Climate Summary for September 2015

Warm and dry conditions were prevalent in September.

Figure 1 shows the geographic regions across West Central Texas, which are referenced in this event summary.

Figure 1:  Geographic Regions of West-Central Texas.

Precipitation for September was well-below normal across most of west-central Texas (Figure 2).  

 Figure 2: Percent of Normal Precipitation for September, 2015.

For most of the area where the monthly precipitation was less than 25 percent of normal (red color areas), the monthly rainfall (not shown) was less than one-half inch.  Only at a few locations across Irion, northern Crockett, and Throckmorton counties was the September precipitation above normal.  The highest monthly precipitation of more than 3 inches (not shown) occurred in small parts of Irion and Crockett Counties.      

Temperatures averaged well-above normal for the month.  The daily average temperatures were above normal for the entire month at San Angelo, and for all except one day at Abilene.  Table 1 (below) summarizes September 2015 temperature, precipitation, and departure from normal for Abilene and San Angelo. 

Table 1: September Climate Data for Abilene and San Angelo.

* For San Angelo, this was the 4th warmest September on record. Abilene tied the record for the 8th warmest September. *

Dry conditions prevailed during the early part of September, with clear to partly cloudy skies and temperatures above normal.  Upper level high pressure dominated the weather pattern across west-central Texas.  On September 6-9, afternoon highs reached the 100 degree mark at some locations. 

A wildfire burned approximately 2200 acres in western Shackelford County.   

Scattered showers and thunderstorms occurred on the 9th across west-central Texas.  A weak cold front moved south into the area, eventually stalling and dissipating. On the 10th, scattered showers and thunderstorms affected mainly the southeastern part of west-central Texas.     

A stronger cold front pushed south across west-central Texas on the 11th.  Widely scattered showers and thunderstorms occurred across the Big Country, with isolated coverage elsewhere.  Quarter size hail was reported with a severe thunderstorm 3 miles east-northeast of Albany (Shackelford County).  Other storms contained gusty winds, and a 42 mph peak gust was recorded at the Abilene Regional Airport.   

Locally heavy rainfall accompanied the thunderstorms on September 9-11 (Figure 3). 

Figure 3: West-Central Texas Rainfall for the 7-day period ending at 7 AM, September 12.

The September 9-11 rainfall is encapsulated in the 7-day rainfall shown in Figure 3.  The heaviest rainfall (more than one inch) occurred in widely scattered pockets across the area.

Dry conditions with above normal temperatures occurred September 14-18, when an upper level high pressure system became re-established over Texas.  A record high temperature of 97 degrees was tied at Abilene on the 18th.  A weak cold front moved south into the area on the 19th.   

Showers and scattered thunderstorms occurred across a large part of west-central Texas on the 19th and 20th.  Rainfall was locally heavy.  Figure 4 (below) shows rainfall totals for September 19-20.

Figure 4: West-Central Texas Rainfall for the 7-day period ending at 7 AM, September 22.

Rainfall amounts of 1-2 inches, with locally higher amounts, occurred across Irion and far northern Crockett County, and in a few pockets across the Concho Valley, Throckmorton, Menard and Schleicher Counties. With increased cloud cover, temperatures were cooler with highs in the 80s across parts of west-central Texas on the 19th, and across most of the area on the 20th.

Warmer and drier conditions resumed on the 21st and continued through the 24th, when upper level high pressure shifted over Texas once again.  The upper level high pressure system retreated into the southwestern states and adjacent northern Mexico September 25-28. This allowed a weak disturbance aloft to move south into west-central Texas. With the approach and arrival of this disturbance, scattered showers and thunderstorms occurred across the western two-thirds of west-central Texas on the 26th.  A few locations received more than one inch of rainfall, while amounts of one half to one inch occurred at widely scattered locations.

Warm and dry conditions occurred at the end of the month, as the upper level high pressure system shifted east into Texas.  A couple of additional wildfires occurred, in Sutton and Coleman Counties.  The fire in Sutton County burned approximately 480 acres and occurred 15 miles east-southeast of Sonora.  The fire was fully contained on September 28.  The Coleman County fire burned approximately 336 acres and occurred 3 miles west of Echo.  This fire was fully contained on September 30.