Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
858 PM EDT Fri Aug 8 2025
Day 1
Valid 01Z Sat Aug 09 2025 - 12Z Sat Aug 09 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
NORTHERN MINNESOTA INTO FAR NORTHWESTERN WISCONSIN...

01Z Update...
Awaiting the initiation of the next MCS across portions of the
Upper Midwest near or just east of the ND/MN border, and rapidly
progress east in very similar fashion to the behavior of the
MCS earlier this morning. The MCS is likely to take the form of a
squall line, and therefore be a minimal flooding threat, despite
the storms having ample deep-layered moisture (up to 3 sigma above
normal) climatology to work with and precipitable water values
approaching 2 inches. The primary flooding concern remains where
any storms get hung up on the southern end of the line, resulting
in localized training. If this does occur, then the southern
portion of the Slight along the MN/WI border would have the highest
flash flooding risk. The 18Z HREF largely supported placement of
the previously-issued Slight Risk area and the surrounding
Marginal Risk area. The past couple

Farther south, the Marginal risk area was pulled south to cover
much of Iowa and a portion of eastern Nebraska where the latest
runs of the HRRR have been supporting the 18Z NAM nest idea of
convection with potential for some intense rain rates building
farther south and east than suggested by the HREF...although the
NAM nest maximum may be too high.

...Southeast...
Maintained the Marginal risk area over coastal portions of South
Carolina and Georgia into the northeast corner of Florida given
persistence of on-shore flow and the lingering cyclonic energy in
the low levels just off shore. A downward trend should continue
along the west coast of the Florida peninsula so that portion of
the state was removed from the Marginal risk area.

Bann


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