Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
832 PM EDT Mon Jun 29 2026
Day 2
Valid 12Z Tue Jun 30 2026 - 12Z Wed Jul 01 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE GREAT LAKES...NEW ENGLAND...OVER SOUTHWEST TEXAS AND THE
FLORIDA PENINSULA...

...Southern High Plains to the Great Lakes...

There will be a risk of excessive rainfall in many of the same
places as on Day 1 as a deep/strong low moves slowly from
Saskatchewan to Manitoba while a broad, sprawling upper high
expands across the Southern Plains into the Mid-Atlantic and parts
of the Northeast United States. This results in broad southwesterly
flow that transports Gulf moisture into parts of the Southern High
Plains northeastward through the Great Lakes. Embedded shortwave
energy within the flow will support increasingly scattered
convection in this anomalously moist airmass, with locally heavy
rains and isolated runoff issues. The concern is especially
heightened over burn scars and dry washes/arroyos of the terrain
near the southern Rockies. The latest hi-res guidance shows the
potential for 1-3"+ of rainfall with these storms even if they
remain rather short-lived and transient due to efficient downpours
with rain rates of 1-2" per hour.

...New England...

The latest hi-res guidance supports the maintenance/renewed
development of thunderstorms in northwesterly flow over New England
and portions of Upstate New York, possibly even tied all the way
back to ongoing thunderstorms this (Monday) afternoon. The more
widespread/organized nature of the convection would bring at least
the risk of isolated flash flooding with storm total rainfall of
2-4" possible as suggested by much of the hi-res guidance.
Additional refinement and possible upgrade to the risk area may be
necessary with more confidence in this scenario depending on the
evolution of ongoing convection through the overnight hours.

...Florida...

A cold front will be the focus for showers and thunderstorms as it
makes its way southward into the northern Florida peninsula. There
has been an increasing signal in the models for convection and the
storms look to be efficient rainfall producers considering able to
tap precipitable water values around 2 inches so added a Marginal
risk has been outlined. The chance of showers and thunderstorms
pushes westward in conjunction with the front and kept the risk
closest to the Gulf coast.

Putnam/Bann


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