Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
349 PM EDT Sun Jun 7 2026
Day 2
Valid 12Z Mon Jun 08 2026 - 12Z Tue Jun 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
MID-MISSISSIPPI, LOWER OHIO, AND TENNESSEE VALLEYS...

On Monday, the northern stream cyclone will move north into
Canada, while the leading shortwave trough and embedded MCV
activity pushes east across the Midwest and Tennessee Valley. At
the same time, a cold front sinking southward along the Carolinas
will drape as a stationary front into the Ohio Valley and Midwest.
Heavy rainfall potential will be focused in the warm sector of the
system over the Mid- Mississippi, lower Ohio, and Tennessee
Valleys where a very moist and unstable air mass will still be in
place. The splitting upper level shortwave will push some energy
across these regions, which will support a broad area of
widespread/numerous thunderstorms. With weakening steering flow and
remnant MCVs from earlier convection, storm motions are expected
to become very slow, which will heighten the threat of flash
flooding.

One of these MCVs may be producing ongoing heavy rainfall across
the Ozarks and into northeast OK and southeast KS at the start of
the Day 2 forecast period Monday morning, which prompted the
upgrade to a Slight Risk here. By midday Monday and into the
evening hours, the flash flooding risk is expected to span from
WI/IL south- southeast to the southern Appalachians and Tennessee
Valley. These numerous slow-moving thunderstorms are forecast to
contain at least 2"/hr rates at times and create scattered
instances of flash flooding. Then, a final round of efficient rain-
producing thunderstorms may occur across the lower Ohio and
Tennessee valleys near the southwest inflow sector of a potent MCV
overnight Monday. Currently, there remains high uncertainty with
the exact location of this feature, but CAMs depict the potential
for 5-7" rainfall totals near western KY and western/middle TN. The
HREF shows impressive neighborhood probabilities (40-60%) of 24-hr
rainfall totals exceeding 5 inches in this region. Some of these
areas within the Slight Risk will also receive heavy rainfall
during the day 1 period, which may increase the risk of flash
flooding if areas are impacted by additional storms with heavy
rainfall on Monday. Isolated pockets of significant impacts are
possible and these areas will be monitored for future upgrades
should confidence in locations of extreme rainfall increase.

Outside of the Slight Risk area, a broad Marginal Risk area extends
into the Upper Midwest and central Plains. Anomalous moisture will
surge north behind the lifting warm front, which will support
locally heavy rainfall that may lead to isolated instances of flash
flooding for the western Great Lakes states. Models have also
started consistently showing a potential MCS forming underneath a
potent upper level shortwave moving quickly east across the central
Plains on Monday evening. Though this feature would likely be
progressive, it could have the potential to produce heavy rainfall
and isolated flash flooding. There is still some uncertainty
regarding the location of this feature, resulting in a broad
Marginal Risk area that will likely be narrowed down over the next
few forecast cycles.

Dolan/Snell

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