Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
759 PM EDT Tue Mar 31 2026

Day 1
Valid 01Z Wed Apr 01 2026 - 12Z Wed Apr 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL NEAR PORTIONS OF
THE GREAT LAKES AND PARTS OF THE NORTHERN MID-ATLANTIC STATES...

Moisture has been funneled in between a trough out West and a mid-
level ridge downstream from the Mississippi River to the eastern
CONUS. Various shortwaves rippling through the Westerlies have led
to thunderstorm activity from the Southern Great Lakes/Midwest into
NY. To the east...convection has been focused between an incoming
front and a pre- frontal outflow boundary near the southern Great
Lakes and southern NY. Convection appears to becoming more elevated
across portions of southern NY ahead of an incoming convective
wave due to an increase in CIN. A total of 2-4" of rain over the
past day or so has made soils more sensitive across southern and
central NY, so maintained the Slight Risk in those areas.

Upstream/to the west, cells have at times aligned across far
northeast IL, northern IN, into northwest OH where 1-3" of rain has
occurred thus far, with other activity from southwest Lower MI
attempting to add to the heavy rainfall as it dives into portions
of northern IN over the next several hours. This is all occurring
ahead of a shortwave currently extending from the Lower Peninsula
of MI across northern IL. Due to ongoing convection and the
possibility of more activity early Wednesday morning as additional
shortwaves move in aloft, made alterations to the dimensions of
the Slight Risk area across OH, IN, and IL, shifting it south
somewhat and extending it farther west. The Marginal Risk was
extended farther to the west- southwest due to a model signal of a
convective uptick across southeast KS which moves across portions
of MO.

Given the ingredients available, hourly amounts up to 1.5" with
additional local totals to 3" are possible from portions of the
Midwest into the Northern Mid-Atlantic states and neighboring areas
of New England into Wednesday morning.

Roth


Day 2
Valid 12Z Wed Apr 01 2026 - 12Z Thu Apr 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL STRETCHING FROM
NORTHEAST KANSAS INTO IOWA...

There continues to be a slight west/northward trend with both the
surface low and overall QPF footprint as a system gets organized
across the Plains during the Day 2 period. A prominent warm-
sector will materialize from west- central Texas into Missouri
with a surface low forecast to be positioned over the Central
Plains by Wednesday afternoon. Several shortwaves will eject
northeast within and ahead of the mean trough leading to multiple
waves of rainfall from the south-central Plains into the Middle
Mississippi Valley. There is increasing agreement for the heaviest
QPF to be located from northeast Kansas into east-central Iowa,
with some training potential, leading to 1-3 inch areal average
amounts in this region, with some potential for isolated higher
amounts of 3+ inches. A slight risk remains for this region, with
a slight north and west shift in the placement consistent with
latest trends, however the area has overall been dry recently which
may limit flood/flash flood potential somewhat. Farther south, a
long axis of convection is expected from Texas to Kansas along the
cold front, but storms in this area should be more progressive and
soils are even more dry than to the north. A marginal risk
continues to be fine for this area. The marginal risk also extends
eastward into the Ohio Valley to account for early period storms
lingering along a stationary front draped across the region.

Santorelli


Day 3
Valid 12Z Thu Apr 02 2026 - 12Z Fri Apr 03 2026

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

By this period the surface low pressure/frontal system will stretch
from the Mid-Atlantic back into the Ohio and Mid-Mississippi
Valleys. Models have trended further north with the overall
precipitation shield, now covering much of the Upper Great
Lakes/Upper Midwest region. The moisture and instability along
with the upper-level support could lead to flooding concerns across
parts of the Great Lakes region. Colder air filtering across the
northern tier will allow for wintry weather concerns in the Great
Lakes to Interior Northeast thus limiting the area where flash
flooding may occur/cause impacts. Some areas could see
transitioning precipitation types throughout the event. A Marginal
Risk area is in effect for portions of southern Wisconsin, Lower
Michigan and northern Illinois where precipitation is most likely
to stay mostly/all rain.

Santorelli/Campbell


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt