Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
451 AM EDT Sat Jul 11 2026
Day 2
Valid 12Z Sun Jul 12 2026 - 12Z Mon Jul 13 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
EASTERN KENTUCKY AND TENNESSEE INTO THE CAROLINAS..

...Southeast Quarter of the Country...
A Slight risk has been introduced stretching from KY and TN
eastward into southern VA and the Carolinas. A well defined
shortwave/low over the KY/TN vicinity will interact with a slow
moving backdoor front to focus organized convection. High res
guidance, including the RRFS, FV3 and 3km NAM, indicates a
concentrated axis of convection capable of producing localized
totals exceeding 3". While the global GFS and ECMWF are less
pronounced with their QPF swaths the GEM regional and UKMET are
more in line with the high res guidance. The AIFS and AIGFS also
depict a corridor of enhanced QPF that generally matches the Slight
risk placement. Beneath the closed low over KY and TN, convection
may be less organized, but slow moving. Given PWs near 2" and the
possibility of saturated soils from day 1 rainfall, a flash flood
risk should continue. Across the central and eastern Carolinas PWs
over 2" combined with low level southerly moisture transport and
backdoor frontal convergence should create an environment for high
rainfall rate driven flash flood potential.

Surrounding the Slight risk, a broad Marginal encompasses eastern
NM, TX and much of the Southeast. A southward advancing cold front,
the aforementioned mid level shortwave/low, and upper jet support
will provide the necessary synoptic forcing for scattered
convection. PWs over 2" and CAPE of 2000-3000 J/kg where daytime
heating is maximized, will support heavy rainfall rates. Some
mesoscale uncertainty exists with the track and strength of the
shortwave and frontal positions. An embedded Slight risk or two
may be needed on future updates as confidence increases. Increasing
low level westerly flow along the central Gulf Coast provides a
signature for backbuilding and training, but model divergence on
the exact axis remains. Given the higher regional FFG, did not
want to go with an overly large Slight risk at this time.

...Southwest...
Monsoonal moisture and instability will expand northwestward on
Sunday, necessitating a broader Marginal risk across AZ. While an
embedded Slight risk may eventually be needed, lingering questions
regarding storm coverage and organization keep the risk at
Marginal for now. Current indications suggest that while robust
convection will initiate over the terrain, it will propagate
westward quickly, potentially limiting the threat to isolate
instances of flash flooding.

Chenard


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