Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 27 2023 08:30:06 FOUS30 KWBC 270830 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 429 AM EDT Wed Sep 27 2023 Day 1 Valid 12Z Wed Sep 27 2023 - 12Z Thu Sep 28 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHEAST AND OHIO VALLEY... ....Ohio Valley... A slow moving mid- and upper-low will continue to make its way eastward from the Mid-Mississippi Valley early this morning into Indiana or far southern Michigan by late this coming night. Weak and difficult to time shortwave energy...but significant in helping trigger and focus convection...will be rotating around the low as it tracks eastward during the period. South to southwest low level winds will help draw deeper moisture back into the area with precipitable water values increasing to around 1.25 inches within the outlook area ahead of the approaching dynamics. Deterministic guidance still shows a ribbon of elevated MLCAPE between 1000-1500 J/kg. The 27/00Z HREF mean showed another increase in QPF along an east to west axis across parts of Kentucky on Wednesday evening...which looks plausible for a region of training on the south side of the low. As a result...expanded the Marginal risk a bit south and westward here.=20 Overall...though...the not many changes were needed to the previous Day 2 ERO as it becomes the current Day 1 ERO.=20 ....Southeast U.S.... A near carbon-copy outlook of recent days given a pool of 2-2.5" PWs to go along with a quasi-stationary front draped over Florida and an upper trough over the Gulf of Mexico. Wednesday features a little more instability across the Gulf side of the Florida rather than the Atlantic for now, maintained the focus for Excessive Rainfall from southwest Florida on north to southern Georgia and southern Alabama. As much as 500-1,000 J/kg of MLCAPE will be present across central and northern Florida, and with such a tropical air-mass in place, rainfall rates could approach 3"/hr in the strongest storms. A Marginal Risk for Excessive Rainfall remains in place as urbanized communities and poor drainage areas are most vulnerable to possible flash flooding. Bann 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!_ceX43AAIcrJ1hU-zqTR3_-x065sNoGAITYOqiWcPMmG= UPbXF4i6yjCOXn-4qt9SLt_5QpyRODZVnM_uvaJ7zNY2YAg$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_ceX43AAIcrJ1hU-zqTR3_-x065sNoGAITYOqiWcPMmG= UPbXF4i6yjCOXn-4qt9SLt_5QpyRODZVnM_uvaJ7Hr9wPZc$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_ceX43AAIcrJ1hU-zqTR3_-x065sNoGAITYOqiWcPMmG= UPbXF4i6yjCOXn-4qt9SLt_5QpyRODZVnM_uvaJ7Z85lE_8$=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) .