Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 15 2025 00:33:14 FOUS30 KWBC 150032 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 832 PM EDT Mon Apr 14 2025 Day 1 Valid 01Z Tue Apr 15 2025 - 12Z Tue Apr 15 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN AND NEAR SOUTHERN WEST VIRGINIA... Convective trends in and near WV have led to a reorientation of the Marginal Risk, extending from new convection in eastern KY across southern WV into southwest VA. The CAMs and available MU CAPE show the potential for training over the next 2-4 hours. This could=20 result in localized QPF values reaching up 2-3", with hourly totals up to 1". Given recent rainfall and saturated soils, FFGs are=20 quite low in this region, and there is a chance they could be=20 exceeded, leading to isolated to widely scattered flash flooding=20 concerns. Roth/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. Dolan 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 is forecast to slowly drift east towards the California Coast on Wednesday, which will result in decreasing heights and cooling upper levels over California and Nevada. Instability will increase across this region as lapse rates steepen, and there will likely be enough large scale ascent to support showers and thunderstorms across portions of northern California and the Sierra Nevada. PWATs are expected to increase ahead of the low, reaching 2+ standard deviations above normal with values up to 0.75-1 inches in some locations. There should be enough moisture and instability for locally moderate to heavy rainfall in thunderstorms, which supports a Marginal risk area. The dominant precipitation type will be rain, but some precipitation is expected to fall as snow in the Sierra Nevada, mainly above 8000 ft with the best snow potential above 10000 ft. Snow melt could contribute to flooding concerns where rain falls on top of snow, but this should have limited impacts. Some rain may make it east of the Sierra into western Nevada, but there is uncertainty as to how much. Dolan Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7Dnf6DCeD_26LnzKWFXgcDtHjRF_herVGXlvCGuEaZ-C= LQUQPWcDxzeBWUxegIsrieMmRaGywUfWfPDu9ra_AiAc-gE$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7Dnf6DCeD_26LnzKWFXgcDtHjRF_herVGXlvCGuEaZ-C= LQUQPWcDxzeBWUxegIsrieMmRaGywUfWfPDu9ra_J4e05PY$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7Dnf6DCeD_26LnzKWFXgcDtHjRF_herVGXlvCGuEaZ-C= LQUQPWcDxzeBWUxegIsrieMmRaGywUfWfPDu9ra_ZhTJ0d0$=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) .