Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 06 2025 08:27:48 FOUS30 KWBC 060826 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 326 AM EST Thu Feb 6 2025 Day 1 Valid 12Z Thu Feb 06 2025 - 12Z Fri Feb 07 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF CALIFORNIA AND THE OHIO VALLEY... ....California... After a one day break another system is forecast to move into CA today and Thursday night. Not an AR but rather a compact, dynamic=20 system with a vigorous mid level shortwave and strong left exit=20 region upper level jet forcing. These dynamics should support a=20 short duration period of enhanced rainfall rates, although the=20 quick forward motion of the system will limit overall rainfall=20 magnitudes. Given the low-level ageostrophic response ahead of the=20 upper level jet streak, the latest (00Z) GEFS output shows a quick=20 uptick in southwesterly 850-700 mb moisture transport, peaking=20 between 3-4 standard deviations above normal across the central 2/3 of CA Thursday afternoon and evening. Recent model runs continue=20 to show 1-2+ inches falling mostly within 12 hours, with localized=20 amounts of 3+ inches over the coastal ranges and Sierra foothills=20 per the latest high-res guidance. Given the saturated conditions=20 and brief potential for higher rates (0.35+ in/hr) beginning around 21Z along the coast and by 00Z farther inland, this may result in=20 localized runoff issues, especially over burn scars across Santa=20 Barbara, Ventura, and Los Angeles counties.=20 ....TN-OH Valleys into the Western Appalachians... Another round of locally heavy rain is expected Thursday across=20 portions of KY, TN, WV and far western VA- NC along and ahead of an approaching cold front. Showers and embedded thunderstorms will be ongoing to start the period (12Z Thu) and may periodically=20 continue through the day/evening near the only slowly southward=20 shifting front. While nothing significant, CAPE upwards of 500-1000 J/Kg still seems likely along this corridor, which should be=20 enough to support locally heavy rainfall rates. While soil=20 conditions and streamflows are returning closer to average after=20 the flooding several days ago, some of this region is still likely=20 more sensitive than normal to additional heavy rainfall. The latest WPC areal-average QPF peaks between 0.75"-1.25", though per the=20 CAMs, localized totals between 2-3"+ are expected, which makes=20 sense given the instability forecast. Overall expect this rainfall=20 to pose a localized flood risk. Hurley Day 2 Valid 12Z Fri Feb 07 2025 - 12Z Sat Feb 08 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 3 Valid 12Z Sat Feb 08 2025 - 12Z Sun Feb 09 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4vunSW8FBHhu_a6Lwa6pKE_JxY_VF8MCF3WyTc9hk8L0= PaVxe2vKPBT8B9X0K7U45N1nrvzpERIWXJZ_UwLL1kGIJTU$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4vunSW8FBHhu_a6Lwa6pKE_JxY_VF8MCF3WyTc9hk8L0= PaVxe2vKPBT8B9X0K7U45N1nrvzpERIWXJZ_UwLLhHnNuow$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4vunSW8FBHhu_a6Lwa6pKE_JxY_VF8MCF3WyTc9hk8L0= PaVxe2vKPBT8B9X0K7U45N1nrvzpERIWXJZ_UwLLX88UgJ8$=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) .