Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Mar 26 2026
Day 1
Valid 12Z Thu Mar 26 2026 - 12Z Fri Mar 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE MIDWEST THROUGH PORTIONS OF THE CENTRAL AND NORTHERN
APPALACHIANS...

A strong cold front tracking south out of the Great Lakes and
Canada will provide the primary forcing for a line consisting of
several segments of severe thunderstorms this evening through the
overnight period. Working against flash flooding remains the very
fast movement of any individual cells of heavy rain, the
progressive southward movement of the cold front, average soil
moisture (which usually can stand to soak in lots of rain before
the rest converts to runoff), and average PWATs (around 1.25
inches) and instability (between 1,000 and 1,500 J/kg of MUCAPE).
Working for flash flooding is the several urban areas which locally
lower FFGs and have more flood-prone areas, good potential for
training storms, and into portions of southwest Pennsylvania,
upslope potential against the mountains. Into Illinois, ongoing
slow moving showers and storms are locally saturating soils in
east-central portions of the state and into western Indiana.
Rainfall forecast amounts have increased a bit across Ohio and
southwest Pennsylvania. This moves the threat up into the higher-
end Marginal risk category (10-15% chance of exceeding Flash Flood
Guidance). Thus, any further increases in the rainfall amounts may
require a targeted Slight later today anywhere from Illinois to
southwest Pennsylvania, generally along I-70.

Wegman

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