Subj : MESO: Heavy Rain/Flooding To : All From : Mike Powell Date : Sun Aug 27 2023 07:19:00 AWUS01 KWNH 271003 FFGMPD TNZ000-KYZ000-ALZ000-ILZ000-MSZ000-MOZ000-ARZ000-271600- Mesoscale Precipitation Discussion 0988 NWS Weather Prediction Center College Park MD 601 AM EDT Sun Aug 27 2023 Areas affected...Portions of the Lower OH Valley and Mid-South Concerning...Heavy rainfall...Flash flooding possible Valid 271000Z - 271600Z SUMMARY...A threat for some flash flooding will continue through the morning hours across portions of the Lower OH Valley and potentially extending down across the Mid-South from heavy showers and thunderstorms. DISCUSSION...The latest GOES-E Proxy Visible satellite imagery continues to show a very well-defined and slow-moving MCV over southeast MO. This energy is expected to continue drifting generally off to the southeast through the morning hours with the MCV tracking into western KY by midday. This energy should continue to interact with a very moist and modestly unstable airmass for some bands of heavy shower and thunderstorm activity. MLCAPE values are generally on the order of 500 to 1000 J/kg across areas of eastern AR, central and western TN and also western KY. PWs remain very high with values of 2.0 to 2.25 inches and characteristic of an airmass that is deeply tropical in nature. The latest radar imagery does show an axis of convection becoming a bit more focused across areas of southern IL around the eastern flank of the MCV, and this band of convection should tend to gradually advance or refocus farther down to the southeast into western KY going through the morning hours. Meanwhile, farther down to the south, there is a broken band of convection impacting areas of eastern AR, northwest MS and western TN. This activity is generally more progressive and should continue to advance off to the east or east-southeast this morning. The latest HRRR guidance supports areas of western KY seeing the heaviest rainfall potential this morning, with the 06Z HREF displaced a bit farther south into areas of northwest TN. However, the latest radar trends would support portions of southern IL and eventually western KY. The guidance throughout much of the night has been notably overdone with its QPF, but the latest satellite and radar trends do suggest heavier rainfall potential beginning to materialize. Expect rainfall rates to potentially reach 2.5 to 3 inches/hour with the stronger storms, and some small-scale storm total amounts of 3 to 5 inches going through the late morning hours. This will maintain a threat for flash flooding as a result. Orrison ATTN...WFO...HUN...JAN...LSX...LZK...MEG...OHX...PAH... ATTN...RFC...LMRFC...NCRFC...OHRFC...SERFC...NWC... LAT...LON 38118981 38068851 37348735 36298723 34988766 33998882 34029061 34619127 35009115 35369017 36008971 36568982 37009019 37659036 = = = --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .