Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Oct 07 2024 00:29:44 FOUS30 KWBC 070029 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 829 PM EDT Sun Oct 6 2024 Day 1 Valid 01Z Mon Oct 07 2024 - 12Z Mon Oct 07 2024 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE SOUTHERN TIP OF FLORIDA... Heavy rains continue to be a threat, mostly across southern FL, near a front extending east-southeast from a frontal wave in the Gulf of Mexico. Precipitable water values remain high, near 2.5", ML CAPE up to 2000 J/kg, and effective bulk shear remains around=20 25 kts, which could organize activity. With the 18z HREF risks of=20 3"+, 5"+, and 8"+ as high as they are, left the Moderate Risk level but pared back the Slight Risk area back to southern FL.=20 A=20 Marginal Risk area remains for northeast FL which could have=20 efficient convection overnight in an environment of 500-1000 J/kg, effective bulk shear around 25 kts, and precipitable water values=20 just beyond 2" where the low-level flow is countered by opposing winds aloft. Roth Day 2 Valid 12Z Mon Oct 07 2024 - 12Z Tue Oct 08 2024 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE MIAMI- FORT LAUDERDALE METRO... 21z Update... Moderate Risk added for Miami metro. A weak surface low currently in the eastern Gulf of Mexico likely crosses the southern FL Peninsula late tonight/Monday morning and is likely to provide focus for heavy rain in south Florida through much of Monday. The HRRR, including the recent 18Z run, has been consistent with this more progressive approach with the leading low which seems reasonable and focuses the heaviest swath over the southern end of the FL Peninsula. Given this overlap of southern FL with heavy rain from today, adding the Miami metro to a Moderate is reasonable per request from WFO MFL. As of now it is continued Slight Risks for the Keys where a second day of very heavy rain, which at high tide times may cause flooding due to poor drainage. Consideration was given to a Moderate Risk for the southwest Coast south from Ft Myers which may be necessary how much falls there through tonight. The 18Z HRRR's solution with a farther south southern max tilted the decision toward leaving the southwest Coast in a Slight Risk for now Farther north given the heavy rain from this morning over portions of the Space Coast, the Slight Risk was shifted north to include the rest of the Atlantic coast of the MFL CWA. Wegman/Jackson Day 3 Valid 12Z Tue Oct 08 2024 - 12Z Wed Oct 09 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE FLORIDA PENINSULA... 21Z Update... Slight Risk expanded to include rest of southern Florida Peninsula/Keys. The PRE (predecessor rain event) ahead of Milton will enter its third and final day over the Florida Peninsula on Tuesday. The slower solutions to Milton with 12Z runs today suggest the Tampa Bay area may not see the direct rainfall impacts from Milton until after 12Z Wednesday. Given the inherent uncertainty with the track and persistence of the high PW plume over the Peninsula, the Slight over the Peninsula was maintained again, with expansion over southern FL due to heightened sensitivity there from two days of heavy rain. Predominant southwesterly flow in the trough ahead of Milton's core circulation will retain at least some heavy rainfall. Given the areas of heavy rain through Day 2, soils on the Florida Peninsula at or near saturation, resulting in nearly all of the rainfall converting to runoff. Thus, progressively less rainfall will be needed to result in flooding. Wegman/Jackson Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5vpWcm6gbmhVrHDMV_8qzoEtDWF4u0Bj6q6eEyRIzV5d= N4Jc0z6ueoEmAauXMcVYr64ZP5WANqVtW9XLC0gack-10Lg$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5vpWcm6gbmhVrHDMV_8qzoEtDWF4u0Bj6q6eEyRIzV5d= N4Jc0z6ueoEmAauXMcVYr64ZP5WANqVtW9XLC0gaGEVCH8E$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5vpWcm6gbmhVrHDMV_8qzoEtDWF4u0Bj6q6eEyRIzV5d= N4Jc0z6ueoEmAauXMcVYr64ZP5WANqVtW9XLC0gapTgPHR0$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .