Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
756 PM EDT Sat Jul 25 2026
Day 2
Valid 12Z Sun Jul 26 2026 - 12Z Mon Jul 27 2026

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL ACROSS THE FOUR
CORNERS REGION...MIDWEST...AND PORTIONS OF THE SOUTHEAST/FLORIDA...

...Four Corners States onto the Central Plains...
Monsoonal flow from the Desert Southwest to the central Rockies
continues into early next week. Above average precipitable water
values and available instability will again support isolated to
widely scattered thunderstorms capable of producing intense rain
rates capable of producing flash flooding. There may be a general
focus for moisture/instability axis to extend farther north than
Saturday, and there is some signal in the CAMs and global guidance
to focus the greatest coverage of heavy rain into western/central
Colorado. Will hold off on any Slight Risk upgrade though due to
uncertainties in the impacts, as well as uncertainties with
instability after an active monsoon Saturday.


...Upper Midwest-Upper Great Lakes-Ohio Valley...
Global, CAM, and AI guidance continue to show convectively-aided
shortwave activity riding down the top side of the upper ridge axis
in northwest flow. A northwest to southeast oriented stationary
front could also provide a convective focus as slightly above
normal PWs but very strong instability come in. However, models
show quite a bit of spread in position of these ridge riders
especially for a short range forecast. The location of convection
will be affected by placement of upper level convergence associated
with a broad arching anticyclonic flow at the jet level. Adjusted
the Marginal Risk to fit with a middle ground model "consensus,"
but it does not cover all the CAM and global model scenarios, so
may need to be adjusted further. Fast movement will be a mitigating
factor for flooding though.


...Southeast into Florida...
Above average moisture will continue to flow into the southeastern
U.S. into a quasi-stationary front with possible waves of low
pressure stretching across Georgia and South Carolina at the base
of an eastern U.S. trough. This front and a surface trough across
Florida should focus the moisture for convection. 90+ percentile
PWs are present along the eastern coast of Florida, where urban
corridors can increase sensitivity to high rainfall rates. A
Marginal Risk covers the threat of isolated flash flooding with
this activity.

Tate/Bann


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