by Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer
The month of August 2007 saw near normal temperatures and below normal rainfall.
For most of the month, upper air high pressure was in control. The heavy rainfall of earlier in the Summer kept temperatures from rising as high as was the case during the previous two Summers. Compared with August 2006, the month was 2.0 deg. Cooler and 0.52 inch drier. Year-to-date rainfall through August 31 was 26.94 inches greater in 2007 than in 2006. The thirty-day outlook for August 2007 had called for below normal temperatures and above normal precipitation.
The week July 29-August 4 saw temperatures about 2 degrees below normal, and rainfall about 275 percent of normal. Showers and thunderstorms were widespread in the area through the 2nd, when a dramatic change in the weather pattern occurred. Upper air high pressure and drier air in the lower and middle atmosphere began building into the region. This resulted in a virtual suppression of shower activity on the 3rd and 4th. Temperatures also rose. The week's average temperature was 81.5 deg., which was 3.1 deg. Warmer than the previous week. Precipitation was 1.42 inches. Compared with the same week in 2006, the week was 4.9 deg. Cooler, and there was no rain in 2006.
The week August 5-11 saw near normal temperatures and no rainfall. Upper air high pressure was in control of the weather during the week. Full sunshine permitted high levels of evaporation of soil moisture. As a result, temperatures rose slowly during the week. The upper air high also suppressed shower development. The week's average temperature was 84.3 deg. This was 2.9 deg. Warmer than the previous week. Compared with the same week in 2006, the week was 2.4 deg. Cooler and 0.01 inch drier.
The week August 12-18 saw temperatures about 2 degrees above normal, and rainfall about 40 percent of normal. Strong upper air high pressure controlled the region's weather during the first half of the week, keeping temperatures high and conditions dry. The airport reached 100 or higher between the 12th and the 15th, though the city did not. Heat advisories were required through the 15th, as afternoon heat index values approached 105. On the morning of the 16th, Tropical Storm Erin came ashore in Matagorda Bay. Its circulation moved on an arc through West Texas and into Oklahoma on the 19th. This resulted in considerable shower activity on the 16th, 17th, and 18th, and also in lower temperatures. The week's average temperature was 86.3 deg., and rainfall was 0.24 inch. The week was 2.0 deg. Warmer than the previous week. Compared with the same week in 2006, the week was 2.3 deg. Cooler, and there was no rain during the week in 2006.
The week August 19-25 saw temperatures about 1 degree above normal, and no measurable rainfall. Upper air high pressure dominated the area much of the week. High cloudiness from Hurricane Dean held down temperatures at mid-week. Though isolated heavy showers fell on the 21st and 25th, only a trace of rain fell in the city on the evening of the 21st. The week's average temperature was 84.2 deg.. The week was 2.1 deg. Cooler than the previous week. Compared with the same week in 2006, the week was 3.4 deg. Cooler, and 1.21 inches wetter.
An upper air storm system was over the region between the 28th and 31th, bringing scattered shower activity. Some of the rains on the afternoon and evening of the 29th were heavy, resulting in amounts of 1 to 3 inches north of Tyler. Measurable rain fell in the city on the 31st, and at the airport on the 28th, 29th, and 31st. Temperatures during the final six days of the month began above normal, but lowered to near normal values by the 30th because of clouds and showers and the passage of a cold front on the 30th.
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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AUGUST 2007, RECORDS AND SUMMARY: