WEATHER INFORMATION
The 2001 crop year for Dawson County was another very dry year with the bulk of the dryland cotton acres being failed out. The years total rain fall was only 10.19 inches, with only 5.81 inches from May thru October. Heat units for the growing season were above the 68 year long term accumulation by 278 heat units (May - October).
Irrigated crops were average or above for most producers, some experienced lower yields due to limited irrigation water.
The harvest weather was open and clear for the most part.
As all ways we were glad 2001 crop year was over, and hopefully looking for better days during 2002.
Climate of Lamesa, Texas and Dawson County
Lamesa is located on the high, level South Plains region of Northwest Texas, at an elevation of 2965 feet. It is near the center of Dawson County, and about eleven miles west of the Caprock Escarpment. Sulfur Springs Draw is oriented northwest to southeast across Dawson County, and runs through Lamesa. Fertile loam to sandy loam soils cover most of the Plains area of the county with some sandy lands in the western part. Lamesa is the center of a rich crop-livestock area.
The climate of Lamesa is semi-arid. It is characterized by extreme variability both in rainfall amounts and temperatures. Sunshine is abundant, with the infrequent cloudy weather occurring mostly during the winter and early spring months.
The average rainfall is 17.61 inches, but this value may be misleading because of the large differences from one year to the next. Extremely dry years were 1934, 1946, 1951, 1952, 1953, and 1965 and 1998 (10.12), with less than 10 inches. Only 7.06 inches fell in 1956. The wettest year on record was 1941 with 39.07 inches (233% of normal). More than 27 inches fell in 1932, 1935, and 1986. Seventy-five percent of the average annual rainfall occurs during the warmer half of the year, May through October. Most of this warm season rainfall is the result of thunderstorm activity, which helps to account for the extreme variability in amounts from year to year, and from one location to another.
Snow falls occasionally during the winter months, but is generally light, and remains on the ground only a short time. Infrequently, deep low pressure centers will develop over the South Plains during late January or February that will produce heavy snows in the region, but these excessive amounts are rare.
Temperatures, like rainfall, vary over a wide range. Winters are characterized by frequent cold periods followed by rapid warming. This produces frequent and pronounced temperature changes. Summers are hot and usually dry except for small thundershowers. Low humidity and adequate wind circulation, resulting in rapid evaporation help to moderate the effect of the heat. Evaporative coolers are quite efficient in the area.
The prevailing wind is from the south from about May through October, and from the southwest, November through April. The strongest winds occur during the severe thunderstorms of late spring and early summer, but these are gusts or squalls of short duration. The strongest continuous winds occur during March and April as a result of intense low pressure centers that originate on the High Plains region just to the east of the Rocky Mountains. These winds often produce severe dust storms in the region during drought years.
Humidity is rather low, with the highest values occurring during the early morning hours, and the lowest during the afternoons. Early morning values may be expected to average about 75 percent, while afternoon values will average between 40 and 45 percent. As would be expected, evaporation is high in this semi-arid region. Average annual lake evaporation is estimated at 72 inches per year.
Hail may accompany thunderstorms anytime they occur; however, the most damaging hailstorms are usually associated with the severe thunderstorms of the late spring or early summer.
The growing season is short when compared to Central or South Texas, but sufficiently long for cotton. The average freeze free period [the number of days between the last occurrence of 32 degrees F in the spring (April 2) and the first occurrence of 32 degrees in the fall (Nov. 4)] is approximately 216 days.
Lamesa’s Freeze Dates for the Past 53 Years
Last Freeze First Freeze Length of
Year in Spring in the Fall Growing Season
1949 April 5 October 31 209 days
1950 April 6 November 4 212 days
1951 April 14 November 2 202 days
1952 April 11 November 10 213 days
1953 Missing November 9
1954 April 2 October 31 212 days
1955 March 29 October 25 210 days
1956 April 11 November 5 208 days
1957 April 14 October 27 196 days
1958 March 20 November 1 226 days
1959 April 15 October 28 196 days
1960 April 4 October 31 210 days
1961 April 17 November 3 200 days
1962 April 2 Missing
1963 March 20 November 23 248 days
1964 April 10 November 20 224 days
1965 March 27 November 27 245 days
1966 March 25 November 2 222 days
1967 March 16 November 4 243 days
1968 April 4 November 11 221 days
1969 March 27 October 31 200 days
1970 April 3 October 10 190 days
1971 April 7 November 18 225 days
1972 March 31 October 31 214 days
1973 April 11 November 22 225 days
1974 April 5 November 25 234 days
1975 April 4 November 13 223 days
1976 March 31 October 9 192 days
1977 April 5 November 2 211 days
1978 April 11 November 7 210 days
1979 April 4 November 1 211 days
1980 April 14 October 29 198 days
1981 March 23 November 10 233 days
1982 March 8 November 4 242 days
1983 April 8 November 28 234 days
1984 April 5 November 27 235 days
1985 March 5 November 20 258 days
1986 March 22 November 11 222 days
1987 April 3 November 10 221 days
1988 March 20 November 16 241 days
1989 April 11 October 19 192 days
1990 March 26 October 22 211 days
1991 April 1 October 30 213 days
1992 April 4 October 8 188 days
1993 April 9 October 30 204 days
1994 April 12 November 16 218 days
1995 April 24 November 3 192 days
1996 April 6 October 22 199 days
1997 April 15 October 27 197 days
1998 March 21 November 11 236 days
1999 April 17 November 3 201 days
2000 April 5 November 7 207 days
2001 March 28 October 16 202 days
Average April 2 November 4 216 days
Cotton Crop Heat Unit Calendar for Dawson County - 2001
Comparison of the Long Term Average Heat Unit Accumulation
with the
2001 Monthly Heat Unit (DD60) Accumulations at Lamesa, Texas
|
Time Period |
May |
June |
July |
August |
Sept. |
Oct. |
|
1932-01 Long Term Average/Month |
335 |
552 |
639 |
601 |
383 |
92A/ |
|
1932-01 Long Term Accumulation |
335 |
887 |
1,526 |
2,127 |
2,510 |
2602A/ |
|
1932-85 Long Term Average/Month |
327 |
558 |
642 |
611 |
390 |
84 |
|
1932-85 Long Term Accumulation |
327 |
885 |
1,527 |
2,138 |
2,528 |
2,612 |
|
1986-01 Long Term Average/Month |
364 |
533 |
631 |
571 |
362 |
128B/ |
|
1986-01 Long Term Accumulation |
364 |
897 |
1,528 |
2,099 |
2,461 |
2,589B/ |
|
2001 Average/Month
1997 From May 1 |
378
242 |
631
664 |
739
1,294 |
618
1,878 |
393
2,297 |
121
2,452 |
|
2001 Month Accumulation |
378 |
1,009 |
1,748 |
2,366 |
2,759 |
2,880 |
|
2001 from May 10 |
300 |
931 |
1,670 |
2,288 |
2,681 |
2,802 |
|
2001 From June 1 |
|
631 |
1,370 |
1,988 |
2,381 |
2,502 |
A/ 68 Year Average B/ 14 Year Average Prepared by John Farris, CEA-AG
Cotton Heat Unit Requirement
|
Growth Stage |
Accumulated (Test Unit) |
Growth Stage |
Accumulated (Test Unit) |
|
Planting |
0 |
First Mature Boll |
1800 |
|
Emergence |
75 |
First Open Boll |
1900 |
|
First Square |
450 |
5 Percent Mature Bolls |
1975 |
|
First Bloom |
900 |
95 Percent Mature Bolls |
2270 |
2001 Weather Data*
Average Temperature by Months 1997 through 2001
|
Temp |
1997 |
1998 |
1999 |
2000 |
2001 |
Temp |
1997 |
1998 |
1999 |
2000 |
2001 |
|
Jan. |
38.11 |
44.77 |
43.85 |
44.73 |
38.61 |
July |
80.18 |
83.93 |
76.67 |
81.44 |
83.82 |
|
Feb. |
41.00 |
43.85 |
48.40 |
47.48 |
40.68 |
Aug. |
78.85 |
78.85 |
81.40 |
79.95 |
79.92 |
|
Mar. |
53.70 |
50.15 |
52.30 |
55.21 |
47.66 |
Sept. |
73.90 |
76.95 |
71.85 |
71.74 |
70.74 |
|
Apr. |
55.60 |
58.6 |
60.65 |
60.77 |
61.5 |
Oct. |
61.55 |
65.75 |
61.35 |
61.4 |
62.24 |
|
May |
67.30 |
74.5 |
68.55 |
75.0 |
72.1 |
Nov. |
48.00 |