Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
859 PM EDT Fri Jul 3 2026
Day 2
Valid 12Z Sat Jul 04 2026 - 12Z Sun Jul 05 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER SOUTHEAST
KANSAS INTO NORTHEAST OKLAHOMA...

...Kansas into Oklahoma...

20Z Update: Increasing confidence in the generation of an MCS
across the Central Plains, moving southeast into the Lower
Mississippi Valley Saturday evening in conjunction with a cold
front approach from the north and surface low positioned over the
adjacent Southern Plains. Both hi-res and global deterministic have
a signal for convective initiation after 00z Saturday over KS with
upscale growth anticipated downstream of any cell clusters that
materialize as they move into a budding LLJ. This is a fairly
typical signal for such a synoptic pattern with increasing low-
level convergence ahead of an approaching cold front. Low-level
flow will become backed for a time across the area of southeast KS
into northeastern OK ahead of the front according to forecast
soundings from various deterministic CAMs. This leads to effective
boundary layer shear approaching 35-40kts will be efficient in
sustaining stronger updrafts and mesocyclone formations capable of
strong to severe cells, even in the case of cell mergers. PWATs
between 1.8-2.1" are expected in the area of interest allowing for
a deep moist profiles suitable for heavy rain cores. HREF probs for
>1"/hr rates are actually prolonged within the temporal aspect of
the forecast over the region with a solid 30-50% prob from 00z-12z
Saturday across the aforementioned area meaning some back-building
behind any organized convective pattern is plausible. Modest 30-50%
probs for >3" exist over the area from I-70 west of Kansas City
down through Tulsa with the highest probs located over northeast
OK. Isolated low-end probs for >5" also exist, but are generally
noting the top-end of the potential for the threat as the
progression of the MCS should limit the prospect for more
appreciable impacts/coverage.

Given the agreement within the guidance, and the threat for modest
probs exceeding local FFG markers, a SLGT risk was added across the
area extending from west of Kansas City in eastern KS, down into
northeast OK and clipping the counties in AR/MO along the
neighboring state lines of KS/OK.

...Midwest into the Mid Atlantic...

20Z Update: Widespread thunderstorm development is anticipated
over the eastern half of the CONUS as we move through Saturday
afternoon and evening with pulse convection most likely for a
majority of the region with perhaps more organized cell clusters
over the Upper Midwest into the Great Lakes thanks to shortwave
progressions over the area. Vorticity maxima will slide eastward
over the top of the broad ridge drifting eastward off the Atlantic
coast leading to more return flow and lower prospects of mid-level
subsidence capping the threat of convection. HREF probs for >2"
show a "popcorn-like" output in various little maxima all over the
eastern CONUS from the Mid Atlantic into the Ohio Valley with more
maxima showing up across the Upper Midwest and northern MI. Any
thunderstorm will be capable of producing local rates of 1-2"/hr
which could result in isolated cases of flash flooding over a broad
area with the focus likely within any urban corridors or complex
terrain (Appalachia). A broad MRGL risk exists over the above
regions to account for the threat.

Kleebauer


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