Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 25 2023 07:41:09 FOUS30 KWBC 250741 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 240 AM EST Sat Nov 25 2023 Day 1 Valid 12Z Sat Nov 25 2023 - 12Z Sun Nov 26 2023 ....A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR SOUTH FLORIDA... Showers and thunderstorms should attempt to attain some level of organization near the Gold Coast this period as instability slowly increases into the 500-1000 J/kg range in and near a coastal front, precipitable water values lie in the 1.5-2" range, and enough effective bulk shear is expected due to surface easterly flow conflicting with 850-400 hPa mean westerly flow. This wind conflict with height could help tie convection near the coast and keep storms from showing much movement, which would be a problem as hourly rain totals to 2.5" would be possible where storms form. The 00z HREF shows a high chance of 3"+ amounts in the Gold Coast, but saves its best chances for 5"+ for the Gulf Stream just offshore. There is quite the spread in the guidance here, with the global models a bit less impressed than the mesoscale guidance. Regardless, the excessive rainfall threat appears to be isolated. Since the synoptic pattern looks favorable, added a Marginal Risk of excessive rainfall/flash flooding for South Florida. Isolated problems are possible in urban where rain rates overwhelm drainage. Roth Day 2 Valid 12Z Sun Nov 26 2023 - 12Z Mon Nov 27 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Roth Day 3 Valid 12Z Mon Nov 27 2023 - 12Z Tue Nov 28 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Roth Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!64BTpymiNOrfFD5Rn1gKRiXKv1pViS-ax2ib_-0zunPo= 8BbQmdKceaKAu5BWxSIIFGXtEJZJD19k66RBD1QgNIC8IKk$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!64BTpymiNOrfFD5Rn1gKRiXKv1pViS-ax2ib_-0zunPo= 8BbQmdKceaKAu5BWxSIIFGXtEJZJD19k66RBD1Qg6GZFXHI$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!64BTpymiNOrfFD5Rn1gKRiXKv1pViS-ax2ib_-0zunPo= 8BbQmdKceaKAu5BWxSIIFGXtEJZJD19k66RBD1Qghdzeb20$=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .