First, the Rain... ...Now, the Heat!
Radar depiction of storm total rainfall, May 5th (click to enlarge)
Rainfall estimate, upper portion of the Lower Rio Grande Valley, May 5th. Note: Hail contamination inflated some values.
First spring heatwave headed for parts of the Lower Rio Grande Valley, May 8-11 (click to enlarge)
Expected temperatures and heat index into Mother's Day Weekend
Early Week Relief to be followed by Searing Temperatures

After exceptional drought areas of Jim Hogg, Zapata, and Brooks Counties experienced a welcome thunderstorm complex early on May 5th, the respite will quickly evaporate under rapid heating beginning Thursday, and likely continuing into the weekend.

Helpful Rains
A small mesoscale convective system (also known as a mesoscale convective vortex) formed along the Rio Grande in the middle RGV before daybreak on May 5th, then quickly drove east across northern Zapata, Jim Hogg, and Brooks County before dissipating while moving northeast into Kleberg County by late morning. The storm, which likely contained hail as well as gusty winds, dropped an estimated 2 1/2 to 3 1/2 inches of rain near Thompsonville (in white box, above) in northwest Jim Hogg County, and left high standing water along Farm to Market Road 1017 in eastern Jim Hogg County. For many in this area, the rains were the heaviest since last year.

Into the Oven
Unfortunately, the rainfall and general cloud cover which persisted, will be a distant memory come Thursday, and likely into the weekend. The first spring heat wave will develop across all of Deep South Texas and the Lower Rio Grande Valley beginning on May 8th, and continue through at least May 10th, and probably on into Mother's Day (May 11th). From Hidalgo and Brooks County west, afternoon temperatures will easily break 100°F, and perhaps approach 110°F in areas from Rio Grande City to Hebbronville out to Zapata. While May typically features 100°F readings in these locations from time to time, this will be the first instance of prolonged hot temperatures since early March, along with a much higher sun angle. In fact, some record high temperatures will be threatened, or possibly broken, during the period.

Farther east, temperatures will be a bit lower, generally between 95 and 100 from Harlingen to Brownsville. Unfortunately, increasing surface humidity will make up the difference, and the apparent temperature will "feel like" 105 to 110°F each afternoon. Relief will be found along the immediate coast, where daytime tempeartures should hold in the 80s. This preview of summer weather provides residents of the Lower Rio Grande Valley an opportunity to review heat safety tips. These include:

  • Drinking plenty of water, even if you're not thirsty
  • Strenuous activity in the early morning or early evening
  • Wearing light weight, loose fitting clothing if you plan to be outdoors


For more information about heat and heat stress, please see the National Weather Service's Heat Safety web page for more.

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