Extreme Texas rainfall triggers flash flood emergency

As Florida battened down the hatches and withstood a strike from Tropical Storm Elsa, South Texas was enduring its own drenching deluge.

More than 10 inches of rain fell over Rockport, Texas, on Wednesday, closing in on the roughly 10 inches of rainfall Elsa dumped over a handful of Florida cities. During a 48-hour time frame, Rockport picked up more than a foot of rain.

The rain over Texas wasn't delivered by a tropical system, but by an area of low pressure over south-central Texas being cut off from the jet stream. When a system becomes cut off, this causes weather systems to move very slowly. Therefore, areas of good weather tend to last in a particular location for several days. In this case, wet weather has persisted for multiple days.

Radar estimated rainfall map for Texas over the 72-hour period prior to 10 a.m. EDT July 8, 2021.

Flash flood watches and warnings spanned across the coast of Texas over the past few days with areas like Rockport even seeing a flash flood emergency. Roads were closed throughout the Coastal Bend due to high waters, according to the Texas Department of Transportation.

One social media user posted a video of Salt Creek Wednesday near the towns of Tivoli and Refugio, Texas, and commented that the water was nearly over the bridge and moving quickly.

The city of San Antonio sent out a severe weather update Tuesday, saying the area from Leon Valley to Helotes received 6 to 7 inches of rainfall Tuesday. Coupled with the rain that fell Monday, that resulted in nearly 10 inches of rain in the area which produced widespread flooding.

Rainfall amounts in Texas were comparable or even higher than those unleashed by Elsa in Florida. Radar estimated rainfall map for Florida over the 72-hour period prior to 10 a.m. EDT July 8, 2021.

The heavy rainfall was blamed for causing portions of Leon Creek in San Antonio, Texas, to swell to near-record levels, spilling over the creek banks and driving nearby residents from their homes, KENS 5 Eyewitness reported. The city noted that five homes had been flooded, three of which required housing assistance. A mobile home experienced flooding as well, but the residents didn't request housing assistance, according to the city.

Flash flood watches and warnings (dark green and lime green, respectively), and small craft advisories (lilac) lined most of the coast of Texas on Friday, July 9, at 4 a.m. CDT.

A popular San Antonio restaurant, the Comfort Cafe, was also damaged in the flooding, leading another restaurant to lend a helping hand, according to My San Antonio.

The creek near I-35 South officially crested at 25.79 feet by Tuesday evening, the fourth highest on record, according to the National Weather Service. These floodwaters also caused a full closure of the interstate on the southwest side of San Antonio, though it has since reopened.

The flood wave from the heavy rain in Bexar County Tuesday swept downstream along the San Antonio River Wednesday, pushing river gauges at Elmendorf and Floresville to near-moderate flood stages.

While it hardly rivaled numbers from Elsa, the Victoria Airport received 2.79 inches of rainfall Wednesday, breaking the previous daily record of 1.17 inches set back in 1991. Normal rainfall for the entire month of July is 4.18 inches in Victoria. Already, 7.24 inches have fallen through just the first seven days of the month, with all of that coming since July 4.

The City of San Antonio sent out updates on severe weather updates and shelter information via Twitter. (Twitter / City of San Antonio)

Rainfall will continue into the end of the week as the cut-off system remains in place. Due to a flow off the Gulf of Mexico, the high moisture content of the air could lead to several inches of rain in a short period of time. Both the duration and intensity of the rain will heighten the flooding risk.

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In total, rainfall can reach an AccuWeather Local StormMax™ of 20 inches (510 mm) by the time the rain begins to lessen in intensity this weekend.

This amount of rain is a bit unusual for a non-tropical storm. However, even though this low pressure is not officially a tropical storm or hurricane, tropical moisture and several days of rain are leading to totals even higher than what Tropical Storm Elsa dumped on the Gulf Coast.

By the weekend, rain will largely come to an end in Texas. Thunderstorms are likely to persist in Mexico but, even there, the rain will not be as heavy as it has been recently.

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