Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 27 2023 14:02:59 AWUS01 KWNH 271402 FFGMPD SCZ000-GAZ000-271900- Mesoscale Precipitation Discussion 0354 NWS Weather Prediction Center College Park MD 1002 AM EDT Sat May 27 2023 Areas affected...Coastal GA...Southern Coastal SC Concerning...Heavy rainfall...Flash flooding possible Valid 271400Z - 271900Z SUMMARY...A complex of vigorous thunderstorms along the northern and western flanks of a consolidated low level circulation center looks to move ashore this morning and linger into early this afternoon. The storm's slow movement and continued influx of low level moisture may result in storms capable of causing localized flash flooding. DISCUSSION...Upper level analysis depicts a quasi-stationary 500mb low off the coast of GA while the lower level circulations at 700mb and 850mb remain offset and titled in the vertical to the south and east of the 500mb low. These lows should become better aligned later today, suggesting the potential for additional strengthening of the occluding surface low off the coast. GOES-16 IR imagery shows a steady and healthy cluster of bubbling convection on the northern and western flanks of the 700mb low circulation (approximation estimated by RAP mesoanalysis) while strong easterly 850mb winds (to the tune of close to 50 knots) improves 850mb moisture transport. KCLX radar estimates showed these storms off the coast were producing as high as 3"/hr rainfall rates, although these have backed off in recent runs after 12Z. The two key factors in this forecast are where does the storm's low-mid level circulation track and can these storms sustain themselves along the coast to produce Excessive Rainfall rates. Addressing the first part, area averaged RAP soundings encompassing the area of interest off the coast show clashing wind regimes with N-ENE winds from the surface-800mb, while winds are more out of the south in the 200-700mb layer. This should eventually lead to the low drifting north as convective towers feel the push of those southerly mid-upper level winds, but presently, the low level easterlies are acting to counter those winds aloft and push the low level circulation closer to the coast. These storms should be able to sustain themselves as favorable diffluence aloft and ample moisture wrapping itself around the circulation also coincides with an increase in MUCAPE. The MUCAPE is the biggest limiting factor as values increase to close to 250J/kg along the coast. These meager instability values, however, also reside within an LCL-EL layer averaged 90% RH regime and warm cloud layers 10,000 feet deep. Hourly rates could top 2"/hr within the deepest convection, but note there will likely be a sharp drop off in rainfall to the north and west where little instability is present. Poor drainage areas and urbanized communities are most prone to possible flash flooding. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_AiRpzion4TJWUiJZeyaegfiTDILTIMK4KdARHTvJiZCpcnCvCD9PvSPE7FMFIZxwl-D= sjj9rxBKhL_sbvRZnK_3jnk$ for graphic product... ATTN...WFO...CHS... ATTN...RFC...SERFC...NWC... LAT...LON 32538051 32508036 32398026 32138050 31868077=20 31708089 31408118 31458142 31698136 32018121=20 32248100 32448073=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) .