The increased cloudiness and rainfall will also provide a break from the summer heat, with afternoon temps running 5 to 10 degrees below average in the 80s for the next few days.
The heat dome, produced by a strong ridge of high atmospheric pressure, has shifted north into the northern Plains. Along the southern edge of that ridge, the clockwise air circulation is steering several slow-moving upper-level atmospheric disturbances from east to west. They’re transiting across a stalled frontal boundary draped over the southern United States, including Texas.
At the same time, persistent southerly and southeasterly winds are pumping deep volumes of tropical moisture from the Gulf of Mexico into the region, providing plenty of fuel for heavy rainfall.
This weather pattern on the periphery of the high pressure is referred to as the “ring of fire.” It often produces repeated rounds of showers and thunderstorms capable of producing torrential downpours, localized flash flooding, and occasional strong wind gusts on the outer edge of the heat dome.
While we’ll see several rounds of rain and thunderstorms from Tuesday through Thursday, the timing will be intermittent.
We’ll wake up Tuesday to overcast skies with scattered showers and thunderstorms around San Antonio. By mid-morning, more storms will develop and become more widespread, bringing pockets of moderate to heavy rainfall. That activity will continue through the afternoon and into the early evening.
We may catch a brief break later Tuesday evening, but another round of showers and thunderstorms is expected to move through overnight, bringing new rounds of moderate to heavy rainfall.
“A mid-level impulse will rotate slowly around the south side of high and interact with the warm, moist air mass over South-Central Texas Tuesday night into Thursday morning,” meteorologists at the regional National Weather Service office wrote in their daily forecast discussion for South Texas. “Rainfall totals through Thursday could be 2-6 inches with isolated (amounts of) 8 inches.”
With abundant cloudiness and frequent rounds of rainfall, peak daytime temperatures will be noticeably cooler. Many areas will remain below 90 degrees from Tuesday through Thursday, with afternoon temps staying below the mid-July average of 96 degrees through the end of the week.
Because flash flooding could develop overnight while many people are asleep, it’s important to make sure Wireless Emergency Alerts are enabled on your phone. These location-based alerts can warn you about life-threatening flash floods and tornadoes — even if your phone is set to silent.