Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Nov 17 2023 04:23:27 AWUS01 KWNH 170423 FFGMPD FLZ000-170830- Mesoscale Precipitation Discussion 1177 NWS Weather Prediction Center College Park MD 1122 PM EST Thu Nov 16 2023 Areas affected...east-central FL Peninsula Concerning...Heavy rainfall...Flash flooding likely Valid 170415Z - 170830Z SUMMARY...Slow moving cells will continue a threat for locally extreme rainfall rates and significant to potentially life-threatening flash flooding across portions of the east-central FL Peninsula. Rainfall rates of 2-3 in/hr along with highly localized rates in excess of 4 in/hr are expected to continue through 08Z. DISCUSSION...Radar imagery at 0345Z showed the slow moving cell that has impacted the I-95 corridor from near Fellsmere to just west of St. Lucie has increased forward speed in the last 30 minutes, from near 6 kt to ~9 kt along with a turn toward the east. However, MRMS-derived rainfall rates were still 3 to 4+ in/hr along the Indian River/St. Lucie county line, albeit lower than the 5+ in/hr estimated via MRMS and confirmed via the Wunderground network prior to 03Z. Farther north, cells along a north-south orientation have slowed over the past 1-2 hours with hourly rainfall totals approaching 4 in/hr via MRMS to the immediate east of the Orlando/Kissimmee metro region. Moderately strong near surface to 850 mb easterly winds of 25-45 kt along the Treasure and Space coasts continued to support a strong low level convergence axis just inland of the coast along with sufficient shear for mesocyclone formation supported by the advection of 500-1500 J/kg MLCAPE from the east. In addition to broader scale lift ahead of a mid-upper level trough over the eastern Gulf of Mexico, upper level divergence within the left-exit region of a 100 kt jet max over southern FL was also contributing to lift across the region. The cell currently over St. Lucie County is expected to continue following Bunkers-right motion which backs toward the west with southward extent and time over Indian River and St. Lucie counties. Further weakening is expected as the cell moves away from the better low level convergence/stronger low level easterly flow observed with southward extent and as the offshore low level circulation translates northward. Farther to the north, the threat for slow moving, high to extreme rainfall rates will continue to affect portions of the east-central Peninsula given continued parameters supporting lift will maintain over the next few hours, especially from the Indian River/St. Lucie county line to Volusia County and points westward, up to about 50 miles from the coast. While the potential for heavy rain will remain localized, overlap with any urban areas could result in additional significant to potentially life-threatening flash flooding. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7uVrZC7xfPqFLqGdL-nFpx_m933TT7jjJSUAFECw8SH2zW3-WMqjXIH-fsziEs3WA7XR= A2KCXx-ILq32FU5VsPajfXg$ for graphic product... ATTN...WFO...MLB...TBW... ATTN...RFC...SERFC...NWC... LAT...LON 29218103 28808048 27297997 27028033 27108076=20 27368102 27748126 28248142 28678153 29038143=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) .