July 25, 2008
The remnants of Hurricane Dolly have provided a mixed bag of damaging floods and welcome drought relief for residents of south Texas.
The state’s Lower Rio Grande Valley received the storm system’s highest concentrations with isolated areas receiving as much as a foot of rainfall. Estimated rainfall between five and 12 inches in Cameron County caused widespread flooding of poor drainage areas from Brownsville to Port Isabel and South Padre Island. Numerous roads were covered in water and some locations were impassible.
However, that was not the region in need of relief. Recent heavy rains had already taken the southernmost counties of Cameron, Willacy and Hidalgo from abnormally dry and moderate to non-drought conditions. An influx of tropical moisture during the first week of July ended the drought in the lower Rio Grande Valley.
Much of south Texas stood to benefit when Dolly moved inland. The most recent U.S. Drought Monitor indicated portions of south Texas within an area from Corpus Christi to Galveston to Austin/San Antonio and west to Laredo were in extreme drought — with a core area of exceptional drought along Interstate 10 from the San Antonio area to just west of Houston.
Core rainfall amounts of at least two to five inches associated with Hurricane Dolly fell across portions of Texas south of a line from Laredo to Corpus Christi, essentially ending drought conditions in this area. As an example, Corpus Christi received only 7.83 inches of precipitation during the first six months of the year — but added another 5.47 inches during two days of Dolly.
Dolly’s outer rain bands also brought needed precipitation to parts of south Texas — east of Interstate 35 and south of Interstate 10. Portions of this area received amounts of one-half to five inches, improving conditions to the remainder of drought stricken south Texas.
Rainfall amounts to the north, including the San Antonio and Austin area, were far too light to make much of a dent in the drought, year-to-date totals in San Antonio are still around a foot below normal. Austin has measured less than one-half inch so far this month.
Some rainfall amounts over the two days within the area of extreme to exceptional drought include:
Houston Hobby Airport 2.02”
San Antonio 1.03”
A complete drought assessment for Texas and the nation may be found on the U.S. Drought Monitor, which is updated every Thursday. .NOAA understands and predicts changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.