The month of May 2005 saw near normal temperatures and below normal precipitation. Despite record high temperatures late in the month, the very cool weather of the first eight days balanced these. The rainfall deficit continued to increase. The deficit over the past twelve months is now about 15 percent, while that for Spring 2005 stood at 60.5 percent. This continues East Texas in a mild drought, which is approaching moderate drought. Precipitation accumulation and soil moisture content are used to calculate drought status on the Palmer Drought Index, which will be updated on June 1. Compared with May 2004, the month was 0.8 deg. cooler, and 2.25 inches drier. Year-to-date rainfall through May 31 was 7.16 inches less in 2005 than in 2004. The rainfall through May 31, 2005 was 6.77 inches less than normal, and the deficit was 35.3 percent. The thirty-day outlook for the month had called for near normal temperatures and near normal precipitation.
The week May 1-7 saw temperatures 7 deg. cooler than normal, and rainfall about 30 percent of normal. Polar Continental air was over the region between the 1st and 4th, with the air mass warming during the last three days of the week. The week's only rain was brought by a reinforcing cold front on the 4th. The average temperature was 64.0 deg., and precipitation was 0.28 inch. The week was 2.0 cooler than the previous week.
The week May 8-14 was in sharp contrast with the previous week, with temperatures 2 deg. warmer than normal and precipitation about 60 percent of normal. The cold front of the 7th/8th brought a brief cooling, followed by the return of Tropical Maritime air between the 9th and 14th--when another cold front arrived. Rain accompanied the cold front, with widely scattered showers and thunderstorms with another front on the 14th. The week's average temperature was 74.0 deg., which was 10.0 deg. warmer than the previous week. Precipitation totaled 0.60 inch. The week was 5.9 deg. warmer than the same week in 2004, and 0.31 inch drier.
The week May 15-21 saw temperatures about 2 deg. warmer than normal, and no rainfall. Upper air high pressure gradually shifted over the region from the southwest during the week. This caused temperatures to rise-- reaching record levels by week's end. The upper air high prevented any precipitation from occurring, as the storm track was bulged to the north of the area. The week's average temperature was 75.5. This was 1.5 deg. warmer than the previous week. Compared with the same week in 2004, the week was 1.8 deg. cooler. There was no rain during the same week last year, either.
The week May 22-28 saw temperatures about 4 deg. warmer than normal, and rainfall about 90 percent of normal. The week began with record high temperatures as the very strong upper air high pressure ridge persisted. This ridge weakened and shifted westward during the week, allowing for cooler temperatures. A weak cold front crossed on the 26th and another on the 28th with upper air support. These resulted in showers and thunderstorms, with occurrences of severe weather on both days. An estimated peak wind gust of 70 mph occurred about 10 miles south of Tyler on the afternoon of the 25th. The week's average temperature was 78.9 deg., which was 3.4 deg. warmer than the previous week. Rainfall was 0.92 inch. Compared with the same week in 2004, the week was 0.5 deg. cooler and 0.67 inch wetter.
During the final three days of the month, a crossing upper air low kept considerable cloudiness, and scattered shower and thunderstorm activity in the region. This held down temperatures, and brought light rainfall amounts.
The reporting period for temperatures and phenomenon on each day is for the twenty-four hours ending at midnight hours GMT--6 p.m. CST and 7 p.m. CDT. The reporting period for precipitation is for the twenty-four hours ending at noon GMT--6 a.m. CST and 7 a.m. CDT. All times are given using the twenty-four hour clock, and are expressed in Greenwich Mean Time.
Observations are from NWS Station 41/9207/4 in Tyler, Texas. The term "normal" refers to averages from the standard climatic period 1971-2000.
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May 2005, RECORDS AND SUMMARY: