FOUS30 KWBC 200901 AAA QPFERD Excessive Rainfall Discussion...UPDATED NWS Weather Prediction Center College Park MD 401 AM EST Thu Nov 20 2025 Day 1 Valid 12Z Thu Nov 20 2025 - 12Z Fri Nov 21 2025 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF SOUTH-CENTRAL TEXAS, INCLUDING PORTIONS OF THE HILL COUNTRY AND SOUTHERN CALIFORNIA... Maintained the targeted Moderate Risk for portions of Soth-Central Texas given persistent signals for localized 5"+ storm totals from the HREF and the RRFS guidance. That amount of rainfall may result in numerous instances of flash flooding in a relatively small area (with higher confidence overall in locally significant flash flooding as opposed to the total areal coverage). The overnight runs of the HREF and RRFS While 6-hr FFG exceedance probs from the HREF and RRFS both rise to at least 60 percent later today (generally in the morning perhaps into early afternoon) before enough westerly flow develops in the mid-levels which shifts the focus farther eastward. The probabilities diminish during the afternoon and evening. As a result...expanded the surrounding Marginal/Slight risk areas just a bit in the inflow region. Some nudges were made to the placement of the western/northern boundary of the northern Slight Risk area based on latest probabilistic guidance. Some lingering questions remain regarding the eastward extent of both the South-Central TX and Ozarks clusters of convection...however. Introduced a Marginal risk area across parts of southern New Mexico which was a continuation of the area in effect until 20/12Z...as convection moves eastward in response height falls and increasingly difluent flow aloft. ..California... Decided to upgrade to a Slight Risk area for portions of coastal Southern California as the next area of low pressure over the eastern North Pacific drops along the California coast and brings another round of rainfall later today into early Friday. There has been an uptick in rainfall amounts in the numerical guidance over the past 24 hours but still generally under an inch...although locally higher amounts could fall in terrain. Concern is that antecedent conditions have been wet for the better part of a week...suggesting some of area could be more sensitive to run off problems even away from the highly urbanized areas. Bann Day 2 Valid 12Z Fri Nov 21 2025 - 12Z Sat Nov 22 2025 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE OHIO VALLEY AND PORTIONS OF THE SOUTHWEST US... Model guidance continues to lift the Plains system northward into portions of the Ohio Valley. Above normal levels of moisture being transported into the region from the south and encountering an east to west oriented boundary...there is still the possibility for isolated areas of moderate to heavy rainfall that leads to spotty problems from run- off. However...the flow aloft becomes increasingly flat and confluent during the day which will reduce the risk of any excessive rainfall. In California...only limited changes necessary from the previous forecast due to general run- to- run continuity with heaviest rainfall still trending closer to the southern Peninsular Range with an extension of convection back over the southeast CA deserts and southwest AZ. For now, will maintain relatively continuity of the MRGL with some minor adjustments overall. Bann Day 3 Valid 12Z Sat Nov 22 2025 - 12Z Sun Nov 23 2025 The probability of rainfall exceeding flash flood guidance is less than 5 per cent. Bann 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