713
AWUS01 KWNH 121725
FFGMPD
NCZ000-SCZ000-GAZ000-122330-

Mesoscale Precipitation Discussion 0870
NWS Weather Prediction Center College Park MD
124 PM EDT Mon Aug 12 2024

Areas affected...Carolina Coastal Plains & Extreme E GA Coast.

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

Valid 121730Z - 122330Z

SUMMARY...Lingering frontal zone and Sea Breeze convection over
saturated ground conditions continue to pose scattered but likely
flash flooding conditions in cells capable of 2-2.5"/hr and spots
of 4"+ possible.

DISCUSSION...17z surface analysis denotes pesky stationary front
from Cape Hatteras along the SE NC coast toward a surface wave
along the SC/NC state line just ashore; the front continues west
along I20 before becoming less discernible west of Athens, GA.
Enhanced moisture still over mid-70s Tds exist along both sides of
the boundary which using CIRA LPW extends through 700mb, before a
dry slot can be analyzed across south-central GA bleeding into S
Low Country of SC...however, pooling of moisture through 500mb
near the front brings total PWat Values over 2-2.25".  Of note,
early cu along the GA/SC note, that the surface moisture into the
low 80s and confluent flow will likely sharpen the sea breeze as
it develops in the next few hours.  Unsurprisingly, CAPE over 2500
J/kg exists in proximity of the front through central SC before
increasing to over 3500 J/kg along the SC/NC coast.

GOES-E WV shows polar closed low is dipping southward into the
Mid-Atlantic, and the polar jet is splitting a bit under this
influence.  So oblique right entrance ascent is going to a
favorable factor for some cell organization nearer the front but
further east.  Currently RADAR and GOES-E Visible note the initial
developing cells in E NC, which are likely to continue to deepen
and expand in coverage.  Cells very near the coast may become a
bit more locked to the coast given strengthening sea-breeze which
seems to be a solid consensus within the Hi-Res CAMs providing
increased confidence in activity.   HREF probabilities of 2"/hr
are fairly high with some isolated 10-15% values for 3"/hr across
much of E NC decreasing in coverage along the front and down the
SC coast.  High 60-70% probability in neighborhood 3"/6hr and even
a 30% of 5" is enough for probable flash flooding potential.
However, given the grounds still remain well above average in
saturation from the prolonged rainfall over the last week,
incidents of flash flooding are considered likely, especially in E
NC; with decreasing coverage potential into central SC and even
further across central and southern coastal SC where cells are
likely to be more pulse in nature given mixing of mid-level dry
air (though will have intense rainfall production in that short
duration).

Gallina

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

ATTN...WFO...CAE...CHS...ILM...MHX...RAH...

ATTN...RFC...SERFC...NWC...

LAT...LON   35817753 35737659 35727588 35227560 34897602
            34577636 34567697 34247757 33707804 33617881
            32937930 32508002 32138049 31748109 32178140
            32868113 33228167 33548197 34018173 34568060
            34967971 35617818