan. 25 Dec. 30 Mar. 30 Mar. 15 Feb. 24 Feb. 12 Jan. 27 Mar. 31 Mar. 10 Feb. 19 Feb. 2 Jan. 22 Apr. 10 Mar. 30 Mar. 10 Feb. 23 Feb. 7 Mar. 23 Mar. 3 Feb. 7 Jan. 28 Jan. 6 Mar. 19 Feb. 23 Feb. 2 Jan. 6 * Mar. 31 Mar. 17 Feb. 28 Feb. 7 Jan. 26 Apr. 10 Mar. 27 Mar. 10 Feb. 22 Feb. 4 Apr. 3 Mar. 25 Mar. 4 Feb. 14 Feb. 3 Apr. 5 Mar. 20 Mar. 6 Feb. 18 Feb. 9 Apr. 7 Mar. 21 Mar: 7 Feb. 11 Jan. 30 Apr. 8 Mar. 20 Mar. 7 Feb. 20 Feb. 9 Apr. 8 Mar. 27 Mar. 8 Feb. 11 Feb. 2 Mar. 28 Mar. 10 Feb. 21 Feb. 8 Jan. 19 Apr. 4 Mar. 22 Mar. 6 Feb. 20 Feb. 6 Apr. 6 Mar. 20 Mar. 2 Feb. 14 Feb. 5 Apr. 18 Apr. 5 Mar. 19 Mar. 4 Feb. 17 Mar. 29 Mar. 12 Feb. 20 Feb. 11 Jan. 24 Mar. 26 Mar. 4 Feb. 15 Jan. 21 Jan. 9 Apr. 6 Mar. 23 Mar. 8 Feb. 19 Feb. 7 Apr. 17 Apr. 3 Mar. 18 Mar. 4 Feb. 18 Apr. 9 Mar. 31 Mar. 15 Feb. 23 Feb. 14 Apr. 10 Mar. 29 Mar. 14 Feb. 26 Feb. 19 Apr. 12 Mar. 28 Mar. 16 Feb. 24 Feb. 11 Apr. 12 Mar. 26 Mar. 15 Mar. 2 Feb. 20 Apr. 14 Apr. 2 Mar. 18 Feb. 23 Feb. 18 Apr. 3 Mar. 21 Mar. 4 Feb. 21 Feb. 1 Apr. 9 Mar. 30 Mar. 16 Mar. 1 Feb. 16 Apr. 12 Mar. 31 Mar. 14 Feb. 26 Feb. 18 Apr. 25 Apr. 12 Mar. 27 Mar. 13 Feb. 27 Apr. 5 Mar. 21 Mar. 5 Feb. 25 Feb. 8 Apr. 2 Mar. 13 Feb. 27 Feb. 4 Jan. 26 Apr. 11 Mar. 29 Mar. 16 Mar. 3 Feb. 19 Apr. 27 Apr. 12 Mar. 30 Mar. 19 Mar. 10 Apr. 17 Apr. 9 Mar. 31 Mar. 8 Mar. 3 Apr. 18 Apr. 10 Mar. 26 Mar. 10 Mar. 7 Apr. 20 Apr. 6 Mar. 29 Mar. 13 Feb. 26 Apr. 19 Apr. 5 Mar. 27 Mar. 16 Mar. 6 Apr. 23 Apr. 11 Apr. 2 Mar. 13 Mar. 12 Apr. 11 Apr. 6 Mar. 19 Mar. 12 Feb. 22 Apr. 16 Apr 10 Mar. 30 Mar. 13 Mar. 3 Apr. 22 Apr. 15 Mar. 30 Mar. 15 Mar. 8 May 6 Apr. 21 Apr. 9 Mar. 26 Mar. 13 Apr. 14 Apr. 2 Mar. 23 Mar. 17 Mar. 1 Apr. 12 Mar. 26 Mar. 17 Feb. 23 Feb. 12 Apr. 19 Apr. 6 Mar. 28 Mar. 21 Mar. 8 Oct. 15 Oct. 21 Oct. 29 Nov. 11 Nov. 22 Oct. 15 Oct. 26 Nov. 2 Nov. 12 Nov. 29 Oct. 14 Oct. 25 Nov. 2 Nov. 14 Nov. 28 Oct. 19 Oct. 25 Oct. 30 Nov. 14 Nov. 29 Oct. 13 Oct. 23 Nov. 3 Nov. 8 Nov. 27 Oct. 18 Oct. 21 Oct. 31 Nov. 16 Nov. 28 Oct. 23 Oct. 25 Nov. 8 Nov. 15 Nov. 29 Oct. 23 Oct. 28 Nov. 4 Nov. 20 Nov. 24 Oct. 15 Oct. 26 Nov. 1 Nov. 15 Nov. 25 Oct. 7 Oct. 22 Oct. 28 Nov. 2 Nov. 24 Oct. 23 Oct. 30 Nov. 14 Nov. 21 Nov. 28 Oct. 27 Nov. 3 Nov. 23 Dec. 4 Dec. 15 Oct. 16 Oct. 24 Nov. 1 Nov. 14 Nov. 21 Oct. 23 Oct. 30 Nov. 7 Nov. 23 Dec. 8 Oct. 23 Nov. 2 Nov. 11 Nov. 26 Dec. 14 Oct. 23 Nov. 1 Nov. 11 Nov. 26 Dec. 15 Oct. 26 Nov. 1 Nov. 9 Nov. 27 Dec. 21 Oct. 22 Nov. 2 Nov. 12 Nov. 21 Dec. 14 Oct. 24 Oct. 31 Nov. 11 Nov. 27 Dec. 18 Oct. 31 Nov. 7 Nov. 21 Dec. 2 Dec. 19 Oct. 30 Nov. 6 Nov. 15 Dec. 1 Dec. 8 Oct. 22 Nov. 2 Nov. 12 Nov. 27 Dec. 14 Oct. 15 Oct. 27 Nov. 4 Nov. 12 Dec. 3 Oct. 30 Nov. 5 Nov. 26 Dec. 3 Dec. 19 Nov. 6 Nov. 16 Dec. 7 Dec. 20 Jan. 4 Oct. 24 Nov. 1 Nov. 12 Nov. 27 Dec. 9 Oct. 28 Nov. 5 Nov. 14 Dec. 1 Dec, 20 Oct. 28 Nov. 7 Nov. 18 Dec. 5 Dec. 25 Oct. 29 Nov. 6 Nov. 17 Dec. 5 Dec. 26 Oct. 30 Nov. 6 Nov. 15 Dec. 6 Jan. 6 Oct. 29 Nov. 8 Nov. 18 Nov. 30 Dec. 25 Oct. 29 Nov. 7 Nov. 19 Dec. 5 Jan. 2 Nov. 5 Nov. 16 Nov. 30 Dec. 14 Jan. 3 Nov. 4 Nov. 12 Nov. 23 Dec. 8 Dec. 18 Oct. 27 Nov. 7 Nov. 19 Dec. 5 Dec. 27 Oct. 21 Oct. 31 Nov. 8 Nov. 19 Dec. -9 Nov. 5 Nov. 9 Dec. 5 Dec. 12 Jan. 4 Nov. 12 Nov. 25 Dec. 16 Jan. 1 Jan. 23 Oct. 30 Nov. 6 Nov. 20 Dec. 6 Dec. 23 Nov. 3 Nov. 11 Nov.21 Dec. 9 Dec. 31 Nov. 2 Nov. 12 Nov. 25 Dec. 15 Jan. 6 Nov. 4 Nov. 11 Nov. 23 Dec. 13 Jan. 7 Nov. 4 Nov. 10 Nov. 22 Dec. 15 Jan. 25 Nov. 5 Nov. 15 Nov. 25 Dec. 9 Jan. 6 Nov. 2 Nov. 14 Nov. 27 Dec. 13 Jan. 18 Nov. 11 Nov. 25 Dec. 10 Dec. 26 Jan. 24 Nov. 9 Nov. 19 Dec. 1 Dec. 16 Dec. 28 Nov. 2 Nov. 12 Nov. 27 Dec. 13 Jan. 10 Oct. 27 Nov. 4 Nov. 13 Nov. 27 Dec. 15 Nov. 10 Nov. 14 Dec. 13 Dec. 21 Jan. 22 Nov. 19 Dec. 4 Dec. 25 Jan. 14 Nov. 4 Nov. 12 Nov. 28 Dec. 15 Jan. 5 Nov. 10 Nov. 19 Dec. 1 Dec. 21 Jan. 17 Nov. 10 Nov. 19 Dec. 5 Dec. 28 Feb. 10 Nov. 12 Nov. 18 Dec. 2 Dec. 26 Jan. 23 Nov. 11 Nov. 17 Dec. 2 Dec. 27 * Nov. 14 Nov. 24 Dec. 4 Dec. 22 Jan. 23 Nov. 8 Nov. 24 Dec. 8 Dec. 25 Nov. 19 Dec. 7 Dec. 23 Jan. 12 * Nov. 17 Nov. 28 Dec. 13 Dec. 27 Jan. 11 Nov. 9 Nov. 19 Dec. 8 Dec. 25 Feb. 1 Nov. 4 Nov. 10 Nov. 20 Dec. 7 Dec. 25 Nov. 17 Nov. 20 Dec. 26 Jan. 5 * Nov. 29 Dec. 17 Jan. 8 * * Nov. 13 Nov. 20 Dec. 9 Dec. 27 Jan. 24 (Cont'd) [181 TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated terneatr indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Piedmont Plateau (Cont'd)I 46. Rock Mills 320 Mar. 27 Apr. 4 Apr. 10 Apr. 15 Apr. 24 Oct. 17 Oct. 24 Oct. 29 NOV. 2 Nov. 9 (26 years) 280 Mar. 9 Mar. 18 Mar. 24 Mar. 30 Apr. 9 Oct. 27 N ov. 2 Nov. 6 Nov. 10 Nov. 16 240 Feb. 13 Feb. 26 Mar. 7 Mar. 16 Mar. 29 Nov. 1 Nov. 11 Nov. 18 Nov. 24 Dec. 4 200 Jan. 5 Jan. 30 Feb. 15 Mar. 2 Mar. 23 Nov. 11 Nov. 23 Dec. 2 Dec. 11 Dec. 26 160 Dec. 18 Jan. 16 Jan. 30 Feb. 12 Mar. 3 Nov. 25 Dec. 14 Dec. 27 Jan. 11 Feb. 10 Prairie 47. Dayton 320 Mar. 5 Mar. 14 Mar. 20 Mar. 26 Apr 4 Oct. 26 Nov. 2 Nov. 6 Nov. 11 Nov. 17 (25 years) 280 Feb. 7 Feb. 21 Mar. 3 Mar. 13 Mar. 27 Nov. 3 Nov. 13 Nov. 19 Nov. 26 Dec. 6 240 Jan. 15 Feb. 2 Feb. 15 Feb. 28 Mar. 18 Nov. 10 Nov. 22 Dec. 1 Dec. 9 Dec. 21 200D Dec. 29 Jan. 19 Feb. 2 Feb. 17 Mar. 9 Nov. 25 Dec. 11 Dec. 23 Jan. 3 Jan. 19 160 Jan. 15 Jan. 29 Feb. 13 Dec. 19 Jan. 4 Jan. 19 * 48. Demopolis 320 Feb. 28 Mar. 11 Mar. 19 Mar. 26 Apr. 7 Oct. 24 Oct. 31 Nov. 6 Nov. 11 Nov. 19 L&D 280 Feb. 5 Feb. 20 Mar. 2 Mar. 11 Mar. 24 Oct. 27 Nov. 8 Nov. 17 Nov. 25 Dec. 8 (25 years) 240 Jan. 6 Jan. 29 Feb. 12 Feb. 26 Mar. 17 Nov. 5 Nov. 21 Dec. 2 Dec. 13 Dec. 30 200 Dec. 18 Jan. 10 Jan. 24 Feb. 6 Feb. 25 Nov. 17 Dec. 5 Dec. 18 Dec. 30 Jan. 17 160 * Jan. 4 Jan. 22 Feb. 9 Dec. 15 Dec. 31 Jan. 14 * 49. Greensboro 320 Mar. 6 Mar. 16 Mar. 22 Mar. 29 Apr. 8 Oct. 27 Nov. 3 Nov. 8 Nov. 13 Nov. 20 (25 years) 280 Feb. 13 Feb. 25 Mar. 5 Mar. 13 Mar. 25 Nov. 2 Nov. 15 Nov. 24 Dec. 3 Dec. 16 240 Jan. 21 Feb. 7 Feb. 19 Mar. 3 Mar. 20 Nov. 14 Nov. 26 Dec. 4 Dec. 12 Dec. 24 200 Dec. 29 Jan. 21 Feb. 5 Feb. 21 Mar. 16 Nov. 23 Dec. 9 Dec. 20 Dec. 31 Jan. 15 160 * Jan. 8 Jan. 24 Feb. 11 Dec. 8 Dec. 23 Jan. 5 * 50. Livingston 320 Mar. 8 Mar. 22 Mar. 28 Apr. 3 Apr. 11 Oct. 17 Oct. 26 Nov. 2 Nov. 9 Nov. 25 (23 years) 280 Feb. *2 Feb. 24 Mar. 6 Mar. 15 Mar. 28 Oct. 29 Nov. 7 Nov. 14 Nov. 21 Dec. 6 240 Jan. 13 Feb. 7 Feb. 18 Mar. 1 Mar. 15 Nov. 6 Nov. 19 Nov. 27 Dec. 7 Dec. 27 200 Dec. 12 Jan. 15 Jan. 31 Feb. 14 Mar. 6 Nov. 15 Nov. 28 Dec. 7 Dec. 17 Jan. 8 160 * Dec. 29 Jan. 14 Jan. 26 Feb. 10 Dec. 2 Dec. 18 'Dec. 31 Jan. 17 51. Marion junction 320 Mar. 6 Mar. 15 Mar. 22 Mar. 29 Apr. 8 Oct. 23 Oct. 30 Nov. 3 Nov. 8 Nov. 15 (27 years) 280 Feb. 16 Feb. 27 Mar. 7 Mar. 15 Mar. 27 Oct. 30 Nov. 7 Nov. 12 Nov. 17 Nov. 25 240 Jan. 25 Feb. 10 Feb. 20 Mar. 2 Mar. 15 Nov. 1 Nov. 15 Nov. 24 Dec. 4 Dec. 18 200 Dec. 24 Jan. 15 Jan. 29 Feb. 12 Mar. 3 Nov. 14 Nov. 28 Dec. 8 Dec. 18 Jan. 1 160 * Jan. 13 Jan. 28 Feb. 14 Dec. 2 Dec. 19 Jan. 3 Feb. 12 * 52. Minter 320 Feb. 25 Mar. 8 Mar. 16 Mar. 24 Apr. 4 Oct. 27 Nov. 5 Nov. 11 Nov. 16 Nov. 25 (20 years) 280 Feb. 12 Feb. 24 Mar. 5 Mar. 13 Mar. 25 Nov. 2 Nov. 12 Nov. 19, Nov. 25 Dec. 5 240 Feb. 2 Feb. 16 Feb. 25 Mar. 6 Mar. 20 Nov. 14 Nov. 26 Dec. 4 Dec. 12 Dec. 24 200 * Jan. 15 Jan. 29 Feb. 11 Feb. 28 Nov. 19 Dec. 7 Dec. 20 Jan. 4 160 * Jan. 3 Jan. 22 Feb. 4 Feb. 19 Dec. 11 Dec. 26 Jan. 6 Jan. 21 53. Montgomery 320 Feb. 21 Mar. 4 Mar. 11 Mar. 18 Mar. 28 Oct. 28 Nov. 4 Nov. 9 Nov. 14 Nov. 21 (26 years) 280 Jan. 30 Feb. 13 Feb. 22 Mar. 4 Mar. 17 N ov. 4 Nov. 15 Nov. 23 Dec. 1 Dec. 12 240D Jan. 7 Jan. 25 Feb. 6 Feb. 18 Mar. 8 Nov. 14 Nov. 28 Dec. 7 Dec. 17 Dec. 31 200 Jan. 2 Jan. 18 Jan. 31 Feb. 16 Dec. 5 'Dec. 22 Jan. 4 Jan. 21 * 160 * Jan. 19 Feb. 5 Dec. 31 Jan. 31 * * 54. Selma 320 f eb. 23 Mar. 6 Mar. 13 Mar. 21 Apr. 1 Oct. 26 Nov. 5 Nov. 11 Nov. 18 Nov. 28 (26 years) 280 Jan. 23 Feb. 8 Feb. 19 Mar. 2 Mar. 18 Nov. 3 Nov. 16 Nov. 25 Dec. 4 Dec. 17 240 Dec. 13 Jan. 15 Jan. 30 Feb. 14 Mar. 7 Nov. 16 Dec. 1 Dec. 12 Dec. 24 Jan. 18 200 * Dec. 25 Jan. 13 Jan. 26 Feb. 11 Dec. 5 Dec. 24 Jan. 8 Feb. 3 * 160 * * Jan. 18 Feb. 4 Dec. 26 Feb. 1* 55. Union Springs 320 Mar. 2 Mar. 12 Mar. 19 Mar. 26 Apr. 4 Oct. 26 Nov. 3 Nov. 9 Nov. 14 Nov. 22 (25 years) 280 Feb. 4 Feb. 17 Feb. 27 Mar. 9 Mar. 22 N ov. 3 Nov. 13 Nov. 20 Nov. 27 Dec. 7 240 Jan. 21 Feb. 5 Feb. 16 Feb. 26 Mar. 14 Nov. 15 Nov. 28 Dec. 8 Dec. 17 Dec. 30 (Corn'd) 1191 TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Coastal Plain (Cont'd) 58. Brantley (21 years) 59. Chatom (25 years) 60. Clayton (21 years) 61. Frisco City (25 years) 62. Geneva (26 years) 63. Greenville (26 years) 64. Headland (26 years) 65. Highland Home (25 years) 66. Ozark (24 years) 67. Thomasville (26 years) 68. Troy (26 years) Gulf 69. Bay Minette (26 years) 70. Coden (21 years) 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 Mar. 16 Feb. 16 Jan. 30 Jan. 23 Dec. 16 Mar. 14 Feb. 9 Jan. 23 Jan. 1 Feb. 22 Feb. 2277 Jan. 25 Dec. 30 * Feb. 27 Jan. 28 Jan. 4 Dec. 7 * Mar. 4 Jan. 29 Dec. 27 * * Feb. 22 Jan. 26 Dec. 30 * * Feb. 10 Jan. 22 Jan. 1 * Mar. 3 Feb. 4 Jan. 21 Dec. 8 * Feb. 22 Jan. 31 Jan. 9 * * Mar. 9 Jan. 26 Jan. 7 Dec. 7 * Mar. 5 Jan. 26 Dec. 22 * * Feb. 13 Jan. 18 Dec. 13 * * Feb. 11 Jan. 20 Dec. 28 * * Mar. 24 Mar. 1 Feb. 14 Feb. 4 Jan. 14 Mar. 24 Feb. 25 Feb. 8 Jan. 18 * Mar. 6 Feb. 19 Feb. 6 Jan. 19 Mar. 10 Feb. 13 Jan. 22 Jan. 8 * Mar. 13 Feb. 14 Jan. 17 Jan. 2 Mar. 7 Feb. 13 Jan. 23 Jan. 8 Feb. 25 Feb. 8 Jan. 21 Mar. 12 Feb. 18 Feb. 6 Jan. 12 * Mar. 5 Feb. 15 Jan. 26 Jan. 15 Mar. 18 Feb. 13 Jan. 29 Jan. 9 Mar. 12 Feb. 11 Jan. 23 Jan. 8 Feb. 24 Feb. 4 Jan. 13 * * Feb. 24 Feb. 6 Jan. 14 Dec. 14 * Mar. 30 Mar. 10 Feb. 23 Feb. 12 Jan. 24 Mar. 30 Mar. 9 Feb. 20 Jan. 31 Jan. 9 Mar. 14 Feb. 28 Feb. 14 Jan. 31 Jan. 3 Mar. 17 Feb. 24 Feb. 5 Jan. 22 * Mar. 19 Feb. 25 Jan. 29 Jan. 17 Mar. 16 Feb. 25 Feb. 7 Jan. 22 Jan. 8 Mar. 8 Feb. 19 Feb. 2 Jan. 19 Mar. 18 Feb. 28 Feb. 18 Jan. 28 Jan. 13 Mar. 12 Feb. 26 Feb. 8 Jan. 27 * Mar. 24 Feb. 26 Feb. 13 Jan. 24 Jan. 14 Mar. 18 Feb. 23 Feb. 7 Jan. 22 Mar. 4 Feb. 16 Jan. 28 Jan. 5 Mar. 5 Feb. 18 Jan. 26 Jan. 11 * Apr. 5 Mar. 18 Mar. 5 Feb. 20 Feb. 2 Apr. 5 Mar. 20 Mar. 3 Feb. 12 Jan. 24 Mar. 22 Mar. 9 Feb. 22 Feb. 11 Jan. 25 Mar. 24 Mar. 7 Feb. 18 Feb. 4 Jan. 22 Mar. 25 Mar. 7 Feb. 10 Jan. 29 Jan. 19 Mar. 25 Mar. 10 Feb. 21 Feb. 3 Jan. 25 Mar. 19 Mar. 2 Feb. 14 Jan. 29 * I Mar. 25 Mar. 10 Mar. 1 Feb. 12 Jan. 30 Mar. 20 Mar. 8 Feb. 20 Feb. 7 Jan. 18 Mar. 30 Mar. 11 Feb. 28 Feb. 8 Jan. 29 Mar. 23 Mar. 7 Feb. 21 Feb. 3 Jan. 23 Mar. 12 Feb. 28 Feb. 10 Jan. 23 * Mar. 13 Mar. 2 Feb. 6 Jan. 25 Apr. 13 Mar. 31 Mar. 19 Mar. 4 Feb. 15 Apr. 15 Apr. 6 Mar. 20 Mar. 1 Feb. 10 Apr. 2 Mar. 21 Mar. 5 Feb. 27 Feb. 10 Apr. 4 Mar. 23 Mar. 8 Feb. 23 Feb. 5 Apr. 3 Mar. 23 Feb. 28 Feb. 13 Feb. 3 Apr. 7 Mar. 27 Mar. 14 Feb. 20 Feb. 7 Apr. 4 Mar. 18 Mar. 3 Feb. 9 Feb. 2 Apr. 2 Mar. 24 Mar. 17 Mar. 5 Feb. 17 Mar. 30 Mar. 23 Mar. 9 Feb. 22 Feb. 4 Apr. 8 Mar. 30 Mar. 22 Feb. 28 Feb. 14 Mar. 31 Mar 23 Mar. 13 Feb. 20 Feb. 10 Mar. 24 Mar. 17 Mar. 2 Feb. 9 Feb. 1 Mar. 26 Mar. 19 Feb. 24 Feb. 10 Feb. 1 Oct. 18 Oct. 26 Nov. 3 Nov. 15 Nov. 25 Oct. 24 Oct. 28 Nov. 7 Nov. 17 Dec. 10 Nov. 1 Nov. 7 Nov. 24 Dec. 3 Dec. 23 Oct. 27 Nov. 4 Nov. 14 Nov. 27 Dec. 25 Oct. 23 Nov. 3 Nov. 20 Dec. 2 Dec. 31 Oct. 27 Nov. 7 Nov. 13 Nov. 25 Dec. 24 Oct. 28 Nov. 8 Nov. 24 Dec. 12 Dec. 18 Oct. 27 Nov. 5 Nov. 13 Nov. 25 Dec. 22 Oct. 31 Nov. 5 Nov. 15 Dec. 3 Dec. 10 Oct. 26 Nov. 2 Nov. 9 Nov. 24 Dec. 10 Oct. 28 Nov. 7 Nov. 14 Nov. 26 Dec. 19 Oct. 30 Nov. 9 Nov. 23 Dec. 9 Jan. 14 Nov. 3 Nov. 10 Nov. 26 Dec. 17 Dec. 28 Oct. 25 Nov. 3 Nov. 16 Nov. 30 Dec. 16 Nov. 1 Nov. 7 Nov. 21 Dec. 5 Dec. 29 Nov. 9 Nov. 19 Dec. 8 Dec. 20 Jan. 11 Nov. 5 Nov. 17 Nov. 27 Dec. 15 Jan. 15 Nov. 1 Nov. 16 Dec. 2 Dec. 23 Jan. 25 Nov. 7 Nov. 18 Nov. 27 Dec. 17 Jan. 15 Nov. 6 Nov. 21 Dec. 9 Jan. 2 Nov. 5 Nov. 17 Nov. 25 Dec. 15 Jan. 10 Nov. 8 Nov. 17 Dec. 2 Dec. 23 Jan. 13 Nov. 3 Nov. 14 Nov. 25 Dec. 11 Jan. 1 Nov. 7 Nov. 19 Nov. 27 Dec. 17 Jan. 23 Nov. 11 Nov. 23 Dec. 10 Jan. 4 Nov. 12 Nov. 24 Dec. 11 Jan. 2 ~~II= Oct. 30 Nov. 8 Nov. 25 Dec. 11 Dec. 31 Nov. 6 Nov. 14 Nov. 30 Dec. 17 Jan. 15 Nov. 14 Nov. 28 Dec. 17 Jan. 1 Jan. 31 Nov. 11 Nov. 25 Dec. 5 Dec. 27 Nov. 7 Nov. 24 Dec. 10 Jan. 9 Nov. 14 Nov. 26 Dec. 7 Jan. 1 Nov. 12 Nov. 30 Dec. 19 Jan. 20 * Nov. 11 Nov. 26 Dec. 4 Dec. 28 Jan. 28 Nov. 13 Nov. 25 Dec. 14 Jan. 7 * Nov. 8 Nov. 22 Dec. 6 Dec. 23 Jan. 25 Nov. 15 Nov. 27 Dec. 7 Jan. 2 Nov. 20 Dec. 2 Dec. 22 Feb. 1 Nov. 18 Dec. 3 Dec. 21 Jan. 14 Nov. 4 Nov. 13 Dec. 5 Dec. 22 Jan. 16 Nov. 11 Nov. 21 Dec. 10 Dec. 30 * Nov. 20 Dec. 7 Dec. 27 Jan. 14 Nov. 18 Dec. 3 Dec. 14 Jan. 9 Nov. 13 Dec. 3 Dec. 19 Jan. 30 * Nov. 21 Dec. 3 Dec. 17 Jan. 18 * Nov. 19 Dec. 9 Dec. 29 * Nov. 17 Dec. 5 Dec. 12 Jan. 12 Nov. 19 Dec. 4 Dec. 26 Jan. 26 Nov. 13 Dec. 1 Dec. 17 Jan. 5 Nov. 22 Dec. 5 Dec. 17 Jan. 19 Nov. 29 Dec. 11 Jan. 4 Nov. 24 Dec. 13 Dec. 31 Feb. 2 Nov. 12 Nov. 20 Dec. 18 Jan. 7 Feb. 12 Nov. 19 Dec. 1 Dec. 23 Jan. 17 * Nov. 27 Dec. 19 Jan. 10 Feb. 4 * Nov. 26 Dec. 16 Dec. 27 Feb. 7 * Nov. 22 Dec. 16 Jan. 2 * * Dec. 2 Dec. 15 Jan. 3 * Nov. 28 Dec. 23 Jan. 16 * * Nov. 26 Dec. 18 Dec. 25 Feb. 14 * Nov. 27 Dec. 15 Jan. 15 * * Nov. 21 Dec. 13 Jan. 1 Jan. 31 Dec. 2 Dec. 216 Dec. 16 Jan. 7 * * Dec. 12 Dec. 25 Jan. 31 * * Dec. 3 Dec. 27 Jan. 15 * * (Cont d) [20] TABLE 6. (Cont'd) PROBABILITY OF SPRING AND FALL TEMPERATURE THRESHOLDS Percent probability of Percent probability of indicated temperature indicated temperature (or lower) occurring after date in spring (or lower) occurring before date in fall Station Temp. 90% 70% 50% 30% 10% 10% 30% 50% 70% 90% Gulf (Cont'd) 71. Fairhope (29 years) 72. Fort Morgan (27 years) 73. Mobile (25 years) 74. Robertsdale (29 years) 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 320 280 240 200 160 Feb. 2 Jan. 3 * S* * * * * Feb. 6 Jan. 10 * * * Feb. 15 Jan. 23 * * * Feb. 17 Jan. 25 Jan. 6 * * Jan. 3 * Feb. 19 Jan. 27 Jan. 4 * Feb. 27 Feb. 9 Jan. 7 * * Feb. 27 Feb. 8 Jan. 20 * * Jan. 27 Dec. 22 * * * Feb. 28 Feb. 8 Jan. 17 * * Mar. 8 Feb. 21 Jan. 22 * * Mar. 8 Feb. 21 Feb. 2 Jan. 17 * Feb. 13 Jan. 18 * * * Mar. 9 Feb. 19 Jan. 28 Jan. 9 Mar. 17 Mar. 174 Mar. 4 Feb. 5 Jan. 22 * Mar. 23 Mar. 12 Feb. 21 Feb. 4 Jan. 26 Mar. 7 Feb. 9 Jan. 24 Jan. 23 Jan. 17 Mar. 21 Mar. 8 Feb. 12 Feb. 1 Jan. 29 Mar. 29 Mar. 21 Feb. 24 Feb. 4 Jan. 31 Nov. 3 Nov. 15 Nov. 25 Dec. 26 Jan. 17 Nov. 29 Dec. 11 Dec. 28 * Nov. 3 Nov. 12 Dec. 1 Dec. 20 Jan. 25 Oct. 26 Nov. 7 Nov. 22 Dec. 9 * Nov. 15 Nov. 28 Dec. 15 Jan. 16 Dec. 20 Jan. 4 * * * Nov. 17 Nov. 28 Dec. 18 Jan. 11 * Nov. 9 Nov. 21 Dec. 9 * * Nov. 23 Dec. 7 Dec. 30 * Jan. 5 Feb. 3 * Nov. 26 Dec. 9 Dec. 31 * * Nov. 19 Nov. 30 Dec. 21 * Dec. 1 Dec. 17 Jan. 15 Jan. 26 * * * * Dec. 5 Dec. 20 Jan. 16 * * Nov. 28 Dec. 10 Jan. 3 * * *Selected probability value greater than probability of temperature threshold being reached at all during the season. [21] Dec. 13 Jan. 2 * * * * * S * * Dec. 19 Jan. 5 * * Dec. 12 Dec. 24 * * * Oct. 20 Oct 20 UDERDA LIMESTONE MADISON JACKSON Oct. 25 Oct. 30 BERT 0 cf. 3 RENCE Oct. 0 DEKALB Oct. 25 Nov. 5 FRAN IN MORGAN 0 Nov. 5 MARION WINSTON OKEE BL T ETOWAH R WALKER HCXJN F TTE T. CLAIR Oc .25 JEF RSON ct. 25 TUSCAL TALL PICKFNS ov. 5 SHELBY Oct. 30 t BIBB Nov. 5 COOSA TALLAPOOSA CH S GREENE HILTON HALE SUMTER PERRY ri J AUTAUGA ELMOR E Nov. 10 MACON MARENGO ALLAS RUSSEL MONTGOMERY CHOCT L Es BULL= WILCOY BARBOUR Nov. 15 CLARKE BUTLER CRENSHAW E Nov. 5 MONROE WA H RY CONECUH FFEE DALE Nov. I COVIN ON ESCAMBIA Nov.5 H STON IN GENEVA Nov. 15 FIG. 3. Mean date of first 32*F freeze in the fall. [221 Worm Cold Nov. 10 FIG. 4. Dates in the fall before which there is a 20 percent chance of a 32 0 F freeze. [23] Oct. Oct. Nov. Nov. Apr 15- /Apr. 15 Apr. 10 Apr. 5 Apr.15 RT pr RENCE EKAL A r1Apr.1 F KLIN io Apr2 A pr. 10 MARION WINETON CULLMAN KEE OWAH BLOUN .5 WALKER WALKERCALHOUN A TEST. CLAIR JEFFERSON Apr 10 T OOSA TALL Apr.5 SHELBYAH p5 Apr. 15 SAp 10 Mo r. 3 0 A r. 10 COOSA TALLAPOOSA CHAMBERS GREENE CHILTON HLE Ma0r. 30 SUMTER PERPY Mar. 25 ELMORE LEE AUTAUGA MACON MARENGO ALLAS RUS ELL ONT MERY CHOCTA BULLOC Mar. 30 WILCOX RouR LARKE MO f. I CRENSHAW PIKE MONROE Mar. 30 1 'TON r. RY Mor..15 CONECUH F C FFEE DALE Mar. 25COIGOMa.1 HOUSTON Mar. 20 DWI ll ESCAM IAGENEV) Mor.. ,Mor FIG. 5. Mean date of last 32*F freeze in the spring. [24] \ Mar. 25Mar. 20 Worm Z Cold Mar. 15 FIG. 6. Dates in the spring after which there is a 20 percent chance of a 32*F freeze. [25] Oct. 30 O~ct.30 Nov. 5 LMESTON j (I X4JACKSON ~~Dec. 5 Dec. 10 Warm Cold FIG. 7. Mean date of first 28*F freeze in the fall. [261 Nov. 5 ,Nov. 5 ,Nov. 5 .Nov. 10 N ov. 1 11 Nov. 2 Nov. 34 Dec. ' Nov. 25 Nov. 30 30 .Oct. 20 SNov.15 Nov. 20 Worm Nov. 15 Nov. 15 LI1 Cold FIG. 8. Dates in the fall before which there is a 20 percent chance of a 28OF freeze. [27] Oct. Oct. Oct. 3( 25 25 .Oct.30 5 10 Nov. 5 Nov. 20 Mar. 15 ,. Mar. 10 Mar. War~m FIG. 9. Mean date of last 28OF freeze in the spring. [281 Mar. 30. Mar. 25' Mar. 20- Mar. Mar. -Mar. 30 -Apr. 5 ,Apr. 5 30 Mar.5. Feb. 28. Feb. 134' Feb. 8'lo -Feb. 28 Feb. 23 Feb. 23 Cold CL E PIKE Mar.20 ROE Mar. 25 WASHIN ONHENRY M r.15 UH COF E DALE Mar. 20 r. 15 ovMar. 10 M r. 20 HOUSTON MOBILE Ma .2 Mar. 10 or. Mar. 10 Feb. 28 ' Mar.o10 Worm Cold Feb. 28 FIG. 10. Dates in spring after which there is a 20 percent chance of a 28*F freeze. [29] 50% 1 J $%Worm Cold 30% - 80% 0 50% 30% FIG. 11..Probability of a 24*F freeze or colder occurring sometime during cold season. [30] 50% IWrm 70% 1 Cold FIG. 12. Probability of a 20*F freeze or colder occurring sometime during cold season. [31] 100% 0% 80% 90%.-1 80% - 70%- 60% 50%" 40%" I I \ \ \ U\U ' - I I I 100% 0-0" CALM N 100% FAYETT EBURNE .0000' TUSCALOOSA 90% TAdADEGA :NS I.HJEL CLAY RANDOLPH 100% 95% BIBB 90% J-- GREENE COOSA S C ERS 801 HALE LEE MACON MARENGO LAS RUS ELL TGO Y BULLOCK WILCOX 0 0 BARBOUR CLARKE ER ;:riAW PIKE ONROE 1:1 Y 6( C FFEE DALE 51 4 50% COVINGTON 0% 31 HOUSTON ESCAMBIA IN GENEV .30% 0% \ 40% 0% 30% 20 0 Worm Cold 15% FIG. 13. Probability of a 16*F freeze or colder occurring sometime during cold season. APPENDIX I Appendix Table 1. Mean Day Number, Standard Deviation, and Probability of Temperature Occurrence Last in spring First in fall Station 160 200 240 280 320 320 280 240 200 160 Northern Valley 1. Athens ....... Mean SD P 2. Belle Mina .... Mean SD P 3. Falkville ...... Mean SD P 4. Florence ..... Mean SD P 5. Madison ..... Mean SD P 6. Moulton ... . Mean SD P 7. Muscle Mean Shoals ..... SD P 8. Red Bay ...... Mean SD P. 9. Redstone Mean Arsenal .... SD P 10. Russeliville ... Mean SD P 11. Waterloo ..... Mean SD P Appalachian Mtn. 12. Albertville .... Mean SD P 13. Bessemer ..... Mean SD P 14. Birmingham . . Mean SD P 15. Bridgeport .... Mean SD P 16. Crossville ..... Mean SD P 17. Guntersville . . Mean SD P 18. Oneonta ..... Mean SD P 19. Saint Mean Bernard ...... SD P 41.8 55.1 73.1 87.1 98.3 23.4 18.4 16.7 8.2 10.4 1.000 1.000 1.000 1.000 1.000 32.2 45.8 60.0 79.0 94.1 24.9 21.2 23.8 19.2 12.2 0.960 1.000 1.000 1.000 1.000 38.6 50.7 62.6 85.8 98.2 21.0 17.7 20.9 11.6 7.9 1.000 1.000 1.000 1.000 1.000 41.1 55.8 72.4 87.1 96.3 20.8 21.4 19.3 13.2 13.0 1.000 1.000 1.000 1.000 1.000 40.1 49.2 65.6 81.6 96.3 20.7 23.5 21.9 13.5 9.1 0.931 1.000. 1.000 1.000 1.000 37.5 54.1 63.6 81.7 96.9 18.9 15.6 17.7 9.5 7.9 1.000 1.000 1.000 1.000 1.000 29.9 41.9 52.7 75.0 84.6 21.3 22.9 24.8 12.2 12.3 0.923 0.962 1.000 1.000 1.000 38.0 52.9 64.4 77.4 92.5 18.6 15.5 15.6 10.2 9.1 S1.000 1.000" 1.000" 1.000 1.000 37.3 49.2 67.1 80.2 95.9 21.4 19.0 18.9 16.4 12.8 0.957 1.000 1.000 1.000 1.000 50.6 61.6 78.9 90.0 105.9 20.9 20.7 9.3 10.1 12.9 1.000 1.000 1.000 1.000 1.000 47.0 55.6 77.0 94.2 105.5 22.1 22.4 17.8 9.3 12.2 1.000 1.000 1.000 1.000 1.000 33.8 48.8 61.9 79.2 92.9 24.6 22.6 21.3 12.0 9.1 0.960 1.000 1.000 1.000 1.000 30.5 47.7 64.6 77.4 92.4 26.5 23.7 16.1 12.8 12.5 0.957 1.000 1.000 1.000 1.000 29.0 37.8 54.6 71.5 90.3 22.8 25.8 20.6 19.4 11.4 0.800 0.960 1.000 1.000 1.000 45.3 59.3 75.0 92.0 102.1 19.8 19.4 15.0 9.7 9.5 1.000 1.000 1.000 1.000 1.000 39.8 50.8 61.4 84.5 95.7 25.6 24.1 19.3 11.3 8.0 0.960 1.000 1.000 1.000 1.000 32.3 45.4 60.5 76.0 91.4 24.6 20.2 20.3 18.4 11.5 1.000 1.000 1.000 1.000 1.000 33.2 47.2 68.0 88.1 99.3 28.4 25.2 15.2 10.5 10.6 0.885 1.000 1.000 1.000 1.000 41.3 54.8 72.4 87.8 99.1 23.7 22.1 14.6 11.0 10.2 0.960 1.000 1.000 1.000 1.000 300.6 309.3 317.9 336.8 350.4 11.3 13.2 10.2 16.6 16.1 1.000 1.000 1.000 1.000 1.000 302.6 309.3 320.2 338.4 356.6 10.1 9.3 11.7 16.3 18.7 1.000 1.000 1.000 1.000 0.960 299.7 309.6 321.9 338.7 355.0 11.5 12.0 10.8 15.2 17.8 1.000 1.000 1.000 1.000 1.000 297.1 310.8 319.9 333.8 350.0 9.0 12.8 11.7 14.0 22.9 1.000 1.000 1.000 1.000 1.000 303.5 309.4 322.9 334.6 346.9 7.6 9.2 12.2 16.6 17.4 1.000 1.000 1.000 1.000 0.931 / 300.1 310.7 319.6 337.0 350.1 11.5 9.7 10.9 14.6 17.1 1.000 1.000 1.000 1.000 1.000 305.7 311.3 327.3 340.2 362.2 8.9 11.5 16.6 21.0 24.4 1.000 1.000 1.000 0.962 0.885 309.8 317.8 329.4 342.1 357.8 20.7 13.0 14.8 8.8 8.1 1.000 1.000' 1.000 "1.000 1.000 300.0 308.0 318.1 336.5 342.4 10.0 8.5 11.5 15.6 16.2 1.000 1.000 1.000 1.000 1.000 298.7 305.2 313.2 325.7 336.4 12.6 8.4 10.6 16.6 17.7 1.000 1.000 1.000 1.000 1.000 294.3 303.4 317.6 331.6 344.3 11.6 13.7 11.9 19.4 17.0 1.000 1.000 1.000 1.000 1.000 304.2 313.8 326.9 340.2 357.8 11.5 10.7 16.8 16.7 22.4 1.000 1.000 1.000 1.000 0.960 305.5 309.1 325.7 343.5 364.1 8.1 9.8 16.6 18.9 24.2 1.000 1.000 1.000 1.000 0.957 308.0 315.6 331.8 352.1 363.3 8.4 11.2 15.2 17.9 21.2 1.000 1.000 1.000 0.960 0.800 297.3 305.4 318.0 326.9 345.4 11.6 8.3 12.0 10.8 17.1 1.000 1.000 1.000 1.000 1.000 301.6 308.8 315.8 338.2 347.5 9.5 12.0 10.8 16.8 19.1 1.000 1.000 1.000 1.000 0.960 308.7 317.0 330.2 341.9 363.1 8.2 12.2 14.1 12.6 24.3 1.000 1.000 1.000 1.000 1.000 299.7 308.3 319.5 338.5 353.5 10.4 9.9 16.1 22.6 21.6 1.000 1.000 1.000 1.000 0.885 302.0 310.4 320.7 335.2 347.2 9.3 10.0 13.5 16.5 19.2 1.000 1.000 1.000 1.000 0.960 (Cont'd) [33] Appendix Table 1. (Con't) Mean Day Number, Standard Deviation, and Probability of Temperature Occurrence Last in spring First in fall Station 160 200 240 280 320 320 280 240 200 160 20. Scottsboro .... Mean SD P 21. Valley Head .. Mean SD P Upper Plains 22. Bankhead .. :. Mean L&D SD P 23. Centreville ... Mean SD P 24. Clanton ...... Mean SD P 25. Double Mean Springs .... SD P 26. Fayette ....... Mean SD PL 27. Haleyville .... Mean SD P 28. Hamilton ..... Mean SD P 29. Prattville ..... Mean SD P 30. Tuscaloosa .... Mean SD. P 31. Vernon ....... Mean SD P Eastern Valley 32.- Anniston ..... Mean SD P 33. Calera ........ Mean SD P 34. Centre ....... .Mean SD P 35. Childersburg.. Mean SD P 36. Gadsden ..... Mean SD P 37. Sylacauga ..... Mean SD P 38. Talladega ..... Mean SD P 40.4 54.6 72.8 86.4 99.3 20.6 18.7 14.1 12.3 10.1 0.960 1.000 1.000 1.000 1.000 46.3 65.7 86.0 98.2 110.9 25.4 17.9 14.7 9.2 10.6 1.000 1.000 1.000 1.000 1.000 34.3 44.8 62.0 72.5 90.2 20.1 24.7 14.1 15.4 10.4 0.900 1.000 1.000 1.000 1.000 33.9 44.9 53.8 74.6 94.5 24.9 21.2 24.6 11.9 10.0 0.885 0.923 1.000 1.000 1.000 23.3 35.7 59.3 72.0 89.7 22.1 27.7 15.8 16.8 10.0 0.962 1.000 1.000 1.000 1.000 47.4 57.0 73.5 90.6 97.7 20.0 19.3 14.2 10.8 9.3 1.000 1.000 1.000 1.000 1.000 29.1 47.0 63.3 78.0. 97.4 25.8 23.5 15.7 14.7 10.3 0.920 1.000 1.000 1.000 1.000 40.3 52.0 66.2 81.3 96.7 24.1 23.5 16.0 12.1 9.3 0.885 1.000 1.000 1.000 1.000 56.1 61.9 75.7 89.8 103.9 16.1 18.3 19.3 11.6 9.6 1.000 1.000 1.000 1.000 1.000 30.5 29.6 47.0 65.9 80.5 15.6 22.2 24.4 20.1 10.9 0.577 0.962 1.000 1.000 1.000 24.5 31.6 47.7 70.6 86.2 .19.6 . 26.6 21.6 15.3 , 114 1.000 1.000 1.000 1.000 1.000 45.6 53.6 66.7 86.2 101.9 22.0 20.9 18.9 12.0 11.7 1.000 1.000 1.000 1.000 1.000 26.9 41.3 57.6 77.7 91.0 22.0 21.8 20.5 13.9 10.8 0.880 0.960 1.000 1.000 1.000 35.2 53.2 69.0 86.5 99.6 26.1 19.5 16.0 12.1 13.5 1.000 1.000 1.000 1.000 1.000 34.9 45.2 63.2 83.8 93.5 21.5 16.8 20.5 12.2 10.7 0.952 1.000 1.000 1.000 1.000 39.6 48.6 64.9 79.1 95.4 20.6 16.3 15.4 16.2 9.5 1.000 1.000 1.000 1.000 1.000 32.5 42.2 65.6 79.8 96.7 20.2 23.5 17.1 13.0 10.5 0.917 1.000 1.000 1.000 1.000 40.3 50.6 66.2 78.6 98.0 19.5 19.2 15.2 12.7 8.3 1.000 1.000 1.000 1.000 1.000 37.5 42.2 67.1 86.2 97.8 27.5 23.3 19.3 11.3 11.4 0.885 1.000 1.000 1.000 1.000 299.9 307.4 316.3 329.3 345.0 11.4 8.6 11.9 16.3 20.5 1.000 .1.000 1.000 1.000 0.960 293.9 303.0 309.2 322.5 340.3 10.3 8.4 9.9 14.8 21.8 1.000 1.000 1.000 1.000 1.000 308.6 319.6 336.9 351.4 365.6 9.5 13.3 15.8 17.4 20.3 1.000 1.000 1.000 1.000 0.950 304.6 313.8 329.3 340.7 354.4 8.3 13.8 16.8 16.7 25.0 1.000 1.000 1.000 0.923 0.846 304.3 312.0 327.1 341.6 366.1 25.0 14.7 18.1 10.2 8.6 1.000 1.000 1.000 1.000 0.962 303.5 310.5 321.7 334.6 348.9 11.4 9.5 13.1 15.1 16.7 1.000 1.000 1.000 1.000 1.000 300.2 310.5 319.6 337.9 352.7 9.8 11.4 11.5 18.2 20.6 1.000 1.000 1.000 1.000 0.920 303.2 313.3 325.5 338.4 347.1 9.6 11.2 13.7 20.2 16.6 1.000 1.000 1.000 1.000 0.885 295.1 308.1 315.1 323.0 345.7 11.6 9.7 12.2 11.5 19.5 1.000 1.000 1.000 1.000 1.000 309.8 322.7 334.7 353.0 368.9 23.6 20.7 15.7 13.0 9.6 1.000 1.000 1.000 0.962 0.577 305.5 315.2 334.5 349.3 362.6 8.2 14.1 17.7 19.0 20.3 1.000 1.000 1.000 1.000 1.000 297.3 306.4 315.9 331.1 345.7 10.2 8.6 11.8 15.9 15.6 1.000 1.000 1.000 1.000 1.000 305.5 313.1 327.0 341.5 363.7 8.5 10.7 16.5 17.2 21.8 1.000 1.000 1.000 0.960 0.880 301.0 309.0 318.2 334.9 353.7 10.5 11.3 12.9 15.9 21.7 1.000 1.000 1.000 1.000 1.000 301.1 310.7 322.1 339.4 356.8 9.9 9.2 13.0 17.9 19.4 1.000 1.000 1.000 1.000 0.905 301.7 310.2 321.1 338.9 360.1 11.5 9.2 11.4 16.1 21.9 1.000 1.000 1.000 1.000 1.000 303.2 309.6 319.5 339.8 366.5 8.9 9.2 12.7 17.0 27.8 1.000 1.000 1.000 1.000 0.875 301.9 312.3 322.3 334.1 359.5 12.6 12.5 12.0 17.0 22.1 1.000 1.000 1.000 1.000 1.000 301.5 311.2 323.1 339.3 362.5 8.3 13.1 14.7 15.3 25.1 1.000 1.000 1.000 1.000 0.885 (Cont'd) [34] Appendix Table 1. (Cont'd) Mean Day Number, Standard Deviation, and Probability of Temperature Occurrence Last in spring First in fall Station 160 200 240 280 320. 320 280 240 200 160 Piedmont Plateau 39. Auburn ...... Mean SD P 40. Ashland ...... Mean SD P 41. Camp Hill .... Mean SD P 42. Heflin ........ Mean SD P 43. LaFayette ..... Mean SD P 44. Martin Dam... Mean SD P 45. Rockford ..... Mean SD P 46. Rock Mills .... Mean SD P Prairie 47. Dayton ....... Mean SD P 48. Demopolis Mean L&D ....... SD P 49. Greensboro .. Mean SD P 50. Livingston .... Mean SD P 51. Marion Mean Junction ... SD P 52. Minter ........ Mean SD P 53. Montgomery.. Mean SD P 54. Selma ........ Mean SD P 55. Union Mean Springs .... SD P Coastal Plain 56. Andalusia .... Mean SD P 57. Brewton ...... Mean SD P 58. Brantley ...... .Mean SD P 27.8 38.7 52.0 69.5 87.0 22.1 25.3 20.4 20.3 11.1 0.769 1.000 1.000 1.000 1.000 37.3 51.4 64.8 81.3 94.0 19.1 16.0 18.6 14.7 9.4 1.000 1.000 1.000 1.000 1.000 36.8 44.8 61.4 79.4 96.0 24.3 22.9 21.4 20.1 12.2 0.960 1.000 1.000 1.000 1.000 48.0 63.2 77.8 95.4 107.5 18.8 16.9 16.3 11.9 14.0 1.000 1.000 1.000 1.000 1.000 28.9 43.6 50.8 70.8 88.5 25.7 26.0 24.6 16.9 12.0 0.862 0.966 1.000 1.000 1.000 25.0 25.4 45.7 62.9 84.9 18.0 23.9 23.3 17.0 13.6 0.615 0.885 1.000 1.000 1.000 37.8 50.4 67.4 82.3 95.6 23.1 22.9 15.2 11.1 10.5. 1.000 1.000 1.000 1.000 1.000 32.5 47.1 65.8 83.2 99.6 23.4 27.7 17.3 12.0 10.9 0.923 0.962 1.000 1.000 1.000 27.9 33.1 46.0 62.3 79.3 16.4 27.6 24.1 18.8 11.7 0.640 1.000 1.000 1.000 1.000 21.9 24.8 44.5 61.6 77.8 18.7 24.5 24.9 16.9 14.6 0.640 1.000 1.000 1.000 1.000 21.0 36.5 50.3 64.0 81.4 20.2 29.7 22.6 15.6 12.8 0.680 1.000 1.000 1.000 1.000 20.0 33.4 51.2 66.7 88.1 18.6 25.8 18.7 16.8 10.5 0.870 1.000 1.000 1.000 1.000 25.8 30.2 51.8 66.3 81.1 18.9 25.2 17.8 15.2 12.9 0.667 0.963 1.000 1.000 1.000 30.1 32.2 55.9 63.6 74.9 18.0 22.0 17.8 15.9 14.9 0.750 0.900 1.000 1.000 1.000 28.1 24.4 36.8 53.2 69.9 12.0 19.8 23.4 17.8 13.5 0.385 0.808 1.000 1.000 1.000 25.7 20.3 33.1 50.2 72.5 13.3 19.4 26.3 21.0 14.3 0.423 0.769 0.923 1.000 1.000 22.2 26.6 46.8 58.0 77.7 19.5 29.0 20.2 18.1 13.0 0.692 1.000 1.000 1.000 1.000 28.0 35.5 41.4 60.5 79.6 13.2 19.4 29.2 20.2 16.1 0.480 0.840 1.000 1.000 1.000 27.8 31.2 46.7 68.4 89.4 13.9 25.4 25.0 22.0 10.7 0.615 0.923 1.000 1.000 1.000 26.1 43.3 54.4 68.5 89.0 16.6 15.5 18.8 17.1 11.2 0.905 1.000 1.000 1.000 1.000 309.3 319.9 334.5 347.9 358.9 10.7 16.8 17.3 22.7 22.7 1.000 1.000 1.000 1.000 0.769 308.3 316.3 327.4 342.5 351.8 9.9 12.2 15.3 14.5 18.9 1.000 1.000 1.000 1.000 1.000 300.4 310.9 323.4 338.8 359.8 10.0 9.6 14.3 15.6 24.4 1.000 1.000 1.000 1.000 0.960 294.0 304.4 312.3 323.5 343.1 11.0 7.7 9.0 13.5 12.1 1.000 1.000 1.000 1.000 0.952 308.5 313.4 338.9 345.4 363.5 26.1 16.5 16.1 8.2 9.7 1.000 1.000 1.000 0.966 0.862 316.4 328.6 350.0 362.5 369.8 13.1 17.2 18.0 20.4 21.1 1.000 1.000 1.000 0.885 0.615 302.8 310.2 323.9 339.7 356.5 10.8 10.6 15.0 16.9 25.0 1.000 1.000 1.000 1.000 1.000 301.6 310.2 321.7 335.3 359.0 8.9 7.7 12.8 16.2 24.3 1.000 1.000 1.000 0.962 0.923 310.3 323.2 334.8 356.7 370.5 8.5 12.8 15.9 21.6 17.7 1.000 1.000 1.000 1.000 0.640 309.7 320.7 336.4 351.6 366.0 10.0 16.4 21.2 24.1 16.5 1.000 1.000 1.000 1.000 0.640 312.1 328.0 338.2 353.9 359.8 9.5 17.2 15.4 20.7 17.0 1.000 1.000 1.000 1.000 0.680 304.7 316.5 329.7 339.6 358.9 11.9 11.5 15.7 16.5 20.0 1.000 1.000 1.000 1.000 0.870 307.3 316.1 328.5 341.9 357.0 8.8 10.2 18.6 18.7 19.8 1.000 1.000 1.000 1.000 0.704 314.5 322.5 338.2 351.3 365.3 11.1 12.7 15.8 22.8 17.7 1.000 1.000 1.000 0.900 0.800 313.0 327.0 341.4 362.7 378.9 9.4 15.1 18.4 20.8 21.9 1.000 1.000 1.000 0.808 0.385 315.4 329.2 344.0 362.6 376.9 12.8 17.4 19.7 21.2 25.7 1.000 1.000 0.923 0.731 0.385 312.6 323.8 341.6 359.2 367.9 21.1 23.4 17.4 13.5 10.7 1.000 1.000 1.000 1.000 0.654 312.9 323.4 337.3 359.4 369.3 12.6 13.5 16.6 23.1 22.8 1.000 1.000 1.000 0.840 0.440 301.9 312.8 331.7 345.2 369.0 8.7 11.8 17.7 21.6 24.5 1.000 1.000 1.000 0.923 0.577 303.3 311.7 329.2 345.2 363.4 9.9 9.7 17.7 20.8 27.7 1.000 1.000 1.000 1.000 0.952 (Cont'd) [35] Appendix Table 1. (Cont'd) Mean Day Number, Standard Deviation, and Probability of Temperature Occurrence Last in spring First in fall Station 160 200 240 280 320 320 280 24'0 200 160 59. Chatom....... Mean SD p 60. Clayton....... Mean SD p 61. Frisco City .... Mean SD p 62. Geneva....... Mean SD p 63. Greenville . ... Mean SD p 64. Headland . Mean SD p 65. Highland Mean Home..SD p 66. Ozark......... Mean SD p 67. Thomasville ... Mean SD p 68. Troy.......... Mean SD p Gulf 69. Bay Mean Minette .... SD 70. Coden........ Mean SD p 71. Fairhope... Mean SD p 72. Fort Morgan . . Mean SD p 73. Mobile........ Mean SD p 74. Robertsdale . Mean SD p 20.7 30.5 50.6 19.4 22.9 21.8 0.680 1.000 1.000 28.2 32.0 45.0 15.0 21.1 15.2 0.524 0.952 1.000 25.8 24.4 35.5 13.0 23.9 24.9 0.480 0.920 1.000 25.4 22.6 30.4 11.4 18.5 -22.5 0.423 0.808 0.962 26.5 25.5 39.4 12.8 21.3 26.4 0.538 0.885 0.962 26.4 27.0 34.5 18.0 12.6 22.1 0.280 0.680 0.960 28.3 31.0 48.5 19.6 26.7. 21.5 0.640 0.920 1.000 23.8 30.8 38.6 13.8 18.8 23.3 0.458 0.875 1.000 28.8 27.2 44.1 16.7 25.9 28.7 0.615 0.923 1.000 28.9 25.4 40.8 15.3 21.2 25.6 0.462 0.885 0.923 28.1 22.0 30.1 11.2 18.6 24.6 0.269 0.615 0.923 29.4 20.9 25.5 11.6 18.9 22.8 0.238 0.714 1.000 25.8 23.5 23.5 8.9 14.9 23.1 0.207 0.448 0.897 21.3 24.2 20.6 8.0 8.5 15.1 0.160 0.227 0.318 29.2 17.7 21.2 11.4 18.4 18.2 0.200 0.440 0.840l 28.4 25.5 25.5 10.6 12.0 24.3 0.241 0.483 0.897 67.8 21.8 1.000 59.0 16.4 1.000 55.0 20.9 1.000 55.6 20.5 1.000 56.3 23.3 1.000 49.9 21.5 1.000 59.1 18.8 1.000 56.6 19.6 1.000 57.3 24.6 1.000 54.1 22.1 1.000 47.3 22.7 1.000 49.0 22.3 1.000 40.1 24.7 0.966 21.4 21.1 0.682 38.6 22.3 1.000 51.8 22.3 1.000 89.1 12.2 1.000 72.5 15.3 1.000 76.1 13.8 1.000 78.0 11.8 1.000 75.4 17.2 1.000 67.4 20.8 1.000 77.4 11.7 1.000 71.4 14.0 1.000 82.9 11.6 1.000 76.8 10.3 1.000 310.2 317.6 334.3 -351.3- 366.2 10.0 13.2 18.0 23.9 21.5 1.000 1.000 1.000 1.000 0.680 318.3 332.1 351.5 364.8 374.4 10.2 16.6 18.3 21.9 19.0 1.000 1.000 1.000 0.952 0.571 315.4 329.0 339.5 358.7 374.4 11.7 16.1 17.1 22.1 18.6 1.000 1.000 1.000 0.920 0.480 311.1 328.4 343.5 365.8 376.8 11.5 16.9 15.3 26.1 17.7 1.000 1.000 0.962 0.808 0.385 317.9 329.7 339.6 361.6 375.3 14.1 14.7 18.3 26.6 20.4 1.000 1.000 0.962 0.885 0.500 316.5 334.3 351.9 370.3 359.9 12.0 17.3 18.8 22.9 22.5 1.000 1.000 0.960 0.680 0.280 315.1 330.2 337.8 359.8 376.9 11.8 16.8 16.3 24.7 21.1 1.000 1.000 1.000 0.920 0.640 317.4 329.5 346.7 366.3 362.9 10.8 15.6 21.6 24.6 26.4 1.000 1.000 0.958 0.833 0.417 312.0 326.4 339.8 354.7 365.2 9.8 16..0 20.5 21.2 22.4 1.000 1.000 1.000 0.923 0.577 318.7 330.7 339.0 362.5 372.8 13.8 15.4 17.0 26.5 27.8 1.000 1.000 0.923 0.885 0.423 324.2 336.0 353.6 367.5 382.7 16.8 17.6 21.7 26.3 22.5 101.M .000 0.9N3 0.577 0.231 322.2 337.5 355.1 371.7 369.8 11.6 18.2 19.7 18.6 19.7 1.000 1.000 1.000 0.762 0.286 327.0 340.6 360.3 373.5 383.2- 15.9 17.5 25.5 17.6 20.0 1.000 0.966 0.897 0.448 0.207 361.2 365.4 368.9 372.5 353.5 24.5 22.6 26.0 36.1 9.2 0.84 0.577 0.269 0.080 0.077 330.0 343.2 360.2 365.0 381.3 17.6 21.1 21.2 16.1 27.3 1.000 1.00 0.840 0.400 0.160 322.7 334.4 351.6 339.6 363.7 18.5 18.0 21.3 15.5 29.7 1.000 1.000 0.897 0.172 0.103 63.4 15.4 1.000 63.7 16.8 1.000 57.5 18.8 1.000 35.7 26.2 0.880 58.9 16.7 1.000 66.9 16.7 1.000 Mean - Mean Day Number beginning with January 1 as Day Number 1 (Occasionally extending to values greater than 365 for low thresholds in the Fall)' SD - Standard Deviation P - Probability of Temperature Occurrence during the year. [36]