Summer heat is taking a temporary break in parts of Texas, but the tradeoff is a growing risk of heavy rain and flooding.
Scattered to numerous showers and thunderstorms were already underway Monday morning across Southeast Texas, East Texas, the Golden Triangle, the ArkLaTex, southern North Texas, and portions of the Big Country and Permian Basin.
Additional rounds of rain are expected through at least Wednesday or Thursday. This will not be a complete washout everywhere, but some communities may receive repeated storms and far too much rain.
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Moderate Flood Risk for the Edwards Plateau
The Weather Prediction Center has placed portions of the Edwards Plateau under a Level 3 of 4 Moderate Risk for excessive rainfall and rapid-onset flooding.
The greatest concern is primarily tonight into Tuesday morning, including areas near Del Rio, Eagle Pass, southwest of Kerrville, and locations west of Bexar County.
Scattered flooding is also possible across a much larger portion of Texas, including the Big Bend, Permian Basin, Concho Valley, Big Country, Hill Country, Central Texas, South-Central Texas, Brazos Valley, Southeast Texas, East Texas, and the ArkLaTex.
This Is a Multi-Day Event
This is not a one-and-done round of storms.
There will be breaks in the rain, but additional showers and thunderstorms may redevelop repeatedly through the middle of the week. Some locations could receive several rounds of heavy rain before conditions begin improving.
The greatest flooding concern remains focused on the Edwards Plateau, western Hill Country, and eastern Big Bend. By Thursday and Friday, the heavier-rain focus may gradually shift farther west toward the Permian Basin, Big Bend, and Borderland.
Slow Storms Could Produce Torrential Rain
Texas has an exceptional amount of moisture in place. Even showers without much lightning may produce two to four inches of rain in 45 to 60 minutes.
Storms will also move slowly because upper-level steering winds are weak. That increases the risk that heavy rain will remain over one community or watershed for an extended period.
The primary hazards include:
- Rapid street and low-water crossing flooding
- Quick rises on creeks and streams
- River impacts where repeated rain falls over the same basin
- Frequent cloud-to-ground lightning
- Gusty winds with stronger thunderstorms
Small circulations known as mesoscale convective vortices may also develop within larger storm clusters. If one forms, it could enhance overnight rainfall across a relatively small area.
Seven to Ten Inches Possible in Spots
Forecast rainfall totals through Saturday have increased considerably.
Parts of the Edwards Plateau and eastern Big Bend may receive seven to ten inches of rain. Four to seven inches are possible across portions of the western Hill Country.
The Austin area may average two to three inches, with localized amounts approaching six inches. Locations along the Interstate 20 corridor may generally receive one-half inch to two inches.
These totals are regional estimates—not exact neighborhood forecasts. Some places will receive much less, while isolated locations could receive considerably more if storms repeatedly develop over the same area.
Rocky Terrain Increases the Danger
The Big Bend, Edwards Plateau, and Hill Country are especially vulnerable to rapid flooding.
Rocky and limestone terrain cannot absorb rainfall as efficiently as deeper soil. Water may quickly run into roads, low-water crossings, creeks, streams, and river channels.
Rain falling upstream can also create dangerous conditions downstream, even where little or no rain is falling at that moment.
Flood Safety
Never drive through water covering a roadway. The depth and condition of the road underneath may be impossible to determine.
Campers and anyone spending time near creeks, rivers, streams, or low-water crossings should monitor both local rainfall and conditions upstream.
Keep phones charged, enable weather alerts, and have another route available if nearby roads are prone to flooding.
Cooler Temperatures, but Humidity Remains
Clouds and rain will keep afternoon temperatures below normal across parts of Texas this week.
Many locations will remain in the upper 70s and 80s, while areas with fewer storms will reach the 90s. South Texas and the Rio Grande Plains will remain the hottest portions of the state.
The cooler temperatures will be welcome, but the additional soil moisture means high humidity will remain firmly in place.
Bottom Line
Texas is entering a multi-day heavy-rain event with an increasing risk of flooding.
Not everyone will receive excessive rain, but locations affected by repeated slow-moving storms may experience flooded roads, dangerous low-water crossings, and rapid rises on creeks, streams, and rivers.
The Edwards Plateau, eastern Big Bend, western Hill Country, and nearby areas face the greatest concern through the middle of the week.
Track storms with the free Texas Storm Chasers interactive radar at TexasStormChasers.com/radar. Neighborhood forecasts, alerts, and the 24/7 live Texas radar stream are also available in the free Texas Storm Chasers mobile app.