September 2012 Weather Highlights for West-Central Texas

...5th Wettest September at Abilene... 
...8th Wettest September at San Angelo... 

Precipitation for September was largely influenced by the significant heavy rain 
event late in the month. The monthly rainfall amounts were in the 5-10 inch range 
across a large area extending from the southern Big Country south-southwest across 
the Concho Valley and Coleman County, and into Crockett and northwestern Schleicher 
Counties. The highest monthly totals, in the 10-15 inch range, occurred in a few 
pockets of Runnels, Concho, Coleman and Callahan Counties. These monthly amounts 
were much above normal, and occurred in one of the climatologically wetter months of 
the year. 

Not all of west-central Texas received above normal monthly rainfall, however. 
September rainfall was below normal in parts of the northern Big Country, Northern 
Edwards Plateau, Northwest Hill Country and Heartland, where the monthly amounts 
were in the range of 1-3 inches. 

Temperatures averaged above normal for the month. 

At Abilene Regional Airport, the average temperature for September was 77.4 degrees. 
This was 1.9 degrees above the normal average temperature of 75.5 degrees. Total 
precipitation for Abilene in September was 8.48 inches. This was 6.24 inches above 
the normal of 2.24 inches. This marks the 5th wettest September on record at 
Abilene. 

At San Angelo Regional Airport, the average temperature for September was 78.5 
degrees. This was 2.9 degrees above the normal average temperature of 75.6 degrees. 
Total precipitation for San Angelo was 6.91 inches. This was 4.45 inches above the 
normal of 2.46 inches. This marks the 8th wettest September on record at San 
Angelo. 

The number of days in September with high temperatures of 100 degrees or more 
include: 7 at San Angelo, and 6 at Abilene, and 6 at Junction. 

September 2012 Weather Highlights... 

Hot and dry conditions occurred during the first week of September, as an upper 
level high pressure system became established over west and northwest Texas. 
Temperatures were well-above normal, and several records were tied or broken. 

Across west-central Texas, afternoon highs were mostly in the range of the upper 90s 
to 105 degrees. 

At San Angelo, the low temperature of 79 degrees on the 1st not only set a new 
record high minimum temperature for that date, but also tied the record high minimum 
for the month of September. In addition, record high minimum temperatures were set 
on the 5th and tied on the 3rd. Record high temperatures were set in San Angelo on 
the 6th and 7th. 

At Abilene, the low temperature of 80 degrees on the 5th not only set a new record 
high minimum temperature for that date, but also set a new record high minimum for 
the month of September. This marked the first time in September in which a low 
temperature of 80 degrees (or more) was recorded in Abilene. In addition, a record 
high minimum temperature was set on the 4th, and a record high temperature was set 
on the 7th. 

A change to cooler temperatures occurred when a strong cold front (for early 
September) pushed south across the region during the overnight hours of the 7th and 
8th. Gusty north-northeast winds followed passage of the cold front. Peak wind 
gusts of 45 mph were recorded at Abilene, with 43 mph recorded at San Angelo. After 
the frontal passage, a few showers occurred across the Big Country. Rainfall 
amounts were mostly less than one tenth of an inch. With the influx of cooler air 
and presence of cloud cover, temperatures were confined generally to the upper 70s 
to mid 80s for highs on the 8th. These readings were 15-25 degrees cooler than what 
occurred on the 7th. 

As high pressure settled into west-central Texas from the north, a combination of 
partially clearing skies, dry air and light winds allowed temperatures to drop into 
the 50s for early morning lows on the 9th. Lows were in the 60-65 degree range 
Where cloud cover remained. Lows on the 10th were in the 50s to lower 60s. 

A warming trend occurred on the 10th-12th, as an upper level high pressure system 
expanded east over the southern states. Afternoon highs were in the 90s during this 
time. 

A significant change to cooler and wetter conditions occurred on the 13th-16th. A 
strong cold front moved south across west-central Texas on the 13th. Showers and 
thunderstorms occurred in association with the approaching cold front and an upper 
level disturbance. The coverage of showers and storms was widespread, and rainfall 
was locally heavy. The highest rainfall amounts (3-5 inches) occurred in parts of 
Haskell, Throckmorton, Irion, and Coleman Counties. Rainfall amounts of 1 to 3 
inches occurred at widely scattered locations. Numerous locations received amounts 
ranging from one half to one inch. Temperatures were much cooler behind the cold 
front on the 13th. 

Cool air remained over the region on the 14th, with widespread cloud cover. Daytime 
temperatures were confined to the 60s for highs across most of west-central Texas. 

With the gradual approach of a weak upper level low pressure system from New Mexico, 
considerable cloud cover lingered over west-central Texas on the 15th. Rain showers 
overspread much of west-central Texas on the late afternoon and evening hours of the 
15th. The showers lingered into the overnight hours across southeastern sections of 
the region, where amounts of one half to one inch occurred. 

Gradual clearing occurred from the west on the 16th, as the upper level system moved 
slowly east across the region. With clear skies and light winds, patchy fog 
developed during the post-Midnight and early morning hours of the 17th. Visibility 
dropped to less than 1 mile at some locations across the Heartland and Northwest 
Hill Country. 

A few strong to severe thunderstorms occurred during the early morning of the 18th, 
as a strong upper level disturbance and cold front moved south-southeast into west- 
central Texas. Wind damage was caused by a thunderstorm downburst in Rotan (Fisher 
County). Numerous tree limbs and a few trees were blown down, and several large 
storage tanks were knocked over. In addition, the strong winds caused minor 
structural damage to a few metal roofs. Nickel size hail was reported in Rotan, and 
3 miles southeast of Roby. 

The coverage of showers and storms on the 18th was fairly widespread across the Big 
Country, and scattered farther south across the rest of west-central Texas. 
Rainfall amounts of one half to one inch occurred across much of the northwestern 
Big Country, and at scattered locations farther to the south. A few locations in 
the northern and eastern Concho Valley received more than one inch of rainfall. 

After the cold frontal passage, a high pressure system settled south into west- 
central Texas on the night of the 18th. This provided a setup with clear skies, 
light winds and drier air, which resulted in cool low temperatures (in the 50s) on 
the early morning of the 19th. 

Warm and dry conditions occurred on the 20th-24th, as an upper level high pressure 
system gradually shifted to the southeast, from the western states into Texas. 
Afternoon highs were several degrees above normal (mostly in the 90-95 degree range) 
during this time. The warm temperatures continued on the 25th and 26th, along with 
more humid conditions, as moisture gradually increased across the region. 

A significant and widespread heavy rainfall event occurred on the 27th-29th. A 
number of favorable weather ingredients came together for this event. A surge of 
low-level moisture into the region from the Gulf of Mexico was combined with middle 
to upper level moisture, which emanated from the eastern Pacific and a couple of 
tropical cyclones west of the Baja Peninsula. This effectively created a very moist 
airmass. Several upper level disturbances entered the region from Mexico during 
this time and generated large areas of rain showers with moderate to heavy rainfall. 
This resulted in a long duration of rainfall for much of west-central Texas. The 
longest duration and highest amount of rainfall occurred across the region south of 
a Roby to Albany line and north of an Ozona to Richland Springs line. 

Total rainfall across much of this area varied from 4 to 8 inches, with isolated 
totals between 8 and 11 inches. At the San Angelo Regional Airport, a total of 5.84 
inches was recorded. In other parts of San Angelo, rainfall totals between 6 and 
7.5 inches were measured. Abilene recorded a total of 7.08 inches. New daily 
rainfall records were set at San Angelo on the 28th and 29th, and at Abilene on the 
29th. 

The rainfall caused considerable street flooding in the San Angelo and Abilene 
areas, where barricades were placed on some of the roads. A number of other roads 
across the Concho Valley and Big Country were also closed temporarily, due to 
flooding. Most of the short-term flooding occurred on the 28th and 29th. 

The rainfall also led to substantial runoff into area rivers, streams, and 
reservoirs. Flooding occurred along the Colorado River in parts of Coke and Runnels 
Counties. Flooding also occurred along the Concho River at Paint Rock (Concho 
County). The most substantial flooding occurred near the confluence of Elm Creek 
and the Colorado River, on the southeast side of Ballinger. This prompted 
precautionary evacuation of the surrounding homes in that area. 

Water levels increased on the area reservoirs, most notably at Lake O.H. Ivie. 
The list of other reservoirs with water increases include: Twin Buttes, O.C. 
Fisher, Lake E.V. Spence, Lake Nasworthy, Brady Creek, Fort Phantom Hill, Lake 
Abilene, Lake Brownwood, Lake Coleman, and Hords Creek. Minor increases occurred at 
Lake Stamford and Lake Sweetwater. 

This rainfall and runoff event helped to alleviate ongoing drought conditions across 
the Concho Valley, Heartland, and southern part of the Big Country. Drought 
conditions were alleviated to a lesser extent across the northern Big Country and in 
southern parts of west-central Texas.