Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 24 2025 07:59:23 FOUS30 KWBC 240759 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Thu Apr 24 2025 Day 1 Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE CENTRAL/SOUTHERN PLAINS AND IOWA... The latest suite of guidance continues to be be highly variable=20 with the placement of highest QPF; however persisted with increases over Iowa as well as Oklahoma and Texas. The Slight Risk saw a=20 southward expansion for the Hill Country and to the northeast=20 placing the northern boundary into central Iowa. Meanwhile there=20 was a reduction across western Oklahoma and along the Missouri and Kansas border. Areal averages of 1 to 2 inches with local maximums of 4+ inches possible. Multiple clusters of thunderstorms will likely be ongoing. With peak heating and the increased instability there will be renewed rounds of showers and thunderstorms. Since this is likely to occur over=20 many of the same areas hit with recent heavy rain this will once=20 again renew the potential for localized flash flooding over=20 portions of the Southeast. There will be a steady influx of Gulf=20 moisture streaming over the stalled boundary which will maintain=20 support for heavier rainfall with the strongest storms, and greater coverage of showers and storms in general. A Marginal Risk covers=20 the northern Gulf states and Southeast. Campbell Day 2 Valid 12Z Fri Apr 25 2025 - 12Z Sat Apr 26 2025 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS, MID-MISSISSIPPI VALLEY, OHIO VALLEY, AND PORTIONS OF THE NORTHEAST... A strengthening surface low developing ahead of a strengthening upper level shortwave trough will drive the storms from a forcing standpoint through the period. Starting in the Plains it will track northeast into the Great Lakes Friday evening, with showers and=20 storms forming along the cold front to the south and east of the=20 low center. This will bring periodically heavy rainfall to=20 portions of the Northeast, which has been in a drier period the=20 past week. Gulf moisture continuing to advect in from the south=20 will lead to shower and thunderstorm activity starting Friday=20 afternoon across the Tennessee and Ohio Valleys, and continuing=20 into Friday night as the front lags behind (south and west) of the=20 surface low. Meanwhile, the trailing (western) end of the cold=20 front may be the trigger for additional thunderstorms into southern Oklahoma, north Texas, and the southern Texas Panhandle.=20 In coordination will the offices in the Northeast the Marginal Risk was removed from New Hampshire, Vermont, much of New York and northeast Pennsylvania. This area has been drier of late and with green up already in progress, much of the rain will be absorbed with minimal if any flooding possible. Elsewhere, the Marginal had minor reshaping to reflect the latest WPC QPF and model trends. Campbell/Wegman Day 3 Valid 12Z Sat Apr 26 2025 - 12Z Sun Apr 27 2025 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS AND FOR PORTIONS OF NEW ENGLAND... ....New England... Showers and thunderstorms are expected to pass through New England thanks to upper level shortwave energy and wavy surface fronts.=20 The flow is expected to be fairly progressive so it will help limit the potential for flash flood. Given the recent QPF trends and=20 placement, the inherited Marginal Risk area was significantly=20 modified to only include northeast Vermont, northern New Hampshire=20 and the majority of the state of Maine.=20 ....Southern Plains... The steady influx of rich moisture ahead of a deeply strengthening storm system ejecting into the Plains will fuel rounds of heavy=20 rain and thunderstorms across portions of the central U.S. from the weekend into next week. Guidance has improved its focus on where the higher QPF will occur. The old Day 4 Marginal Risk was reduced out of Nebraska and Kansas, now spanning from Texas to western Arkansas as the new Marginal Risk area for this period. Heavy rain will be favorable with the upper trough diffluence combined with=20 front/dryline instabilities. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREfmzX7WYI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREftrOTn8Y$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-YzSAaXAoiCA7YSOrhljjwIE5bBs-U01S_OG4tpbD_ki= Zg5J6TsxvpOGc26GoW4RR4wXu_5WX5jU8nKYzREfMZyPDBE$=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) .