Mesoscale Precipitation Discussion 0776
NWS Weather Prediction Center College Park MD
134 PM EDT Tue Jul 22 2025

Areas affected...central SC/GA to coast

Concerning...Heavy rainfall...Flash flooding likely

Valid 221729Z - 222215Z

Summary...Scattered to numerous thunderstorm coverage across the
Coastal Plain of SC/GA into inland locations through the afternoon
will likely allow for at least isolated flash flooding. High
rainfall rates will support the potential for 5+ inches of rain in
one or two locations.

Discussion...17Z visible imagery from GOES East showed a small
cluster of thunderstorms located about 50 miles offshore of the
Pee Dee coast of SC, along with rapid cumulus development across
inland locations near and north of I-26. These areas of
development were located near/north of a diffuse quasi-stationary
front which draped east to west across southern SC. PW values were
anomalous across the region (12Z CHS showed 90-95th percentile)
and surface heating through mostly clear skies was contributing to
MLCAPE values of 2000-3000 J/kg along with little to no convective
inhibition per 17Z SPC mesoanalysis data.

Continued thunderstorm development is likely over the next 1-3
hours in the vicinity of weak convergence associated with the
quasi-stationary front, a developing sea breeze boundary and
resultant outflows. Steering flow is very weak at 5 kt or less
across the southern half of SC into GA, which will contribute to
very slow cell motions. Low level flow oriented roughly parallel
to the coast from the north and short term RAP development of a
surface low in eastern GA should contribute to convective clusters
evolving toward the south and west with time. While weak wind
shear aloft will prevent organized thunderstorm development, slow
movement, cell/outflow mergers and potential for at least brief
upstream cell development are expected to allow for very high
rainfall rates with 2-4 in/hr possible and perhaps sub-hourly
totals of 1 to 2 inches in 15-30 minutes. While this area of the
U.S. typically needs a lot of rain to cause flash flooding, these
high rates could overlap with urban areas and there will also be
potential for one or two areas to pick up 5+ inches of rain. These
high rainfall values are expected to lead to at least isolated
flash flood development.

Otto

ATTN...WFO...CAE...CHS...FFC...ILM...

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

LAT...LON   34157871 33747833 33157875 32237998 31838131
            32338321 33258352 33738263 34088114 34047995