FOUS30 KWBC 310757
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
357 AM EDT Tue Mar 31 2026

Day 1
Valid 12Z Tue Mar 31 2026 - 12Z Wed Apr 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS 
WESTERN NEW YORK AND SOUTHEAST MICHIGAN...

Overall upper pattern will become slowly backed as a deep longwave
trough out west begins to pump the mid-level ridge downstream from
the Mississippi River to the eastern CONUS. At the surface, a 
quasi-stationary front will bisect areas west to east from the 
Midwest the Northeast with a weak surface low migrating along the 
frontal positioning. Shortwave associated with the area of low 
pressure will eject through the Great Lakes leading to a period of 
convective development downstream into Michigan and points east.
This initial round is expected to occur early in the period,
producing moderate to locally heavy amounts across southeast
Michigan and to the favored downwind locations of Lake Erie. The
extra enhancement from Lake Erie should boost rainfall closer to 2 inches.

As the morning progresses, the low will migrate into Ontario and
the frontal boundary will drop southward toward the Ohio Valley. A
second shortwave is set to eject and usher in another round of
convection for the northern Missouri Valley. PW values will be
increasing which should boost rainfall rates to 1-1.5 inches/hour.
These two rounds of heavy rain for western New York areas downwind
of Lake Erie will see widespread totals of 1.5-3" leading to a 
more elevated flash flood concerns, especially when combined with 
river flood concerns as stream flows across the region have been 
elevated since the previous events over the area. Flood Watches 
will be in effect for portions of western NY given the signal of 
both the river and flash flood threat aligning well with a targeted
SLGT risk across the area.

The Slight Risk extends back into Detroit due to the urbanization 
factors and expected heavy rainfall the front half the period into
the metro which creates a better opportunity for flash flooding 
considering the setup. A Marginal Risk encompasses the 
northeastern portion of Illinois through southern Michigan, 
northern Indiana/Ohio, and extends well east and northeast to 
include Upstate New York, Northern New England, and the northern 
Hudson Valley as combination rainfall and snow melt will allow for 
elevated stream flows and any locally heavy rainfall could induce 
flash flood prospects.

Campbell/Kleebauer


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

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

The latest guidance continued to trend westward with the overall QPF
footprint however maintained consensus for the heaviest amounts to
focus from eastern Kansas to the Missouri/Iowa border. A long axis
of convection is expected from Texas into the Mid/Upper Mississippi
Valley. 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 across parts of Kansas 
into Missouri. Multiple waves of heavier rain could impact the 
area. Despite the antecedent dry conditions in place, prolonged 
rainfall within the urban corridor with slower cell motions could 
lead to a greater threat for scattered flash flooding before the 
system finally moves eastward and the area sees the frontal 
passage. Areal averages of 1.5-2.5 inches are forecast however
there is potential for isolated higher amounts of 3+ inches. A
Marginal Risk area spans from central Texas to the Illinois/Indiana
border. A Slight Risk area was hoisted for eastern Kansas,
western/northern Missouri and southeast Iowa.

Campbell/Kleebauer


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. A swath of potentially impactful
freezing rain/ice along with multiple inches of April snow, with 
the heaviest snow currently forecast in the U.P. of Michigan into 
northern Maine. 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.

Campbell
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