Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 16 2024 07:42:32 FOUS30 KWBC 160742 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 342 AM EDT Tue Apr 16 2024 Day 1 Valid 01Z Tue Apr 16 2024 - 12Z Tue Apr 16 2024 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS EASTERN PORTIONS OF THE NORTHERN PLAINS SOUTHWARD THROUGH MUCH OF THE MISSISSIPPI VALLEY... Showers and thunderstorm are expected to align near and north of=20 an east-west orientated warm frontal boundary that is stretched=20 across the eastern portions of the Plains and the Ohio Valley. The=20 highest rainfall rates and accumulation will likely be concentrated along the Minnesota/Iowa border where instability will be most=20 supportive to produce 1-2"/hr rainfall over this area, which will=20 likely exceed 1hr FFG in spots. One limiting factor for flash=20 flooding will be the swift movement of cells, limiting the duration of heavy rates. Training/backbuilding near the warm front could=20 help accumulations to reach or exceed 5 inches. Although there may be some 1hr and 3hr FFG exceedance, the=20 coverage and magnitude of impacts are expected to remain below=20 Slight risk levels. The main threat will be to urban areas, where=20 the intense rates may lead to localized flash flooding. Outside of=20 urban areas the dry ground and limited green vegetation may allow=20 for some excess runoff, however these impacts are expected to=20 remain isolated as well. A Marginal Risk area spans from the eastern Dakotas, Upper/Central Mississippi Valley and across parts of the Mid-Mississippi Valley. Campbell Day 3 Valid 12Z Wed Apr 17 2024 - 12Z Thu Apr 18 2024 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE GREAT LAKES, OHIO VALLEY AND WESTERN PARTS OF THE NORTHEAST... 20z Update: Only minor changes to the inherited Marginal risk. Convection moving across the OH Valley will be strong and capable of producing high rainfall rates, but should generally be progressive in nature. There is less instability with eastward extent, which should result in lower rainfall rates. But given the above average soil saturation and streamflows over portions of PA and NY the Marginal looks good. Chenard ....Previous Discussion... Showers and thunderstorms will shift east as the closed low and fronts advance through the Ohio Valley toward the Mid-Atlantic. Much of the guidance has 1 to 2 inches for this period for parts of the Great Lakes, eastern Ohio Valley and portions of the Northeast. This part of the country has much lower FFG guidance from antecedent rain thus are more sensitive to additional rainfall. A Marginal Risk spans from Michigan/Wisconsin south to Kentucky and east into western New York, Pennsylvania and Maryland. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4_40wso0brJXjhMPAYU7Q0ITDu-J593ynfXPf1GenQJw= 5WRGmGnokJqEmf8vpP3OVGTSa_cUnaKZqvj5fVfFBLexmuc$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4_40wso0brJXjhMPAYU7Q0ITDu-J593ynfXPf1GenQJw= 5WRGmGnokJqEmf8vpP3OVGTSa_cUnaKZqvj5fVfFT8Epre4$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4_40wso0brJXjhMPAYU7Q0ITDu-J593ynfXPf1GenQJw= 5WRGmGnokJqEmf8vpP3OVGTSa_cUnaKZqvj5fVfF6-nlBG4$=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) .