September 2011

Report and Summary

Tyler, Texas
September 2011
by Robert K. Peters, Ph.D.
National Weather Service Cooperating Observer

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.

• KEY TO SYMBOLS:
• A = HAIL
• B = BLOWING
• D = DUST
• F = FOG
• H = HAZE
• IP = SLEET
• K = SMOKE
• L = DRIZZLE
• R = RAIN
• S = SNOW
• T = THUNDERSTORM
• Z = GREENWICH MEAN TIME
• ZL = FREEZING DRIZZLE
• ZR = FREEZING RAIN
• - = LIGHT
• + = HEAVY

R FOLLOWING A TEMPERATURE OR PRECIPITATION VALUE = RECORD;

The reporting period for temperatures, precipitation, 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. 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.

September 2011

• 01 101 73 97
• 02 99 78 94
• 03 94 72 85
• 04 92 74 89
• 05 86 69 84
• 06 89 6083 K
• 07 89 55 84 K
• 08 90 64 84 K
• 09 90 57 84
• 10 94 56 87
• 11 98 65 91
• 12 102 64 94
• 13 106 70 99
• 14 98 76 92
• 15 82 66 75
• 16 90 65 87
• 17 94 70 88
• 18 93 74 87 0.01 PCPN 1500-1600
• 19 87 65 81 0.97 T, PCPN 0300-0800 MX 1200-2400 86
• 20 90 66 83
• 21 91 66 86
• 22 89 65 78 tr. T
• 23 82 61 77
• 24 92 55 84
• 25 99 72 93
• 26 93 65 87
• 27 95 67 88
• 28 95 70 86
• 29 97 66 90
• 30 84 70 81

September 2011, RECORDS AND SUMMARY:

• 2ND EQUALED RECORD HIGH MINIMUM 78, FIRST SET IN 1989;
• 6TH SMOKE WITH VSBY 2MI FROM AREA WILD FIRES 15Z-20Z
• 7TH RECORD LOW MINIMUM 55, PREVIOUS RECORD 58 IN 1950 AND 1968;
• 7TH SMOKE FROM WILD FIRES;
• 8TH, SMOKE FROM WILD FIRES;
• 12TH RECORD HIGH MAXIMUM 102, PREVIOUS RECORD 100 IN 1920, 1939,
• AND 1982;
• 13TH RECORD HIGH MAXIMUM 106, PREVIOUS RECORD 101 IN 1939,
• WARMEST FOR SO LATE IN THE SEASON;
• 23RD ASTRONOMICAL ONSET OF AUTUMN 0905Z;
• 25TH RECORD HIGH MAXIMUM 99, PREVIOUS RECORD 98 IN 1939;
• 29TH RECORD HIGH MAXIMUM 97, PREVIOUS RECORD 96 IN 1954;
• HIGHEST TEMPERATURE 106 ON THE 13TH,
• LOWEST TEMPERATURE 55 ON THE 7TH AND 24TH,
• AVERAGE MAXIMUM 92.9 F.,
• AVERAGE MINIMUM 66.5 F.,
• AVERAGE TEMPERATURE 79.9 F.,
• 3.6 DEG. WARMER THAN NORMAL.
• 0 HEATING DEGREE DAYS,
• 0 PERCENT OF NORMAL HEATING DEGREE DAYS.
• 445 COOLING DEGREE DAYS,
• 131.3 PERCENT OF NORMAL COOLING DEGREE-DAYS;
• TOTAL PRECIPITATION 0.98 IN.,
• 2.07 IN. LESS THAN MONTHLY NORMAL.
• 32.1 PERCENT OF NORMAL MONTHLY PRECIPITATION.
• YEAR-TO-DATE PRECIPITATION 17.38 IN.,
• 15.48 IN. LESS THAN NORMAL YEAR-TO-DATE PRECIPITATION,
• 52.9 PERCENT OF NORMAL YEAR-TO-DATE PRECIPITATION;
• 2 DAYS ON WHICH THUNDERSTORMS OCCURRED;
• 2 DAYS ON WHICH MEASURABLE PRECIPITATION OCCURRED;
• 2 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO BETWEEN « AND 6 MILES BY FOG, SMOKE, OR HAZE;
• 0 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO 1/4 MILE OR LESS BY FOG;
• 0 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED BY DUST OR BLOWING DUST;
• 0 DAYS ON WHICH FROZEN PRECIPITATION WAS OBSERVED;
• 0 IN. TOTAL SNOWFALL.
• 22 DAYS ON WHICH THE MAXIMUM TEMPERATURE REACHED OR EXCEEDED 90 DEG.;
• 3 DAYS ON WHICH THE MAXIMUM TEMPERATURE REACHED OR EXCEEDED 100 DEG.;
• 0 DAYS ON WHICH THE TEMPERATURE FAILED TO RISE ABOVE 32 DEG.
• 0 DAYS ON WHICH THE MINIMUM TEMPERATURE REACHED OR FELL BELOW 32 DEG.
• 0 SEASON-TO-DATE HEATING DEGREE DAYS,
• PERCENTAGE OF NORMAL SEASON-TO-DATE HEATING DEGREE DAYS: 0;
• 3044 YEAR-TO-DATE COOLING DEGREE DAYS.
• PERCENTAGE OF NORMAL YEAR-TO-DATE COOLING DEGREE DAYS: 136.9.
• PRECIPITATION DURING THE PREVIOUS TWELVE MONTHS 23.14 IN.,
• TWELVE-MONTH PRECIPITATION PERCENTAGE 49.6.

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