Polo flood threat shifts toward Texas: where and when heavy rain is expected
Much of South Central Texas faces a Wednesday-to-Friday flood watch. The forecast follows flooding in New Mexico, but the heaviest rain’s location remains uncertain.
Much of South Central Texas faces a flood watch from 7 p.m. Wednesday, September 30, through 7 p.m. Friday, October 2, as moisture associated with Polo feeds approaching storms. The National Weather Service’s Wednesday morning forecast puts the main rainfall window between Wednesday night and Friday morning, with potentially dangerous flash flooding.
Widespread rainfall of 2–4 inches is forecast, with local amounts up to 8 inches. The NWS Austin/San Antonio office warns: ‘Heavy rainfall may lead to life-threatening flash flooding somewhere in the Watch area.’ Those are possible outcomes, not measurements of rain already received or a prediction that every location will flood.
Where the South Central Texas flood watch applies
The NWS forecast discussion, issued at 5:57 a.m. CDT on September 30, describes a watch covering its forecast area except portions of the Coastal Plains. It highlights the Hill Country, Edwards Plateau, Rio Grande Plains and Interstate 35 corridor as the flood risk evolves. This is a regional watch, not one covering all of Texas.
For Wednesday and Wednesday night, the discussion places the I-35 corridor and areas westward at Level 2 of 4 for flood risk. The western Hill Country, Edwards Plateau and northern Rio Grande Plains face a higher Level 3 risk.
On Thursday, the Level 3 area includes the Hill Country, I-35 corridor, southern Rio Grande Plains and eastern Edwards Plateau. These forecast risk levels are separate from the watch and warning labels used in local alerts.
When heavy rain could reach San Antonio and I-35
The main increase in storms is expected Wednesday evening and overnight into Thursday across the Rio Grande Plains and Edwards Plateau. Some forecast models develop storms farther east toward San Antonio initially, but NWS forecasters favor a start farther west.
The aviation forecast anticipates the main storm complex approaching Del Rio Wednesday evening and the I-35 corridor closer to daybreak Thursday. These are approximate windows for the approaching system, not fixed arrival times for individual neighborhoods.
The setup combines an upper-level low over southern Arizona, Polo’s remnants moving into northern Mexico and increasing moisture over South Central Texas. Forecast models show storms repeatedly developing over the same western areas overnight, raising concern about prolonged rainfall.
On Thursday, the NWS expects a northeast-to-southwest line of storms to develop and move slowly east. How quickly the approaching front moves remains a central uncertainty: heavy rain could linger over the Hill Country or I-35 corridor through Thursday afternoon and night.
What a flood watch means—and when to act
A flood watch means conditions are favorable for flooding, but flooding is not certain. A flood warning means flooding is imminent or occurring. A flash flood warning concerns rapid flooding that is imminent or already happening, according to the NWS alert definitions.
The agency says flash floods can develop within minutes to hours and can affect places where rain is not falling locally. Its guidance tells people in flood-prone areas under a flash flood warning to move immediately to higher ground.
What has already happened in New Mexico
New Mexico has documented impacts, distinct from the South Central Texas forecast. FOX Weather published photographs credited to storm tracker Mark Sudduth showing flood damage in Lincoln on September 29 and heavy rain along the Rio Ruidoso.
FOX Weather reported three flash flood emergencies in Doña Ana County on Tuesday amid concerns about imminent failure at McLeod Dam. A county spokesperson separately told CBS News that pumps were being brought in to reduce pressure on the dam. Neither report establishes that the dam actually failed.
Citing county officials, FOX Weather said evacuations remained in effect in Rincon early Wednesday, while orders for Salem, Garfield, Hatch and Placitas had been lifted. That describes the morning situation; it does not confirm evacuation conditions later in the day.
Does this establish flooding in California?
The NWS Texas forecast and the reports from FOX Weather and CBS News do not establish Polo-related flooding in the US state of California. Their accounts document New Mexico impacts and forecast risks farther east. They also do not establish that California is free of unrelated flooding.
Why flood concerns could continue into Friday
The NWS expects the front to reach the Coastal Plains by Friday afternoon. Even then, additional storms could fall on ground saturated by Wednesday’s and Thursday’s rain, allowing further flooding. The expected end of the main rainfall window is therefore not a guaranteed end to the danger.
Some storms from Wednesday night through Friday morning could also bring strong winds and hail, although flooding remains the NWS office’s principal concern. Further showers and thunderstorms are possible over the weekend, with rain chances forecast to decrease heading into the following week.
Sources and context
- EWX Area Forecast Discussion e6f38c16-702e-4509-981e-d2ea841fce82National Weather Service Austin/San Antonio
- Texas in bull's-eye of dangerous, tropically enhanced 1,500-mile flood threat covering 11 statesFOX Weather
- Flood Warning VS. WatchNational Weather Service
- 100 million under flood alerts in U.S. after Polo slams Mexico. See forecast maps.CBS News
AI-assisted article checked against the listed sources. NewsJaws did not conduct interviews or attend the reported events.
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