Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 08 2025 20:16:44 FOUS30 KWBC 082016 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 416 PM EDT Tue Apr 8 2025 Day 1 Valid 16Z Tue Apr 08 2025 - 12Z Wed Apr 09 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF SOUTH FLORIDA... ....16z update... Excessive rainfall potential will likely remain confined to peak heating hours prior to 00z (8pm EDT) today. Convective ingredients remain almost the same as the overnight issuance with some subtle downward trends on PWATs (1-1.5") and CAPE (1000-2000 J/kg). Thus, non NAM CONEST CAMs have suggested drier/more progressive solutions in QPF. Localized flash flooding is still possible due to a potential synoptic seabreeze--cold front connection. Kebede ....Previous Discussion... Deep southwest flow is occurring ahead of an advancing cold front across the FL Peninsula this morning. Precipitable water values have increased to 1.7-1.9" in association with the front, and SB CAPE should maximize in the 2000-2500 J/kg range per the 00z HREF. Low-level inflow (non-zero) and effective bulk shear (20-40 kts) are more than sufficient for convective organization, across South FL typically, and whether or not a localized flash flood risk fully materializes depends upon whether or not an East Coast seabreeze front can develop and focus convection with the well- timed arrival of the front (near peak daytime heating), which could anchor convection in the large urban area of South FL as it is unlikely to progress inland within this synoptic pattern. In this sort of atmosphere, hourly rain totals to 2.5" (as depicted by CAMs) and overall totals to 5" are possible (as 00z HREF 40-km neighborhood probabilities for 3" exceedance are as high as 30-60% along the immediate Gold Coast. Considering the urban environment, ingredients available, and mesoscale guidance signal, maintained the inherited Marginal Risk for South FL. Churchill/Roth Day 2 Valid 12Z Wed Apr 09 2025 - 12Z Thu Apr 10 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kebede Day 3 Valid 12Z Thu Apr 10 2025 - 12Z Fri Apr 11 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kebede Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8OFmI7xLztcclyCqsSE9OvJMGHDHkRWkn8G3ABXVoa8t= kcj9gRr8RqZL6-CLhQn4gp8ylN9D2ocLVUS5Van2POdTlJ0$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8OFmI7xLztcclyCqsSE9OvJMGHDHkRWkn8G3ABXVoa8t= kcj9gRr8RqZL6-CLhQn4gp8ylN9D2ocLVUS5Van2YTgX49s$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8OFmI7xLztcclyCqsSE9OvJMGHDHkRWkn8G3ABXVoa8t= kcj9gRr8RqZL6-CLhQn4gp8ylN9D2ocLVUS5Van2cOOIGtQ$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .