The month of September 2011 was warmer and drier than normal. Coming off the hottest Summer and hottest August on record, September was less extreme not ranking in the five hottest Septembers.
Continuing the dry trend which commenced in the late-Spring of 2010, precipitation was less than one-third normal. Compared with September 2010, the month was 0.9 deg. Warmer, and 0.07 inch drier. Year-to-date rainfall through month's end was 12.76 inches less in 2011 than in 2010. The thirty-day outlook had called for above normal temperatures and below normal precipitation.
The month began hot, with well above normal temperatures through the 2nd. These fell beginning on the 3rd, resulting in below normal temperatures beginning with the 5th.
The cause was Tropical Storm Lee to the east of the region and upper air high pressure to the west, resulting in northwest winds aloft which permitted cool air to drop in from the north. Lee brought rainfall amounts of one-half in or less east of a Lufkin-Marshall line, and only trace amounts elsewhere.
The very dry and hot Summer combined with strong winds around the west side of Tropical Storm Lee to generate numerous fires between the 3rd and 6th. There were two fatalities in Gregg County on the 4th, and several hundred persons were evacuated, and numerous homes were destroyed.
The plumes of smoke combined with a temperature inversion on the 6th to result in dense smoke in Tyler, with the visibility dropping to 2 miles at one point. Dense smoke advisories were required through the 8th.
On the 9th, upper air high pressure returned, sending temperatures back to well above normal levels through the 14th. Record highs were set on the 12th and 13th, with the 106 on the 13th the warmest ever for so late in the season.
The 100-degree plus reading on the 13th marked the fifty- seventh time in 2011 that the mercury reached or exceeded 100 degrees a record replacing the previous record of 51 from 1954. Slightly cooler temperatures were in the area between the 15th and 22nd, with a storm system crossing on the 19th bringing rainfall.
Upper air high pressure built back into the region on the 23rd, again sending temperatures well above normal with more record high temperatures observed. A cold front arrived on the 30th, lowering temperatures.
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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September 2011, RECORDS AND SUMMARY: