257
AWUS01 KWNH 231149
FFGMPD
NCZ000-SCZ000-GAZ000-TNZ000-ALZ000-231747-

Mesoscale Precipitation Discussion 0830
NWS Weather Prediction Center College Park MD
747 AM EDT Thu Jul 23 2026

Areas affected...Eastern TN into NC

Concerning...Heavy rainfall...Flash flooding possible

Valid 231147Z - 231747Z

Summary...A slowly southward advancing cold front will support an
isolated to scattered flash flood risk this morning across eastern
TN into NC. Rainfall rates of 1-2"/hr with localized 2-3" totals
are expected through the morning hours.

Discussion...Regional radar imagery shows showers and
thunderstorms persisting along a cold front slowly dropping
southward from eastern Tennessee into North Carolina. The
environment is characterized by deep moisture, with precipitable
water values generally hovering between 2.0 and 2.3 inches. Deep
layer flow is aligned nearly parallel to the orientation of the
boundary, creating a favorable setup for cell training and
repeating rounds of heavy rainfall.

However, convective intensity is currently being impacted by a
thermodynamic contrast across the front and modest low to mid
level moisture convergence. While robust MUCAPE around 2000 J/kg
remains in place ahead of the boundary, instability drops to
500?1000 J/kg directly along and behind the front, where the
majority of current convective activity is anchored. This reduced
instability along the boundary is generally preventing updrafts
from becoming overly deep or intense. High resolution ensemble
guidance aligns well with these observed trends; both the HREF and
REFS depict neighborhood probabilities of 1"/hr rainfall rates
over 50%, while probabilities for rates exceeding 2"/hr generally
remain under 10%.

Antecedent conditions vary across the region. The northern edge of
the rain shield is currently traversing areas with more saturated
soils; however, the rain is gradually shifting southward into
drier areas featuring higher FFG thresholds. Hourly rainfall rates
of 1 to 2" are expected in spots, leading to 6 hour localized
accumulations peaking in the 2 to 3" range. Nevertheless, a few
stronger cells could briefly train over the same area and locally
produce totals exceeding 2" in an hour. One such training axis is
currently occurring across upslope areas of far southeast TN.
Additional flash flooding through the morning hours should
generally remain isolated in nature, but will remain possible
where rain overlaps more saturated areas and where cell training
pushes hourly rainfall over 2".

By this afternoon, the cold front will continue pushing across
southern and eastern North Carolina into northern South Carolina.
As convection moves further south and taps into the diurnally
destabilizing airmass ahead of the front, storm intensity and
rainfall rates are expected to increase.

Chenard

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...CAE...FFC...GSP...HUN...ILM...MHX...MRX...
RAH...RNK...

ATTN...RFC...ALR...ORN...NWC...

LAT...LON   36457707 36287559 35267542 34757689 34727998
            35028211 34738493 34858533 34958559 35108566
            35588491 36008280 36167988