The mohth of May 2001 was somewhat warmer and somewhat drier than normal. Compared with May 2000, last month was 1.6 deg. cooler, and 6.92 inches drier. Year-to-date rainfall through May 31, 2001 was 29.01 inches. This was 2.50 inches wetter than through the same period last year. Rainfall during the twelve months ending May 31, 2001 is 131.6 percent of normal. The thirty-day outlook for May 2001 had called for above normal temperatures and below normal precipitation.
The week April 29-May 5, 2001 saw temperatures two degrees warmer than normal and rainfall about one-half normal. Modified Polar Continental air remained over the area from the previous week on the 29th and 30th, with Tropical Maritime air returning on the 1st. This caused nighttime temperatures to rise, though daytime temperatures held in the lower 80s. An upper air low began developing over the Southwestern United States on the 2nd. Energy from this feature caused the week's only rainfall, on the 4th and 5th.
The week May 6-12, 2001 saw temperatures two degrees warmer than normal and rainfall 250 percent of normal. The rain reported on the 6th (which actually fell the 5th) brought the bulk of the rain. In fact, it established a new May 6th rainfall record. As this upper air storm departed, upper air high pressure settled in. This brought tranquil weather and the slightly above normal temperatures. Late in the week, a much weaker upper air storm crossed with its associated cold front. This brought rain on the 12th, with amounts varying from little to none over the southern counties to more than one inch over the northeast. There were widely scattered afternoon showers over the southern counties on the afternoons of the 7th, 8th, 9th, and 10th. These resulted from sea-breeze fronts and daytime heating. The weak cold front which followed the storm of the 4th-5th finally made it through the area on the 7th. It had little effect on temperatures. The storm of the 12th also pulled another weak cold front through. this brought drier air and slightly lower afternoon temperatures on the 12th.
The week May 13-19 saw temperatures four degrees warmer than normal and rainfall about one-eighth normal. High pressure aloft was in control of the area's weather through the week. This caused the very warm temperatures, and largely suppressed rainfall. The rain recorded on the 13th actually fell on the 12th. There were widely scattered showers on the afternoons of the 13th and 14th along a decaying cold front. Another weak front reached Red River on the 18th. It brought scattered showers on the night of the 18th to the extreme northeast. Tyler--Pounds Field Airport measured a trace of rain on the evening of the 18th.
The week May 20-26 saw temperatures two degrees cooler than normal and rainfall of but 0.02 inch. Cold fronts on the 21st and 24th held down temperatures. The presence of a capping inversion prevented rainfall. There were scattered showers on the morning of the 26th, which had developed earlier over Central Texas and moved into the region. The morning of the 22nd saw a record low temperature set for that date.
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 2001, RECORDS AND SUMMARY: