AWUS01 KWNH 231117
FFGMPD
SCZ000-231616-

Mesoscale Precipitation Discussion 0980
NWS Weather Prediction Center College Park MD
716 AM EDT Sat Aug 23 2025

Areas affected...coastal areas of South Carolina

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

Valid 231116Z - 231616Z

Summary...Localized areas of flooding are expected over the next
4-6 hours (through 16Z/noon EDT) as convection over the Gulf
Stream slowly migrates inland toward coastal areas of South
Carolina.

Discussion...Recent radar/satellite imagery indicates a fetch of
deep convection along an axis from near Charleston to about 80-100
miles east-southeast of Charleston. The convection was likely
being maintained by several synoptic features, including 1) a
mid-level vorticity maximum over Georgia that was providing ascent
aloft over the region and 2) low-level easterly flow just north of
a weak low near Savannah that was helping to maintain moderate
instability (1000+ J/kg SBCAPE) right along coastal areas. An
abundantly moist airmass (2.3 inch PW) remains in place,
supporting efficient rainfall processes with stronger cells that
develop. Additionally, parts of the region experienced 3-8 inches
of rainfall over the past 24 hours, and onshore flow was
persisting during this morning's high tide, which was likely
resulting in inundation of low-lying coastal areas along with
hindered runoff/drainage.

The ongoing convective trends should continue for the next 4-6
hours. Areas of 1 inch/hr rain rates have began near Charleston
over the past 30 minutes, and these rates should continue
periodically while the convective axis in maintained in the
region. Areas of 2-3 inch rainfall totals are expected. Over
time, the convective axis should drift northward and/or weaken (as
depicted by CAMs), although this process should take several hours
to unfold.

Flooding is possible along coastal areas this morning and could be
enhanced by the locally heavy rainfall that periodially moves
onshore.

Cook

ATTN...WFO...CHS...ILM...

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

LAT...LON 33677915 33507868 32378027 32728065 33387996


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