Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Aug 27 2023 04:16:39 AWUS01 KWNH 270416 FFGMPD TNZ000-KYZ000-ILZ000-MOZ000-ARZ000-271015- Mesoscale Precipitation Discussion 0986 NWS Weather Prediction Center College Park MD 1215 AM EDT Sun Aug 27 2023 Areas affected...Southeast MO...Northeast AR...Northwest TN...Western KY...Southern IL Concerning...Heavy rainfall...Flash flooding possible Valid 270415Z - 271015Z SUMMARY...Showers and thunderstorms are expected to develop and gradually expand in coverage overnight with very heavy rainfall rates. Scattered instances of flash flooding will be possible. DISCUSSION...The latest GOES-E Proxy Visible satellite imagery shows a very well-defined and slow-moving MCV over southeast MO. This energy will be drifting off to the southeast overnight down toward the MO Bootheel and is expected to work in tandem with a very moist and modestly unstable airmass for some nocturnally enhanced areas of very heavy showers and thunderstorms. MLCAPE values are generally on the order of 500 to 1000 J/kg across areas of northeast AR through western TN and up into southeast MO, with lesser values seen farther northeast across southern IL and western KY. However, PWs are very high with values of 2.0 to 2.25 inches and reflective of a deep tropical environment. There is substantial uncertainty with some of the details of the convective evolution overnight as a large number of the 00Z HREF CAM members are quite aggressive with their QPF. Already, the HREF guidance appears to be overdone with its amounts heading through the 06Z time frame based on the latest satellite and radar trends. However, some tightening of the mid-level circulation is expected, and there will likely be somewhat stronger moisture convergence and forcing that sets up around the southern and eastern flanks of the MCV after 06Z and closer to 09Z that will favor somewhat better concentrations of heavy shower and thunderstorm activity. There is a small cluster of slow-moving storms right now over southeast MO just to the northeast of Poplar Bluff which may be the beginning of some upscale convective growth over the next few hours. Regardless of the exact details, the convection overnight will be capable of extremely heavy rainfall rates given the tropical environment that is in place, and with slow cell-motions and potential for localized backbuilding and training of cells, some locally very heavy rainfall amounts will be possible. Expect rainfall rates to potentially reach 2.5 to 3 inches/hour, and some small-scale storm total amounts of 3 to 5 inches to be possible going through dawn. This will foster a threat for at least scattered instances of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7NGOfDTKvzZuDK3hiX1UYDHrRhiQR9nSnsmkQpjy8RDzNDKyJyhmYi9NRpMCL0opP7vj= RPDKY6yKzQxUDtTEiR96mf8$ for graphic product... ATTN...WFO...LSX...LZK...MEG...PAH...SGF... ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC... LAT...LON 38228947 38118881 37558819 36838820 36028889=20 35549013 35719112 36459151 37409127 37969046=20 =20=20=20=20=20=20=20=20=20=20=20=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) .