Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 27 2025 19:30:47 FOUS30 KWBC 271930 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 230 PM EST Thu Nov 27 2025 Day 1 Valid 16Z Thu Nov 27 2025 - 12Z Fri Nov 28 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. An instance of urban flash flooding cannot be ruled out across portions of southeastern Florida this afternoon. An approaching cold front will trigger a few outflow-driven thunderstorms that may exhibit relatively slow storm motions due to weak wind fields below 500mb. 1.6 inch PW values and 1000+ J/kg MLCAPE in the pre-frontal airmass both support robust updrafts with locally heavy rainfall. A conditional threat will exist for spotty 1 inch/hr rain rates to impact urban areas between Miami and West Palm Beach. The isolated and conditional nature of this threat precludes any introduction of probabilities/risk areas for this outlook. Cook Day 2 Valid 12Z Fri Nov 28 2025 - 12Z Sat Nov 29 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Chenard Day 3 Valid 12Z Sat Nov 29 2025 - 12Z Sun Nov 30 2025 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF SOUTHEAST TEXAS INTO CENTRAL LOUISIANA... We were able to trim back the northern and eastern extent of the=20 Marginal risk with this update. Showers and embedded thunderstorms=20 will be ongoing Saturday across the region, but the=20 intensity/coverage is generally not expected to result in a flash=20 flood risk. However we should see an uptick in both convective=20 coverage and intensity between 00z-06z Sunday as low level=20 convergence increases across southeast TX. While this activity=20 still should be rather progressive, some brief training is=20 possible, which could locally push rainfall amounts up over 2-3"=20 and result in a localized flash flood risk. The 12z RRFS indicates=20 this potential, producing localized swaths over 3" Saturday night.=20 While the RRFS appears slower with the front than the model=20 consensus, and thus too far west with its QPF max...the idea of=20 some brief training resulting in locally higher rainfall still=20 holds. Thus we will continue to carry a Marginal risk, but keep it=20 confined to southeast TX into southwest LA where the potential for higher rainfall rates is greatest. Chenard Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_y9isghxHrxEKisIghRjY6wLIPeDJMnpc6Gi8S0lLu8v= jTGPXp-Z89TeL1rh5qEvOmkF9-4JqSYR6GbLmGduSt0GxeU$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_y9isghxHrxEKisIghRjY6wLIPeDJMnpc6Gi8S0lLu8v= jTGPXp-Z89TeL1rh5qEvOmkF9-4JqSYR6GbLmGduLw3QSbo$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_y9isghxHrxEKisIghRjY6wLIPeDJMnpc6Gi8S0lLu8v= jTGPXp-Z89TeL1rh5qEvOmkF9-4JqSYR6GbLmGdudlEHZIM$=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .