Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 13 2023 23:02:30 AWUS01 KWNH 132302 FFGMPD FLZ000-140130- Mesoscale Precipitation Discussion 0185 NWS Weather Prediction Center College Park MD 701 PM EDT Thu Apr 13 2023 Areas affected...South Florida Concerning...Heavy rainfall...Flash flooding possible Valid 132300Z - 140130Z SUMMARY...Low level southwesterly flow intersecting a slow moving outflow boundary is acting as a trigger for thunderstorms this afternoon. This looks to continue for another hour or two, potentially leading to flash flooding. More heavily urbanized spots and poor drainage areas are most at-risk. DISCUSSION...Doppler radar continues to depict re-developing clusters of thunderstorms in the Miami metro area and as far west as the Everglades. The culprit is an outflow boundary that is on the leading edge of a cold pool denoted by a mesohigh on surface analysis between Hollywood and Fort Lauderdale. At low levels, 925-850mb winds are out of the SW, which is intersecting this boundary at a perpendicular angle. This is the cause for billowing convection on the northeast flank of the outflow boundary. SPC mesoanalysis showed MUCAPE of 2,000 J/kg still present, RH values >80% in the LCL-LFC cloud layer, and PWs between 1.7-1.8". The 21Z HRRR still showed a deep warm cloud layer of 11-12 kft in the convection around the Miami metro area as well, suggesting these cells will be efficient rainfall producers for another couple hours. As the outflow boundary pushes south towards Homestead, additional thunderstorms will form and have the ability to produce as much as 2-2.5"/hr rainfall rates. The metropolitan corridor from Homestead, through Miami, and into the Fort Lauderdale area remains very prone to flash flooding after receiving rainfall amounts of 4-8" above normal (higher than that in the Fort Lauderdale area) over the past 7 days. FFGs are as low as 2"/hr neat the Miami metro area, setting the stage for potential flash flooding yet again this evening. As the sun sets, any ponding or flooded roadways will become increasingly difficult for motorists to identify. Storms will finally dissipate once either the outflow boundary (the trigger for the storms) dissipates, or the available instability is exhausted. This should occur within the next couple of hours. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!59Af89sDSoaCVt6wl6lXh90bRdAsV_XfmWkbzWipGehBOtyDMQ3K9XO6-dEeMH4fmSdV= yuWQJprehAleR6_jDVrXjpc$ for graphic product... ATTN...WFO...MFL... ATTN...RFC...SERFC...NWC... LAT...LON 26088045 26038015 25808015 25598026 25498031=20 25478047 25578054 25798058=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) .