Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 29 2022 07:33:39 FOUS30 KWBC 290733 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 232 AM EST Tue Nov 29 2022 Day 1 Valid 12Z Tue Nov 29 2022 - 12Z Wed Nov 30 2022 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHERN MISSISSIPPI AND ALABAMA... A strong shortwave trough ejecting out into the Plains today will lead to deepening cyclogenesis over the Upper Midwest with an associated cold front progressing across portions of the lower Mississippi Valley. This surface low and its associated cold front is expected to track quickly across the Plains and into the Midwest. Deep-layered moisture will expeditiously advect northward within the swift southerly low-level flow ahead of this front all the while steep mid-level lapse rates spread out across the region and the airmass becomes more buoyant. The environment will quickly become favorable for organized convection ahead of and along the approaching front. A severe weather outbreak likely develop over portions of the Lower Mississippi Valley, Gulf states and into the Tennessee Valley. While strong winds and hail will likely be the primary threats with any of these storms, especially over the Mississippi/Tennessee Valleys there is a strong potential for brief periods of very intense rainfall particularly across southern portions of Mississippi and Alabama. Some of the latest hi-res guidance show as much as 3 inches/hour streaking across the central Gulf area as one, possibly two, squall lines push through. Even though the bulk of the storms may occur overnight, they will still be strong enough to cause local flash flooding, especially given the moist soils from recent rains over far southern Mississippi and Alabama but forward speed will be a mitigating factor. That said, there may be some stalling of that squall line over far southern Mississippi and Alabama, but a bit inland from the coast. If that happens the flash flooding threat locally could be substantially higher. Areal averages of 2 to 4 inches are forecast for the south-central U.S. but isolated maxes of 5 to 8+ inches will certainly be possible. Amounts in that quantity would soon exceed local FFG guidance and likely lead to scattered to locally widespread flash flooding. A Moderate Risk was raised across southern Mississippi and Alabama. The ongoing Slight and Marginal Risk areas were adjusted to reflect the latest trends and WPC QPF. Campbell/Wegman 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!5EHvE8szrEv6HW5S_SjLljyg4JGQp1rZa2c9qjDaMIOM= Y9r5qxxGTHdKJIXKl1JK4FfIf4hvuykujqBYU-aID5adncg$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5EHvE8szrEv6HW5S_SjLljyg4JGQp1rZa2c9qjDaMIOM= Y9r5qxxGTHdKJIXKl1JK4FfIf4hvuykujqBYU-aIisfOhy4$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5EHvE8szrEv6HW5S_SjLljyg4JGQp1rZa2c9qjDaMIOM= Y9r5qxxGTHdKJIXKl1JK4FfIf4hvuykujqBYU-aICwAJXZU$=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) .