FOUS30 KWBC 280758
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
358 AM EDT Sat Sep 28 2024

Day 1
Valid 12Z Sat Sep 28 2024 - 12Z Sun Sep 29 2024

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
OHIO AND TENNESSEE VALLEYS AS WELL AS FOR CENTRAL FLORIDA...

...Ohio/Tennessee Valleys...

The combined upper low and remnant circulation of what is left of
Helene is expected to slow/stall over the Ohio and Tennessee 
Valleys. With very little if any instability to work with the bulk
of rain today will likely be stratiform with hourly rates around  
0.5 inch/hour or lower. At best there may be some isolated flash 
flooding, therefore maintained the broad Marginal Risk that is in
place over the region.

...Florida...

A trailing cold front across the Florida peninsula will be present
during this period along with abundant instability and moisture 
within proximity to this feature. The development of strong
thunderstorms can be expected, especially on the western side of
the peninsula. Recent heavy rain has increased soil sensitivity for
much of the area therefore maintained a Marginal Risk for excessive
rainfall for the western and central peninsula.

Campbell


Day 2 Valid 12Z Sun Sep 29 2024 - 12Z Mon Sep 30 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE MID-ATLANTIC/APPALACHIANS AS WELL AS THE NORTHERN FLORIDA 
PENINSULA...

...Mid-Atlantic/Central Appalachians...

During this period the remnant low of Helene will get picked up by
the upper level jet and track eastward into the Mid-Atlantic and
Central/Northern Appalachians. There will be an increase in
available instability which may lead to localized enhanced rainfall
rates for portions of the Shenandoah Valley and west to the 
Allegheny Front in Maryland, West Virginia, and Virginia; which may
result in isolated to widely scattered instances of flash 
flooding. The level of threat continues to be handled well with the
Marginal Risk that is currently in effect. There may be a need for
a Slight Risk with future updates depending on model trends and
observations.

...Florida...

Convection will continue to fire up in proximity to a stalled
frontal boundary draped across northern/central Florida. Storm
motion may be fast-moving with some tracking over areas hard-hit 
by Helene, but because progressive nature of the convection a 
Marginal Risk remains appropriate for this period.

Campbell


Day 3
Valid 12Z Mon Sep 30 2024 - 12Z Tue Oct 01 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE MID-ATLANTIC/CENTRAL APPALACHIANS...

The lingering upper low over the East and accompanying moisture 
from Helene will continue to produce some showers and thunderstorms
over portions of the Appalachians and Mid-Atlantic into Monday.
Heavy intensity and accumulations are not expected to be widespread
or heavy, however the recent wet period keeps an elevated threat
for excessive rainfall and isolated flooding concerns. A Marginal
remains in effect from south-central Virginia to central 
Pennsylvania.

Campbell
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