From Mike Powell@618:250/1 to All on Mon Aug 11 08:34:50 2025
AWUS01 KWNH 111239
FFGMPD
SCZ000-111600-
Mesoscale Precipitation Discussion 0905
NWS Weather Prediction Center College Park MD
838 AM EDT Mon Aug 11 2025
Areas affected...Greater Charleston SC Metro
Concerning...Heavy rainfall...Flash flooding possible
Valid 111237Z - 111600Z
Summary...Heavy thunderstorms with hourly rainfall of 2 to 3
inches should continue to lift up the SC coast this morning. At
the current pace, the heavy rates would impact Charleston near
morning high tide which would enhance localized flooding.
Discussion...A band of heavy thunderstorms is currently pushing
inland and up the coast between Hilton Head Island and Charleston.
This is being fed by 25kt Sly flow with PW still around 2.25" with
a high instability gradient with 3000 J/kg just offshore per the
RAP. Max hourly rainfall is estimated from KCLX in Charleston
County south of the Charleston metro.
As onshore flow persists this activity should persist along and
just inland from the coast with a northward trend. This would
place torrential rain over the Charleston metro near the 10a high
tide which would enhanced the localized flooding risk.
Furthermore, the 1hr FFG is generally around 2.5", so localized
flash flooding is possible over the areas impacted by this heavy
band. As of now the offshore component of the activity is somewhat
disorganized and the cloud tops have recently begun a warming
trend. However, given the high instability, redevelopment is
possible which makes for a possible flash flood risk rest of the
morning around the greater Charleston metro.