FOUS30 KWBC 150803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
403 AM EDT Wed Apr 15 2026

Day 1
Valid 12Z Wed Apr 15 2026 - 12Z Thu Apr 16 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR THE GREAT=20
LAKES AND NORTHERN OHIO VALLEY..

Showers and thunderstorms will continue to focus near the west-east
orientated frontal boundary draped across the Ohio Valley/Great
Lakes region into the Northeast as a weak surface low traverses the
boundary and intersects the abundant moisture and instability. Meanwhile,
the longwave trough will finally be making progress toward the=20
Central Plains and the deep layer moisture axis and instability=20
shifts slightly eastward. This setup will be conducive for periods
of heavy rainfall. Models are suggesting areal averages of 1 to 3
inches occurring with some overlap with rainfall footprint from
prior days. The Slight Risk remains in effect from northern=20
Illinois to souther Michigan and northwest Ohio to account for=20
uncertainty on storm track and the spread of 2 inch HREF 24 hr QPF=20
neighborhood probability.

...Eastern Oklahoma and the Ozarks...

Convection is expected to become more active during the afternoon
and track generally from the southwest to northeast ahead of the
approaching trough. Eastern Oklahoma into the Ozarks will be in=20
the right entrance of the jet streak, which will help provide lift.
At the surface, high PWATS and surface instability will once again
prime the atmosphere for hourly rainfall rates of an inch/hr. QPF=20
guidance does show a maximum of 1-2 inches across the region, but=20
model guidance shows little to no probability for accumulations=20
exceeding 2 inches. Therefore, a Marginal Risk is maintained for=20
the risk area. Additionally, the more flash flood prone Ozark=20
mountain range is relatively dry.

...Northeast...

Remnants of the storms across the Great Lakes may bring a round of
showers and storms in the morning, followed by another round of=20
heavier showers and thunderstorms in the afternoon. Model guidance=20
shows a corridor of 1-1.5 inches rainfall with embedded higher=20
amounts depending on the model. The relatively lower flash guidance
across western Pennsylvania and the more urban footprint of areas=20
such as Connecticut and New England also help confidence of=20
expanding the Marginal eastward.

Campbell/Wilder


Day 2
Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026

The probability of rainfall exceeding flash flooding guidance is
less than 5 percent.

Campbell


Day 3
Valid 12Z Fri Apr 17 2026 - 12Z Sat Apr 18 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR NORTHERN
MISSOURI, EASTERN IOWA AND NORTHWEST ILLINOIS...

A band of weakening showers and thunderstorms will pass through=20
the Ohio Valley with the lead shortwave trough. Meanwhile the long
wave trough approaching the Midwest will have better large scale=20
ascent and instability to yield better areal coverage of QPF with a
more focused swath of higher amounts across Missouri to the
Illinois/Wisconsin border. The previous Slight Risk area was
positioned more over Iowa and Wisconsin, however the latest trends
suggest a modest south/southeast adjustment to northern Missouri,
eastern Iowa, northwest Illinois and extreme southwest Wisconsin.=20
will be valid from northern Missouri to southwestern Wisconsin for=20

Campbell
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