Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 29 2024 08:16:13 FOUS30 KWBC 290815 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 415 AM EDT Sun Sep 29 2024 Day 1 Valid 12Z Sun Sep 29 2024 - 12Z Mon Sep 30 2024 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE INTERIOR MID-ATLANTIC... ....Mid-Atlantic/Central Appalachians... Remnant moisture from Helene will remain caught up in the upper=20 trough pattern across the Ohio Valley while the mean trough begins=20 to slowly advance eastward through the period. During this period precipitable water anomalies will be on the order of 1 to 2=20 standard deviations above normal and will encounter increased=20 forcing from the upper jet and modest lift through the column over=20 much of the Mid-Atlantic. This setup will support the development=20 of scattered to numerous thunderstorms that will likely have slower storm motions. Recent rains have lowered local FFGs and increased=20 sensitivity across the region. Areal average QPF for the region=20 will be in the 1 to 3 inch range with isolated maximums in excess=20 of 3 inches will be possible. A Slight Risk for excessive rainfall=20 is in effect for extreme western Maryland, eastern West Virginia,=20 northern/central/south-central Virginia and north-central North=20 Carolina. A Marginal Risk area spans from northeast=20 Georgia/northwest South Carolina to southern Pennsylvania and=20 southeast Ohio. ....Florida... An unstable airmass coupled with lingering deep layer moisture=20 will promote isolated to widely scattered thunderstorm activity=20 capable of localized flooding, especially within urbanized zones. Any of these storms will have the capability to produce 2 to 4 inches, especially along the coastline. A Marginal Risk for excessive rainfall is in effect for central portions of the peninsula. Campbell Day 2 Valid 12Z Mon Sep 30 2024 - 12Z Tue Oct 01 2024 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF=20 THE INTERIOR MID-ATLANTIC... High pressure to the north, and a developing surface reflection=20 off the Mid-Atlantic coast thanks to the upstream trough will=20 create a persistent northeasterly flow setup with greater upslope=20 emphasis within the terrain across Western Virginia into the=20 far eastern West Virginia. There will be an enhancement of forcing through the column of atmosphere near the Appalachian/Blue Ridge=20 spine that may result in hourly rainfall rates of 1 to 1.5=20 inches/hour during this period. Soils near saturation from recent=20 rains will keep the threat for flash flooding elevated for much of=20 this region thus maintained a Slight Risk for excessive rainfall=20 for extreme south-central Pennsylvania, western Maryland, eastern=20 West Virginia and northern/central Virginia. A Marginal Risk area=20 spans from northeast Tennessee/northwest North Carolina to southern Pennsylvania. Campbell Day 3 Valid 12Z Tue Oct 01 2024 - 12Z Wed Oct 02 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9QpjW14xm-iiPji1v9_EZVRjQjk4Udistk-jofZv7m9h= tf9Ck72zvGKXv69N8UCXwNZOj1aHsaOLHYkB71wEqdUgQzU$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9QpjW14xm-iiPji1v9_EZVRjQjk4Udistk-jofZv7m9h= tf9Ck72zvGKXv69N8UCXwNZOj1aHsaOLHYkB71wE_XxAJ9M$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9QpjW14xm-iiPji1v9_EZVRjQjk4Udistk-jofZv7m9h= tf9Ck72zvGKXv69N8UCXwNZOj1aHsaOLHYkB71wE22nqKKU$=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) .