Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Mar 05 2023 15:40:14 FOUS30 KWBC 051540 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1039 AM EST Sun Mar 05 2023 Day 1 Valid 16Z Sun Mar 05 2023 - 12Z Mon Mar 06 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Scattered to numerous showers and thunderstorms are expected later this afternoon and evening across the east-central Florida Peninsula in an area with onshore flow, modest axis of instability, and in the vicinity of a surface boundary. Recent runs of the HRRR and other 12Z hi-res guidance still shows the possibility for isolated intense rain rates within the merging/colliding convective clusters. However, the isolated nature and relatively dry conditions should keep any flooding issues mostly nuisance with isolated instances of minor urban flooding runoff. No risk area was defined with this update. Taylor Day 2 Valid 12Z Mon Mar 06 2023 - 12Z Tue Mar 07 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Putnam Day 3 Valid 12Z Tue Mar 07 2023 - 12Z Wed Mar 08 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS AND MIDDLE/LOWER MISSISSIPPI VALLEY... The upper-level pattern over the CONUS will be slowly amplifying Tuesday as a broad trough remains in place over the West and weak ridging begins to build downstream over the Mississippi Valley, with southwest flow in place over the central CONUS. At the surface, a front will be pushing southward over the Middle/Lower Mississippi Valley and Southern Plains overnight Monday and into the day Tuesday, eventually slowing and likely becoming stationary in the vicinity of the Red River Valley. Precipitable water anomalies across the region begin to increase by Tuesday evening into early Wednesday morning 2-2.5 standard deviations above the mean as a combination of return flow moisture from the Gulf of Mexico as well as an additional moisture stream to the southwest from the Pacific meet over the Southern Plains. Storms are expected to develop and increase in coverage later Tuesday into the early morning hours Wednesday as convergence and lift increase along and over the generally east-west stationary boundary ahead of a weak surface wave and also an inverted surface trough extending to the north. Model guidance indicates areal average rainfall totals between 0.5-1", with increasing likelihood later in the day 3 period early Wednesday morning. Recent rainfall has led to wet antecedent conditions particularly from southeastern Oklahoma into Arkansas and southern Missouri. Forecast QPF amounts also indicate the potential for localized totals of 2-3" with this convection, supported by the increasing PW values, which would lead to the threat of at least isolated instances of flash flooding. A Slight Risk was considered for this outlook given the potential for these localized heavier totals. However, there is still enough model disagreement in the placement of the surface boundary and the subsequent eventual location and coverage of storms to wait until there is more confidence in a higher threat for more scattered flash flooding.=20 Putnam Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9idwHka5RwfDAdV9PStVHiRKoI3FgDQZGN-yXflT9hD-= bA08AS7kjKXsGQYknKRe1xx5_71xXbfiNTHd_DX-f9xf-S4$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9idwHka5RwfDAdV9PStVHiRKoI3FgDQZGN-yXflT9hD-= bA08AS7kjKXsGQYknKRe1xx5_71xXbfiNTHd_DX-QTu9qqg$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9idwHka5RwfDAdV9PStVHiRKoI3FgDQZGN-yXflT9hD-= bA08AS7kjKXsGQYknKRe1xx5_71xXbfiNTHd_DX-oEdwI44$=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) .