FOUS30 KWBC 081600 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1200 PM EDT Fri May 8 2026 Day 1 Valid 16Z Fri May 08 2026 - 12Z Sat May 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF SOUTHEASTERN LOUISIANA AND SOUTHERN MISSISSIPPI... ...16Z Update... The overnight Slight Risk area was maintained as an area of training showers and thunderstorms take shape across Louisiana and Mississippi. 12Z HREF and RRFS EAS neighborhood probabilities continue to depict a high probability of rainfall exceeding 2 inches in the highlighted area. This aligns with the location of an instability gradient/stationary front analyzed near the Gulf Coast which will focus convection today. Otherwise, the forecast in South Texas remains somewhat unceratin, with some 12Z CAM guidance trending more dry in the area. However, based off of the synoptic setup and moisture profiles outlined previously, thunderstorm clusters capable of producing isolated flash flooding certainly remain plausible. Thus, the Marginal Risk was kept in for this update. Asherman ...Previous Discussion... ...Lower Mississippi Valley/Central Gulf Coast... A robust moisture pool is expected to deepen along the central Gulf Coast today as southwesterly winds amplify ahead of energy moving out of eastern Texas and the northwestern Gulf. This flow will support PWs climbing to around 2 inches along a slow-moving front, or more than 2.5 std dev above normal. The majority of the CAMs are in good agreement indicating a corridor of training convection developing by the afternoon across southeastern Louisiana and southern Mississippi. Given the high moisture content and potential for training, localized totals of 2-3+ inches are possible. High hourly rates within these training storms will pose a risk for flash flooding, particularly in low-lying and urban areas, with the highest potential impact centered along the I-10 corridor. The introduced Slight Risk area reflects high neighborhood probabilities shown by both the HREF and RRFS for amounts exceeding 2 inches. ...South Texas... Farther west, a well-defined mid-to-upper level shortwave/low moving through northern Mexico into West Texas will provide increasing ascent. Moist southerly flow interacting with this feature and upslope into the Sierra Madre Oriental will support storms developing over northeastern Mexico. While much of this activity may remain south of the international border, there are some hi-res members that show some of these convective clusters moving into South Texas. Though model spread is higher in this region, both the HREF and RRFS indicate that localized totals exceeding 2 inches are possible. Therefore, a Marginal Risk was maintained to account for this potential. Pereira Day 2 Valid 12Z Sat May 09 2026 - 12Z Sun May 10 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL GULF COAST INTO THE SOUTHEAST... The previously noted shortwave moving into West Texas on Day 1 is forecast to move eastward along the central Gulf Coast on Saturday. While lingering deep moisture will remain in place, the synoptic signal for organized and widespread heavy rainfall becomes significantly more diffuse. Current model guidance lacks a concentrated signal for high-end totals, suggesting a more isolated or low-end flash flood threat. Given the environment and the potential for antecedent conditions driven the previous day's heavy rains, the current Marginal Risk was maintained for this cycle. But should model trends continue to show a lack of organization, this area may be discontinued in future updates. Pereira Day 3 Valid 12Z Sun May 10 2026 - 12Z Mon May 11 2026 ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF NORTHEASTERN TEXAS, SOUTHEASTERN OKLAHOMA, SOUTHERN ARKANSAS, AND NORTHERN LOUISIANA... Shortwave energy diving into the base of broader scale trough will drive a cold front southward across the region. Southerly flow ahead of the boundary will boost PWs to over 1.5 inches. This moisture, combined with favorable upper jet forcing, will support storms developing along and ahead of the front. While model spread is currently too high to support a higher risk area and the signal for widespread heavy totals remains muted, locally intense rates along with some areas of repeating cells could result in isolated flash flooding. Pereira Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt