The month of September 2007 was warmer and drier than normal. This continued the trend which began in mid-July of much below normal rainfall and warm temperatures. That was in sharp contrast to the mid-Spring through early-July, when below normal temperatures and very heavy rains occurred in the area. Upper air high pressure was over the area for much of the month. Though this ridge occasionally weakened and permitted cool fronts into the region, Gulf moisture was limited and rainfall amounts were not heavy and were spotty.
September 2007 was 2.3 deg. Warmer than September 2006, and 0.40 inch drier. Year-to-date rainfall is 26.54 inches greater in 2007 than was the case in the drought year of 2006. The thirty-day outlook for September 2007 had called for near normal temperatures and above normal precipitation.
The week August 26-September 1 saw near normal temperatures and near normal rainfall. An upper air storm was over the region from the 28th through the 31st, with mainly afternoon showers and thunderstorms widespread on each of those days. This lowered temperatures, and brought the rainfall. There were reports of up to 3 inches of rain north of Tyler on the evening of the 29th. A cold front entered the region on the 31st, ending the showers and significantly lowering relative humidities on the 1st. The week's average temperature was 82.7, and rainfall was 0.53 inch. The week was 1.5 deg. Cooler than the previous week. Compared with the same week in 2006, the week was 1.7 deg. Warmer and 0.20 inch wetter.
The week September 2-8 saw temperatures about 2 degrees above normal, and rainfall about 75 percent of normal. Tropical Maritime air was over the region for the week, resulting in humid conditions and warm nighttime temperatures. A crossing disturbance on the 5th brought the week's only rain. The week's average temperature was 81.6 deg., which was 1.1 deg. Cooler than the previous week. Rainfall was 0.54 inch. Compared with the same week in 2006, the week was 4.9 deg. Warmer and 0.39 inch wetter.
The week September 9-15 saw near normal temperatures and no rainfall. Hurricane Humberto, which developed rapidly on the 13th, brought showers to the extreme southeast on the 13th, and otherwise kept skies cloudy and lowered daytime temperatures over the remainder of the region. A cold front crossed the region on the 14th, which kept temperatures slightly below normal and significantly lowered relative humidities. The first of the week saw a cold front entering the region on the 10th, preceded by warm and humid conditions under the Tropical Maritime air mas s of the previous week. The week's average temperature was 78.2 deg., which was 3.4 deg. Lower than the previous week. Compared with the same week in 2006, the week was 1.3 deg. Cooler, and 0.23 inch drier.
The week September 16-22 saw near normal temperatures and no precipitation. For most of the week, dry air was over the region, resulting in mild nighttime and warm daytime temperatures. Moist air returned briefly on the 19th, but was replaced by another cold front and dry air on the 20th. The week's average temperature was 77.5 deg., which was 0.7 deg. Cooler than the previous week. Compared with the same week in 2006, the week was also 0.7 deg. Cooler, and 0.53 inch drier.
The week September 23-29 saw temperatures about 4 degrees above normal, and no rainfall. Tropical Maritime air was in and out of the region during the week, with a cold front on the 27th finally scouring out the humid air. There were scattered showes and thunderstorms in the region daily from the 24th through 27th, though rain did not fall in Tyler. Otherwise, upper air high pressure was in control, resulting in daytime high readings several degrees above normal. The week's average temperature was 79.2 deg., which was 1.7 deg. Warmer than the previous week. Compared with the same week in 2006, the week was 7.3 deg. Warmer, and 0.03 inch drier. Moist air returned on the 30th, with a few isolated afternoon showers.
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.
MX MN OBS PCPN REMARKS
September 2007, RECORDS AND SUMMARY: