Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 14 2023 16:16:26 AWUS01 KWNH 141616 FFGMPD FLZ000-142215- Mesoscale Precipitation Discussion 1170 NWS Weather Prediction Center College Park MD 1115 AM EST Tue Nov 14 2023 Areas affected...Southeast Florida... Concerning...Heavy rainfall...Flash flooding possible Valid 141615Z - 142215Z SUMMARY...A narrow band of thunderstorms with capability of intense short-term rates (2-2.5"/hr) may orient favorably for repeating/training through urban corridor posing possible localized rapid inundation flooding. DISCUSSION...GOES-E visible imagery denotes shower activity starting to increase across the northeastern Florida Strait toward across to Grand Bahama and Abaco. A weak boundary layer wave developed from the laminar flow parallel to the island and surface to boundary layer winds have responded with increased convergence along and north of the stationary front from Key Largo to Andros Island. Moisture has pooled along the northern edge of the boundary and CIRA LPW indicates moisture has also pooled upstream through the Bahamas with .6-.7" noted over Abaco moving quickly east. Combined with the 1-1.2 in the lowest levels, total PWat is nearing 2" with deep warm cloud layer for efficient rainfall production potential through the afternoon into the evening. While the surface front is starting to angle northward in the eastern Gulf of Mexico, a weak inverted surface trof supports some backed surface low across the southern peninsula...and recent slight veering was noted along the Miami-Dade coastal stations suggesting increased moisture flux convergence is starting to occur with strengthening easterly flow to 15kts expected as the aforementioned boundary layer wave continues to move west-northwest in the next hour or so. The limiting factor has been and will continue to be sufficient heating and instability for stronger vertical development. Recent hi-res rapidly refresh guidance continues to suggest heating into the low to mid-80s supporting SBCAPEs of 1500-2000 J/kg. Given moisture, convergence environment, efficient 2-2.5"/hr rates will become possible given the vigor of the updrafts.=20 Currently, there is solid signal for Bahamian streamer Cu to remain fairly unidirectional through depth to support an axis likely between S Palm Beach county to N Miami-Dade county for potential repeating cells maximized with along the convergence axis. Combined with deep layer bulk shear over 35-40kts, organization of the line and slowing forward speeds (potential backbuilding) may aid rainfall duration at any given point along the training axis. 12z HREF probs have increased in line with current observational trends, with 1"/hr rates starting around 17-18z and maximizing over 80% by 19-20z. 2"/hr rates nearly reach 50% with even some hint of 3"/hr rates at 25% around 21-22z. As such, there is solid signal of 5"+ near 45% by 00z over this axis. Given the higher probability of rates and signal of totals...storm scale interaction will still determine specific axis/locations within the MPD area of concern but flooding will most certainly be due to hydrophobic and poor/flat drainage in and around urban centers with this axis. So all considered, flash or rapid inundation flooding is considered possible into this afternoon. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7S46kNWTd5bgT6JVxphaDg0fCaCdO4mNjR-V9_YhVAFsAtmYzeDYeqMWTPxdEn3C3X51= yUfTVbg0qJqtNjOPGbtDCSc$ for graphic product... ATTN...WFO...MFL...MLB... ATTN...RFC...SERFC...NWC... LAT...LON 27078021 27008002 26617996 26187999 25768005=20 25668022 25848055 26088079 26498097 26898061=20 27038045=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) .