August 8th Upper Level Atmospheric flow pattern (click to enlarge)
Observed flow pattern at 500 millibars (approximately 18,000 to 20,000 feet above ground) across North America, August 8th.
August 18th forecast of the Upper Level Atmospheric flow pattern (click to enlarge)
Forecast flow pattern at 500 millibars across North America, for August 18th. Little change in the pattern is expected, keeping hot and rain free weather across much of Texas.
Memories of 2009
August 2011 Heat, Wind, and Building Drought Match Closely

Overview
After a July that was bookended by locally heavy rainfall on the 1st and 2nd, and finished with a dissipating "Don", August returned the Rio Grande Valley, Rio Grande Plains, and Brush Country to the hot, dusty weather that was common through May and much of June. Through August 8th, Conditions were familiar to those who were in Deep South Texas in 2009: 100°F daytime temperatures, "Feels like" temperatures near 110°F each afternoon in the Lower Valley, gusty southeast winds to 30 mph at times, and an increased threat for rapid wild fire growth as drought conditions worsened. How does the remainder of August look? Almost identical to 2009. Rain arrived on the final day of that month; forecast data (above) suggest no rain until further notice, taking us deep into August and perhaps through the first weeks of the 2011/2012 school year. The usual safety guidelines apply as the region swelters on:

  • Stay Cool! Practice heat safety, including:
    • Drinking plenty of water, even if not thirsty
    • Taking frequent breaks in shady spots if working outdoors
    • Reserving strenuous exercise for the early morning hours
    • Staying in air conditioned buildings if sensitive to the heat.
    • Wearing sunscreen and a hat to protect from extreme ultraviolet rays
    • Wearing light weight, loose fitting clothing
    • Beat the Heat, Check the Backseat! | En Español
    • Football Coaches are strongly urged to follow the most recent guidelines from the American Academy of Pediatrics on heat stress and children/adolescent exercise.
    • More information at the NOAA/NWS Heat Safety Website.

  • Be Firewise! Dry grasses and brush continue to be a threat for rapid wildfire growth. Most recently, sparks from a hot vehicle triggered a fire which rapidly spread to 1,000 acres in northwest Hidalgo County on August 3rd. The best fire is the one that never starts. While the severe to exceptional drought continues, be sure to:
    • Refrain from using welding or grinding equipment in tall grass.
    • Park vehicles on pavement or dirt, away from any tall grass. Avoid driving farm vehicles into tall grass or brush during the hottest and breeziest times of day
    • Extinguish cigarettes and other lighted objects into ashtrays or other safe receptacles.
    • Burn bans remain in effect for most counties in the Rio Grande Valley. Violating the ban is a criminal offense and could result in jail time.
    • More information at Firewise.org.

  • Conserve. While only a few communities have instituted occasional water restrictions, it is becoming imperative that residents do what they can to conserve water. At Falcon International Reservoir, water levels had dropped to 54 percent of capacity. Should the typical rains of September fail to materialize, the potential exists for a continuing and perhaps intensifying drought as the Valley heads toward its usual dry season during autumn. Such a situation would require water restrictions to begin or spread across the Valley. Much of Texas already has water restrictions in place. In general, these restrictions include residential property irrigation (watering) and vehicle washes. If irrigating, do so during the early morning (4 AM to 7 AM), limit to three times a week, and limit station times. When washing vehicles, do so infrequently, use a automatic shutoff nozzle, and consider reducing runoff by watering over grass rather than pavement.

The following tables show where conditions stand in terms of heat and drought. Table 1 compares August 2011 (through the 8th) with August, 2009 (entire month); should current trends continue through the rest of the month, the 2009 levels may be met or exceeded. Table 2 updates the water year rains and deficits shown in the June summary, as of August 8th, 2011.

Table 1: Average Temperatures, August 1-8, 2011, vs. August (all), 2009
Station
Aug 1-8, 2011
Rank
August 2009
Rank
Brownsville (since 1871)
87.3
1
86.2
11
Weslaco (since 1928¹)
88.3
1
88.1
2
Falcon Dam (since 1962)
92.8
1
89.4
4
La Joya/Mission (since 1911)
90.9
1
89.1
3
San Manuel (since 2000)
89.1
1
86.6
2
Santa Rosa (since 1987)
88.3*
1
87.8
3
McAllen/Miller Arpt. (since 1961)
90.4
2
91.4
1
Port Mansfield (since 1958¹)
86.2
2
85.3
3
Port Isabel (since 1928¹)
86.9
2
86.0
4
Harlingen/Coop (since 1911)
87.9
2
87.2
8
Raymondville (since 1913¹)
88.1
2
86.7
11
McCook (since 1941)
88.8*
3
89.1
2
Rio Grande City (since 1900¹)
90.1
4
89.2
10
Sarita
87.5
n/a
86.3
n/a
Mercedes
87.3
n/a
86.5
n/a
*Missing 3 of 8 days.


Current Water Year Rainfall (October 1, 2010 to August 8th, 2011) Compared with Prior Records
Location
Current Rainfall
(Dry Rank)
Prior Record (year)
Rain Needed to Reach Average (in.)
Falcon Dam
2.89 (1)
n/a
11.49
La Joya/Mission
3.98 (1)
n/a
11.52
Hebbronville
6.03 (1)*
n/a
10.80
Mc Cook
3.87 (1)*
n/a
12.71
Port Mansfield
6.43 (3)
3.18 (2008/09)
12.70
Rio Grande City
4.81 (3)
3.76 (1901/02)
9.37
McAllen/Miller Arpt
7.36 (5)
6.62 (1968/69)
8.96
Raymondville
9.00 (8)
7.34 (2008/09)
10.71
Harlingen/Coop
12.13 (10)
7.46 (1952/53)
6.27
Mercedes 6 SSE
10.25 (10)
5.22 (1955/56)
8.07
Sarita
10.84 (12)
4.00 (2008/09)
9.55
Brownsville
12.36 (18)
6.44 (1952/53)
6.23
*Missing ≥28 days
Departure from average rainfall, Deep South Texas, October 1 through August 8th 2011 (click to enlarge)
Above: Water year departures as of August 8th 2011 (since October 1, 2010) from average rainfall for Deep South Texas.

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.