Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
430 AM EDT Thu Jul 9 2026
Day 2
Valid 12Z Fri Jul 10 2026 - 12Z Sat Jul 11 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE MID MISSISSIPPI VALLEY INTO THE CENTRAL APPALACHIANS...

...Mid MS Valley to the Central Appalachians...
A favorable environment for convective training and backbuilding
should take shape across portions of the OH and TN valley on
Friday. Multiple shortwaves embedded within the west to northwest
flow aloft will interact with a persistent westerly low level
moisture transport vector. This wind profile will result in very
weak Corfidi vectors, and thus upwind propagation and backbuilding
into the low level flow is probable. This setup will overlap an
unstable and moist airmass, with PWs forecast around or over 2".

Some uncertainty remains regarding convective evolution,
especially how morning convection affects afternoon
destabilization and exactly where the instability axis recovers
and sets up. There are also some differences in the
strength/timing of the convectively enhanced shortwave that will
be tracking into the area from the west. The current model
consensus consisting of the ECENS/GEFS/AIFS/AIGFS favors much of KY
into northern TN for the axis of heaviest rain. A higher end
SLight risk will cover these areas, with the caveat that the exact
axis will likely require some spatial adjustments in future
updates. Will need to continue to closely monitor the evolution of
this threat, as a setup such as this could result in an eventual
MDT risk pending model trends.

...High Plains...
Additional shortwave energy ejecting out of the Rockies will
trigger another round of convection from the TX Panhandle into CO
and KS. The low level jet and overall forcing may be a bit weaker
than Thursday, which may limit the degree of organization and
upscale growth. Nonetheless, some slow cell motions and high
rainfall rates will maintain a threat for localized flash flood
impacts.

...Arizona...
The synoptic and mesoscale setup on Friday will be very similar to
day 1, although instability maybe slightly higher. Both the RRFS
and REFS depict more robust convective development capable of
producing localized rainfall totals over 2 inches. While this risk
should remain isolated, the flash flood threat appears slightly
higher than on Thursday.

Chenard


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