Area Hydrologic Discussion
— Latest
Threat
POTENTIAL IMPACTS: Life-threatening flooding impacts and catastrophic WHERE: South-central Texas (including portions of the Hill Country) WHEN: Through mid-Thursday morning
Rainfall & Conditions
QPF: Additional 5 - 10", locally higher (HRRR) QPE: 6 - 12" , locally 16+" (72 hr MRMS) Rain Rates: 2 - 4"/hr (HRRR) Soil Moisture: Saturated (NASA SPoRT) Streamflows: Above normal to high (Observed)
Discussion
Widespread life threatening flash and urban flooding, along with continued catastrophic river flooding will continue through at least mid-morning Thursday as persistent heavy rainfall continues across the region. Impressive rainfall totals of 6 - 12", with locally higher amounts exceeding 16", have already fallen across the area of concern over the past 72 hours, allowing for complete saturation of the soil column and completely exhausting infiltration capacity to alleviate runoff. With additional heavy rainfall expected, this is a particularly dangerous situation that has already caused extensive flooding in areas west of San Antonio, and this additional rainfall will likely cause more damage to businesses and homes, trigger water rescues, and create numerous road washouts and closures. Large areas of standing water in low-lying areas, new and renewed river flooding and flooding of low water crossings, arroyos, and normally dry washes are likely. The overnight timing further increases concerns as limited visibility may make identifying flooded roadways and areas exceptionally difficult.
The HRRR-forced National Water Model has been consistently highlighting the potential for rapid-onset and significant flooding across the area of concern, with peak flows expected beginning overnight. The NWM continues to emphasize the potential for significant small stream flooding impacts/responses as the high flow magnitude forecast is indicating widespread annual exceedance probabilities below 20%, with areas as low as 2% between Del Rio and Uvalde, which is one area that is currently experiencing significant flooding. Unit discharge values reinforce this idea, depicting significant high flows during the overnight period. Overall, the vulnerable antecedent conditions and guidance from the NWM increases confidence in the likelihood of life-threatening to catastrophic impacts. The severity of the impacts will be highly dependent on the placement of more intense rainfall.
Addressed To
WFO: MAF, SJT, EWX RFC: FWR, WPC
000 AGUS74 KWCO 160251 AHDNWC Area Hydrological Discussion #147 - EXPERIMENTAL NWS National Water Center - Tuscaloosa, AL 942 PM CDT Wed Jul 15 2026 POTENTIAL IMPACTS: Life-threatening flooding impacts and catastrophic river flooding WHERE: South-central Texas (including portions of the Hill Country) WHEN: Through mid-Thursday morning FORECAST RAINFALL AND ANTECEDENT CONDITIONS... QPF: Additional 5 - 10", locally higher (HRRR) QPE: 6 - 12" , locally 16+" (72 hr MRMS) Rain Rates: 2 - 4"/hr (HRRR) Soil Moisture: Saturated (NASA SPoRT) Streamflows: Above normal to high (Observed) DISCUSSION... Widespread life threatening flash and urban flooding, along with continued catastrophic river flooding will continue through at least mid-morning Thursday as persistent heavy rainfall continues across the region. Impressive rainfall totals of 6 - 12", with locally higher amounts exceeding 16", have already fallen across the area of concern over the past 72 hours, allowing for complete saturation of the soil column and completely exhausting infiltration capacity to alleviate runoff. With additional heavy rainfall expected, this is a particularly dangerous situation that has already caused extensive flooding in areas west of San Antonio, and this additional rainfall will likely cause more damage to businesses and homes, trigger water rescues, and create numerous road washouts and closures. Large areas of standing water in low-lying areas, new and renewed river flooding and flooding of low water crossings, arroyos, and normally dry washes are likely. The overnight timing further increases concerns as limited visibility may make identifying flooded roadways and areas exceptionally difficult. The HRRR-forced National Water Model has been consistently highlighting the potential for rapid-onset and significant flooding across the area of concern, with peak flows expected beginning overnight. The NWM continues to emphasize the potential for significant small stream flooding impacts/responses as the high flow magnitude forecast is indicating widespread annual exceedance probabilities below 20%, with areas as low as 2% between Del Rio and Uvalde, which is one area that is currently experiencing significant flooding. Unit discharge values reinforce this idea, depicting significant high flows during the overnight period. Overall, the vulnerable antecedent conditions and guidance from the NWM increases confidence in the likelihood of life-threatening to catastrophic impacts. The severity of the impacts will be highly dependent on the placement of more intense rainfall. GRAPHICAL REPRESENTATION: weather.gov/owp/operations-ahd Additional National Water Center products are available at: weather.gov/owp/operations //JDP ATTN...WFO...MAF...SJT...EWX ATTN...RFC...FWR...WPC