FOUS30 KWBC 020806
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Thu Apr 2 2026

Day 1
Valid 12Z Thu Apr 02 2026 - 12Z Fri Apr 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN ILLINOIS, WISCONSIN AND MICHIGAN...

The primary area of interest for flash flooding will likely lie
over far northern Chicago suburbs up into the Milwaukee metro due
to the areal urban footprint and suggestion of heavier rainfall in
the area, especially the second round of convection. Fortunately,
rates are generally capped at 1-1.25"/hr at peak intensity with
much of the CAMs hourly outputs closer to 0.5-1"/hr for the
heaviest periods of impact. This lies right on the edge of any FFG
exceedance, so the threat will be somewhat capped overall for a
multitude of reasons. There will likely be two main rounds- the
first in the morning hours followed by a most robust line during
the afternoon when there will be more ample large scale
forcing/instability as the surface cold front approaches from the
West. Overall areal averages across the region will be in the 1-2
inch range with locally isolated higher amounts possible.

Campbell/Kleebauer


Day 2
Valid 12Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS REGION...

Strong to severe thunderstorms along with embedded heavy rainfall
will track across the Southern/Central Plains into the Mississippi Valley/Midwest during this period. Moisture (with PWs over the
90th, perhaps 95th percentile) and instability are likely to pool
along and ahead of the associated cold front and produce widespread
convection. Storms likely beginning in the afternoon are expected
to get reinforced through the evening and night hours as a low
level jet picks up ahead of the cold front. Given that some of this
region has been drier, it will take awhile before there are
substantial flash flood concerns. Some of the highest amounts/rates
are likely to focus over parts of central and eastern Oklahoma
down into the Red River Basin between the Texas and Oklahoma
border. Consensus has areal averages of 1 to 3 inches while some of
the hi-res guidance is hinting at isolated maximums of 4 to 7
inches. Slight Risk area spans from north-central Texas to
southwest-southern Missouri.

Campbell/Kleebauer


Day 3
Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
AND EASTERN GREAT LAKES SOUTHWESTWARD TO CENTRAL TEXAS AND THE
LOWER MISSISSIPPI RIVER VALLEY...

Much of the convection that evolves across the Marginal Risk area
on D3/Sat will depend on specific evolution of convective complexes
that originate from the central/southern Plains on D2/Fri. Although
those details are a bit uncertain at the time frame, general
consensus is that one or two MCSs will traverse the Mississippi Valley/Mid-South early in the forecast period before convective
redevelopment occurs upstream along a composite outflow/cold front
during peak heating hours from central Texas to Mississippi. Areas
of training are likely if this pattern holds, with initiating
boundaries supporting deep convection eventually becoming more
parallel to steering flow aloft. Portions of this region may
require an upgrade to Slight in later outlook updates.

Farther north, convective coverage is far less certain -
particularly from Illinois to Ohio. Deeper convection south of
these areas could disrupt inflow/instability and lead to a minimum
in precipitation in these areas. Again - this regime is uncertain.

The primary reason Marginal was maintained for D3 from Illinois
eastward to New York State and West Virginia was soils/local
sensitivity. Soils are wetter with eastern extent from prior
rainfall and could still be sensitive to even moderate rainfall by
D3/Sat in a few spots.

Cook
$$
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* Origin: Project Scorpio TEST (618:250/6)