Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Wed Jul 8 2026
Day 2
Valid 12Z Wed Jul 08 2026 - 12Z Thu Jul 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MIDDLE MISSISSIPPI AND LOWER OHIO VALLEYS...

...Middle Mississippi and Lower Ohio Valleys...

Embedded shortwaves rounding the upper-ridge will eventually lead
to deepening troughing across the the Midwest and adjacent areas on
Thursday. The southward shift of stronger flow aloft overtop a
southward progressing cold front will bring broadening scattered
thunderstorm chances from the central Plains east through the
Midwest and into the Lower Great Lakes/Interior Northeast.
Seasonably high moisture and instability ahead of the front will
support the threat for locally heavy downpours and isolated flash
flooding. To the south, a lingering frontal boundary will lift back
northward as a warm front towards the Middle Mississippi/Lower
Ohio Valleys ahead of the approaching cold front, helping to focus
storm development through this corridor. Embedded waves locally
slowing the progression of the cold front as well as generally mean
westerly flow over the west-to-east oriented boundary will promote
potential repeated/training storms, increasing rainfall totals.
The most recent deterministic global and hi-res guidance have shown
an increasing potential for multi-inch rainfall totals, with the
AI guidance also favoring a heavier rainfall axis through this
corridor. For these reasons, a Slight Risk has been introduced with
this outlook.

...Mid-Atlantic...

Further east, some of the 00Z hi-res guidance now stretching at
least partially into the day 2 period is rather bullish on locally
heavy rainfall across the Mid-Atlantic with totals of 2-3"+. An
embedded upper-level shortwave and accompanying surface wave along
the lingering southern frontal boundary could lead to more
widespread thunderstorms through this region with plentiful
moisture to support heavy rainfall. For now, have extended the
Marginal Risk eastward to cover this region, but another embedded
Slight Risk may be needed with more confidence in this scenario.

...Central High Plains...

A familiar set-up will remain in place Thursday as a frontal
boundary becomes quasi-stationary through the region. Moist/post-
frontal upslope flow and convergence along the boundary will
continue to support storms with locally heavy downpours and an
isolated risk for flash flooding.

Putnam


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