MTW Discussion

Yesterday marks the third day in a row of an unusual streak of afternoon highs in the summer of 2009 fail to reach the triple digits. We came close as the official high at the San Antonio Airport was 99º after a morning start at 74º. July 2009 will go down in history with an average temperature of 88.8ºF.

Showers scathed the airport in San Antonio for the most part, with the exception of an early morning shower that dropped 0.03″ of rain between 3:00 and 4:00 AM. In the afternoon, a complex of thunderstorms developed along the Mexican border before fizzling out just to the west of San Antonio in Medina, Frio, and Atascosa counties. These storms released an outflow boundary which originates from downdrafts brought down from the the tops of dying thunderstorms. The outflow boundary moved northward through San Antonio around 4 and 5:00 PM dropping temperatures from the upper 90’s down to the mid 80’s. Another outflow boundary from storms over East-Central Texas moved southwestward through the Austin area; that later converged with the outflow boundary that moved through San Antonio between San Marcos and Kyle. The collision of the two boundaries ignited a couple area of thunderstorms later in the evening that moved through southern Travis County, dying out by the time it reached Downtown Austin. Additional storm development occurred in Comal and Guadalupe counties near New Braunfels, providing a lightning show for San Antonio and other surrounding communities. Since then, activity has waned tremendously and only scattered clouds remain.

There is at least one more chance for additional shower and thunderstorm development across South-Central Texas this afternoon, particularly in the Hill Country north of San Antonio. The rainfall across parts of the region the past couple days has left a slight weakness in the upper levels of the atmosphere preventing the full reinstatement of the subtropical ridge that has prevailed most of the summer. The residual energy will allow for at least a few storms to develop with peak daytime heating. Widespread severe weather is not expected, however isolated pockets strong gusty winds and small hail is possible. Most of the activity should diminish after sunset.

The question remains of whether or not we break the record for most 100º days in a year remains unanswered. Again, the record was set back in 1998 with 36 days. This year holds a very close second place spot with the present count at 35. The MyTexasWeather 8-Day Forecast predicts a high of exactly 100º today, but it will be a very close call. If storms stay far enough away from San Antonio, the record will be broken with certainty. Otherwise, the wait continues at least one more day.

Looking ahead into next week, dry and hot weather will gradually work its way back into South-Central Texas as the summertime subtropical ridge dominates the weather pattern. Expect daytime highs to hover at or above 100º with morning lows bottoming out around 80º with little to no rainfall expected through the next 8 days.

The Edwards Aquifer went up yesterday and should continue to do so as some rain did fall over the Recharge Zone on Thursday. Hopefully more rain falls again this afternoon. The Stage 3 Water Restrictions Trigger at the J-17 Well in Bexar County is 640 feet above mean sea level. San Antonio has avoided the onset of Stage 3 restrictions at least 3 times so far this summer due to last minute rains. We will continue to monitor the latest levels. Stay tuned for further developments.