FOUS30 KWBC 280037

QPFERD



Excessive Rainfall Discussion

NWS Weather Prediction Center College Park MD

837 PM EDT Mon Oct 27 2025



Day 1

Valid 01Z Tue Oct 28 2025 - 12Z Tue Oct 28 2025



...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS

OF SOUTHERN FLORIDA...



Existing showers and thunderstorms are moving slowly southeast as

CIN tries to set in, which is leading to some reduction in 

intensity ahead of the main line crossing Lake Okeechobee into the

southern peninsula. Since some degree of cell training and cell mergers

remain possible, reconfigured the Marginal Risk to account for the

minimal threat. The mesoscale guidance suggests that activity 

could persist as late as midnight before fading. Until then, hourly

amounts to 2" and local totals to 4" remain possible.





Day 2

Valid 12Z Tue Oct 28 2025 - 12Z Wed Oct 29 2025



The probability of rainfall exceeding flash flood guidance is less

than 5 percent.



2030z Update: An inherited MRGL risk centered on the Mid-South was

removed for this update, as a lack of instability and prevailing

drought conditions are expected to result in largely beneficial

rainfall for the region (as suggested by less than 5% chances for

1-hr, 3-hr, and 6-hr FFG exceedance per latest 12z HREF suite).



Churchill





Day 3

Valid 12Z Wed Oct 29 2025 - 12Z Thu Oct 30 2025



...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE

SOUTHERN AND CENTRAL APPALACHIANS AND SURROUNDING PORTIONS OF THE

OHIO/TENNESSEE VALLEYS...



2030z Update: A closed upper-low will pivot from the Mid-South to

the OH Valley, causing rainfall to overspread the TN/OH Valley with

anomalous low- level moisture transport driving east-southeast

moisture transport into the Southern/Central Appalachians. While

the bulk of this rainfall is expected to be beneficial, short-term

FFGs (1-hr and 3-hr) may be low enough (as low as 1.0" and 1.5",

respectively) to allow for localized exceedance across the region.

This is despite limited instability (similar to Day 2 across the

Mid-South), as the dynamics of the closed low (notable PV anomaly

with enhanced divergence aloft via left exit region of ~130 kt jet

streak @ 250 mb) may result in localized 2" exceedance in the OH/TN

Valley (with terrain forcing primarily driving any localized 2"

exceedance along/east of the Southern/Central Appalachians).



Churchill





Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt