Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 30 2023 08:12:42 FOUS30 KWBC 300812 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 412 AM EDT Sun Jul 30 2023 Day 1 Valid 12Z Sun Jul 30 2023 - 12Z Mon Jul 31 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHWEST, THE NORTHERN PLAINS TO CENTRAL PLAINS/LOWER MISSOURI VALLEY, AND SOUTHERN APPALACHIANS/SOUTHEAST... ....Southwest... An inverted upper trough will continue to lift northeast from northern Mexico into the southwestern U.S., pushing the subtropical ridge farther to the east and allowing deeper moisture to advect across Arizona through the Four Corners region and into the central Rockies. The general consensus of the guidance continues to show PWs increasing to over 1.5-2 standard deviations above normal across southern California and along the southern Colorado Basin into the Four Corners region today. This moisture along with decreasing heights aloft is likely to support more widespread afternoon and evening thunderstorms and an increased threat for locally heavy amounts and isolated flash flooding. ....Northern to central Plains and lower Missouri Valley... Mid-level shortwaves moving off of the top of the ridge may pose a localized heavy rainfall threat as they interact with a plume of deeper moisture fed by southeasterly low level flow. While there are differences in the details, the overnight CAM guidance is highlighting two areas of storm development later today. One over southern Montana and central Wyoming, with storms spreading east into western South Dakota and Nebraska. The highest probabilities from the HREF for heavy amounts (greater than 2 inches) currently centers northeastern Wyoming into southwestern South Dakota. This may create isolated flash flooding concerns across the region before these storms move into the less flood prone Sandhills of central Nebraska. Storms that continue or develop farther downstream may also produce locally heavy rain and pose an isolated threat for flash flooding across portions of the lower Missouri Valley as well. Guidance is also showing storms developing farther to the north across northern Montana and southern Canada before moving into western North Dakota, with some of the CAMs showing localized heavy amounts across portions of northeastern Montana into western North Dakota.=20 ....Southern Appalachians/Southeast... Plenty of moisture (PWs around 1.75 inches or higher) is expected to remain along and south of a frontal boundary as it continues to dip south through the Carolinas today. This moisture interacting with energy associated with overnight convection over the Ohio and Tennessee valley may produce some locally heavy amounts as it moves across the southern Appalachians and into the Southeast later today. This deep moisture will extend south to the Gulf Coast and across the Florida peninsula, bolstering the potential for heavy downpours and localized runoff concerns as the more typical sea breeze convection develops during the afternoon. Pereira Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7RO7ijPWa0JEuaKFKiirpoxi28lT1hZHi6tLO6HIEDiU= fB-TOLf_jk2aOsvtt4K2p9smCdr2tZKj0RKF4qNdPgAHDLk$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7RO7ijPWa0JEuaKFKiirpoxi28lT1hZHi6tLO6HIEDiU= fB-TOLf_jk2aOsvtt4K2p9smCdr2tZKj0RKF4qNdM3PTN7o$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7RO7ijPWa0JEuaKFKiirpoxi28lT1hZHi6tLO6HIEDiU= fB-TOLf_jk2aOsvtt4K2p9smCdr2tZKj0RKF4qNdXPi9Scg$=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) .