Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Mar 27 2023 02:08:51 AWUS01 KWNH 270208 FFGMPD GAZ000-ALZ000-MSZ000-270700- Mesoscale Precipitation Discussion 0135 NWS Weather Prediction Center College Park MD 1007 PM EDT Sun Mar 26 2023 Areas affected...Central Alabama...Central Georgia Concerning...Heavy rainfall...Flash flooding likely Valid 270200Z - 270700Z SUMMARY...A corridor of intense thunderstorms will continuously track over areas of central AL and central GA tonight where soils are sensitive from recent heavy rainfall. Hourly rainfall rates of 2-2.5"/hr are expected and likely results in localized catastrophic flash flooding tonight. DISCUSSION...Latest HRRR guidance has continued to hone in on the ongoing areas of robust convection stemming from central AL to central GA as the focus for training storms. SPC mesoanalysis shows up to 2,000 J/kg of MUCAPE while PWs are increasing to 1.75". The mean 850-300mb mean flow and bulk effective shear remains parallel to the frontal boundary while the LCL-LFC mean RH values are now at or above 90% saturated. Latest HRRR shows a southwesterly 50 knot LLJ will intersect the front while there is also plenty of strong vertical ascent atop the atmosphere as the region is beneath the right-entrance region of a 140 knot 250mb jet streak. Lastly, there is no shortage of vertical wind shear as SPC mesoanalysis shows 60-70 kts worth of effective bulk shear and 200-300 m2/s2 of effective SRH available to maintain organized strong-to-severe storms into the overnight hours. Look for the developing area of thunderstorms over northern LA and central MS to act as a fire hose, delivering more rounds of strong thunderstorms into central AL and central GA overnight. The prolonged feed of rich low level moisture into and along the frontal boundary, combined with ample instability and organized convection tracking over sensitive soils is the blue print to a potentially dangerous flash flood event. FFGs have steadily dropped from not only this morning's heavy rainfall (which produced 2-5" of rain), but also the initial thunderstorm activity from this afternoon. 1-3hr FFGs are <1.5" in the black outlined area, where thunderstorms will be capable of producing 2"/hr rainfall rates and potentially approach 2.5"/hr in the most intense convection. These locations, as well as poor drainage areas and urbanized communities, are most vulnerable to flash flooding. Given the longevity of this line of storms, expect some roads to be flooded with flowing water over roads in some cases. Flooding on roadways will also be very difficult to identify with the sun now set. Watch for potential flooding in basements as well. The potential for localized catastrophic flash flooding will continue into the overnight hours. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8tjcYEOJoM351RBiep8RAgFQ3_ftkZZSMI9sE-lumu-S1bVxl0aCQxaPKKv3q7yki2Yo= sRF_8gUtTRro-RNWGrpnocM$ for graphic product... ATTN...WFO...BMX...FFC...JAN...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 33548446 33498390 32958375 32378507 31688740=20 31848876 32488886 32978758 33138688 33388573=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) .