Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Apr 14 2025 15:48:26 FOUS30 KWBC 141548 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1148 AM EDT Mon Apr 14 2025 Day 1 Valid 16Z Mon Apr 14 2025 - 12Z Tue Apr 15 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF WEST VIRGINIA, SOUTHERN OHIO, AND EASTERN KENTUCKY... Based on latest model guidance, the Marginal Risk area has been=20 expanded to include most of West Virginia and portions of southern Ohio and eastern Kentucky. The CAMs continue to show the potential for training this afternoon and evening as an ENE-WSW oriented=20 cold front moves through the region with easterly storm motion.=20 This could result in localized QPF values reaching up to 1.5-2.5+=20 inches. Additionally, the ingredients will be in place for=20 stronger storms to produce rainfall rates greater than 1 inch per=20 hour, with an axis of high moisture ahead of the front with PWAT=20 values 1.25-1.5 inches and MLCAPE greater than 1000 J/Kg. Given=20 recent rainfall and saturated soils, FFGs are quite low in this=20 region, and there is a chance they could be exceeded, leading to=20 isolated to scattered flash flooding concerns.=20 Dolan Day 2 Valid 12Z Tue Apr 15 2025 - 12Z Wed Apr 16 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Wegman Day 3 Valid 12Z Wed Apr 16 2025 - 12Z Thu Apr 17 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NORTHERN CALIFORNIA AND WESTERN NEVADA... An upper level low centered off the coast of central California Wednesday morning will drift eastward towards the coast through the day. This upper low will spread increasingly cold air in the upper levels over California and Nevada. This will increase the instability over the region. Meanwhile, a plume of Pacific moisture will also move into the region, raising PWATs above 0.75 inches in some areas, which is over 2 sigma above normal and above the 95th percentile compared to climatology for the region. Finally, plentiful warm air in the lower levels of the atmosphere will both contribute to that instability, as well as raise snow levels to 9-10k ft, so the vast majority of expected precipitation in and around the Sierras will be in the form of rain. Since expected MUCAPE values will increase to around 500 J/kg over the area, the storms that form will be capable of producing cores of heavier rain, which combined with snowmelt in the Sierras will support an isolated flash flooding risk, especially in the most prone valleys and low lying areas. Thus, in coordination with REV/Reno, NV and STO/Sacramento, CA forecast offices, a Marginal Risk was introduced with this update. Expect with changing model guidance that the Marginal area will shift between the morning model run cycle and Wednesday's event, particularly across western Nevada, as the amount of convection that may cross the Sierras becomes more clear. Wegman Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_0uxt9tDcXtv2eoJ6Z20qOheTF86EwBElSERVn8-437a= vixmwaJuIyp7-WkoReQoGzISa-GFd9ly-6x7k0ZfopIzbr8$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_0uxt9tDcXtv2eoJ6Z20qOheTF86EwBElSERVn8-437a= vixmwaJuIyp7-WkoReQoGzISa-GFd9ly-6x7k0Zf4UHmnFM$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_0uxt9tDcXtv2eoJ6Z20qOheTF86EwBElSERVn8-437a= vixmwaJuIyp7-WkoReQoGzISa-GFd9ly-6x7k0ZfgnzOQDA$=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) .