Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
820 PM EDT Wed Jul 1 2026
Day 2
Valid 12Z Thu Jul 02 2026 - 12Z Fri Jul 03 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
UPPER MIDWEST...

Northern Plains/Upper Midwest/Great Lakes...

20Z Update: The overall synoptic pattern forecast across the
Northern Plains to Midwest remains steadfast with the 12z suite
maintaining a solid run-to-run continuity in both the mid-level
vorticity advection regime and alignment of the 500mb height field.
The consistency has allowed for a maintenance of the previous
forecast with some expansion to the west over SD and southern ND to
reflect the trends within the CAMs and ensemble bias corrected QPF
output indicating heavy precip initiating upstream a bit further
than previously modeled. Environmental conditions are ripe for a
long axis of heavy rain potential thanks to a deep moist profile
situated over the northern fringes of a broad ridge to the south
and the alignment of a well-defined quasi-stationary front forecast
to bisect the Northern Plains to Midwest during the period. Flow
aloft will run parallel to the front leading to the prospect of
training convection anchored within proximity to the front, mainly
within a pronounced theta_E gradient over the region. HREF
neighborhood probabilities for >2" of rainfall are within the
40-70% range extending from Bismarck, ND to points southeast with
an eastern inflection to Milwaukee, WI. Some of the areas within
this zone are bound to see a multi-day impact from convection which
will benefit lower FFG's that could spur trouble with the incoming
wave of heavy convection forecast Thursday evening. Considering
models remaining relatively consistent on the signal, the previous
SLGT risk was maintained with that aforementioned expansion to the
west based on the latest QPF and correlated probability trends for
greater than 2 and 3-inch thresholds.

Kleebauer

..Previous Discussion..

Models maintain a general convective threat across much of the
Upper Midwest into the far western Great Lakes region on Thursday
as the synoptic pattern continues to promote persistent
northwesterly flow around the northern periphery of a strengthening
upper ridge positioned across the Eastern U.S. The general area of
convection from the Dakotas southwestward into parts of Iowa and
Wisconsin. The threat for isolated instances of flash flooding as
models have QPF maxima littered across this axis. There could be
an instance where heavy rainfall intersects areas hit the previous
period and offer a better opportunity for flash flooding, however
judgment on any targeted upgrades would need to be assessed after
the previous period's rainfall. Given that and some of the QPF
totals from the higher resolution guidance, did opt for a Slight
Risk area.

Bann

West Texas...

20Z Update: No changes necessary in this update for the area of
west TX up through portions of the Southern High Plains with the
greatest potential likely to reside over southwest TX with
diurnally driven convection over the terrain (Davis Mountains and
adjacent Stockton Plateau). High probabilities (50-80%) for
locally >2" exist over both areas, especially the Davis Mountains
where the combination of strong surface based destabilization and
elevated boundary layer moisture will likely correlate to
thunderstorm initiation after 18z Thursday. The previous MRGL risk
was maintained as a result.

Kleebauer

..Previous Discussion..

Models depict another another round of isolated to widely scattered
thunderstorms during the late day and evening convection across
West Texas and a small portion of neighboring states on Thursday.
The RAP depicts MUCAPE values peaking over 2500 J per kg which
should help support locally intense rainfall rates.

Bann


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