Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
401 PM EDT Wed Jul 29 2026
Day 1
Valid 16Z Wed Jul 29 2026 - 12Z Thu Jul 30 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE
BERKSHIRES AND SURROUNDING AREAS...

...16Z Update...

The Moderate Risk was trimmed from the east across central
Massachusetts and eastern Connecticut with this update. While rain
is ongoing in most of these areas, the area didn't see anywhere
near as much rain as areas further west from the Berkshires to the
Hudson Valley, so the area remains in a Slight.

The Marginal and Slight risk areas were trimmed on the southern end
along Long Island Sound (including NYC), as the steadiest rains in
that area have ended. Scattered showers can't be ruled out, but
even in urban areas should not produce enough rain to cause even
isolated flash flooding.

Minor tweaks were made to other portions of the Northeast.

Out west, the Marginal Risk was extended northwest to include the
Missouri River valley in eastern Nebraska and Kansas, as well as
western Iowa and Missouri, including the KC Metro. This is
primarily for heavy but slow moving storms that have developed in
this area from an overnight MCS.

Finally, the Slight Risk in Colorado was expanded south to include
the extreme northeastern fringe of New Mexico, where afternoon
showers and thunderstorms that will be at least initially tied to
the terrain may cause widely scattered instances of flash flooding.

Wegman

...Previous Discussion...

...Northeast...
Intense rainfall will be on-going over portions of the Northeast as
the Day 1 period begins at 29/12Z, with some training of cells and
some places experiencing multiple rounds of heavy rainfall--particularly
across western Massachusetts, far southern Vermont, and broadly
across southern New England. Rainfall rates between 1-2"/hr at
times will be possible through late morning/early afternoon and
totals of 2-4" (with localized higher amounts possible) are
expected.

HREF/RRFS neighborhood probabilities from the 29/00Z runs remained
high (greater than 80 percent) for 3" totals across
western/central MA into far southern VT. Probabilities are moderate
(30-50 percent) for 5" totals.

Given the setup and risk of significant flash flooding continuing
from the day 1 period, a Moderate Risk was maintained with few
changes given the cumulative rainfall amounts. After 30/00Z...the
intensity of rainfall should subside while also shifting eastward.

...Four Corners States into the Central/Northern Plains...
Monsoonal flow persists with isolated to widely scattered
convection extending from the Four Corners region northward and
eastward...perhaps extending as far east as the plains of Colorado.
Some of this rain could fall atop soils saturated from heavy rain
prior to the start of the Day 1 period at 29/12Z. Persistence in
the pattern and moisture distribution leaves the risk area in good
shape with the Slight Risk focused on eastern Colorado.

...Central Gulf Coast Region into parts of the Southeast...
A cold front stalling along the Gulf Coast will be a focus for slow
moving and training thunderstorms today into tonight. Guidance
continues to indicate a low-probability threat for at least 3" of
rain due to training of 1-2"/hr rain rates within favorable
thermodynamics. This region can generally tolerate significant rain
rates and this amount of rainfall, but any more pronounced
training could result in isolated flash flood related impacts.

Taylor/Bann


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