Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
933 PM EDT Wed Jun 10 2026
Day 2
Valid 12Z Thu Jun 11 2026 - 12Z Fri Jun 12 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
MIDWEST...

...Southern Plains to Midwest...
The frontal wave that develops over the central Plains Wednesday
night will surge northeast and intensify as a strong trough swings
across the north-central United States. Strong southerly flow ahead
of this wave will drive an anomalously moist and highly unstable
air mass into the Midwest that will support enhanced convection in
the vicinity of the frontal wave. Showers and storms will also form
along the frontal boundary as it progresses, extending back into
the southern Plains, but the progressive nature of the front should
somewhat limit the flash flood potential over the Plains. Moisture
will pool ahead of the cold front as it surges southeastward,
creating a swath of high PWAT values of 2-2.5 inches from the
southern Plains to the Great Lakes that will support high rainfall
rates in excess of 2 inches per hour. Available CAMs and global
models show a broad area of heavy rainfall across the Midwest,
which is encompassed by a Slight Risk of excessive rainfall, and
the highest rainfall totals are expected to focus over eastern
Iowa, northern Illinois, and southern Wisconsin. A heavy
rainfall/flash flood threat expected Wednesday evening/in the Day 1
period across this same region will make this area more
susceptible to flash flooding in the Day 2/Thursday period. For
now, maintaining a higher end slight risk, though an upgrade to a
moderate risk in future issuances is not out of the question and
very much dependent on what materializes across this region
Wednesday evening. A larger Marginal Risk area stretches from the
Midwest to the southern Plains where heavy rain may lead to
isolated instances of flash flooding.

...Central Appalachians and Northeast...
An upper level shortwave trough is forecast to move southeast
over the Ohio Valley, Northeast, central Appalachians, and Mid-
Atlantic, which will trigger another round of scattered showers and
thunderstorms on Thursday. An anomalously warm and moist air mass
will be in place across these regions, with PWAT values of 1.75-2
inches, which will support rainfall rates of 1-2 inches per hour.
The upper level shortwave will result in an increasingly sheared
environment over the Northeast Thursday afternoon, which will allow
for some organized convection with higher rainfall rates in excess
of 2 inches per hour. These storms should move quickly, but
intense rainfall rates will support a risk of at least isolated
instances of flash flooding for portions of eastern Pennsylvania,
northern New Jersey, southern/central New York, and Connecticut
where a Marginal Risk of excessive rainfall continues. Another
Marginal Risk area remains in place over the central Appalachians
from West Virginia into southwestern Pennsylvania where persistent
northwesterly upslope flow will support enhanced precipitation
chances in this area. Soils will be somewhat saturated from
rainfall expected in the Day 1 period, and isolated flooding
concerns may continue into Thursday with showers and storms capable
of producing rainfall rates of 1-2 inches per hour.

...Southwest Florida...
The pattern remains favorable in the Day 2/Thursday period for
colliding Atlantic/Gulf sea breezes within a deep moisture flow.
PWAT values in excess of 2 inches, along with sufficient
instability, will support convection capable of producing heavy
rainfall. This will be a quite localized threat, with flash flood
potential focused over the mainly urban areas. With a similar
setup expected in the Day 1 period, went ahead and introduced a
Marginal Risk across Southwest Florida.
Dolan/Santorelli


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