958
AWUS01 KWNH 071008
FFGMPD
SCZ000-GAZ000-071530-

Mesoscale Precipitation Discussion 1135
NWS Weather Prediction Center College Park MD
508 AM EST Thu Nov 07 2024

Areas affected...Southeast GA...Southern SC...

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

Valid 071010Z - 071530Z

SUMMARY...Flooding likely to continue though potential for intense
rain-rates capable of inducing flash flooding reducing with time
and overall coverage.

DISCUSSION...A large area of 4-10" rainfall extends across eastern
GA into southwest to south-central SC with slow expansion toward
the coastal Plain over the past few hours.   Large scale ascent
pattern remains fairly strong with upper-level divergence pattern
along right entrance of broad polar jet across the Carolinas.
However, the area is shifting east-northeast and reducing
slightly.  Still, this is maintaining a solid dual fetch of
low-level flow from the northeast Gulf as well as off the Gulf
stream parallel to the NE FL/GA coast.  Cold pool from the heavy
rainfall continues to allow for a moderately steep isentropic
boundary across the area from SE GA into the Low Country, with a
very slow east-southeast drift due to the responding low level
inflow from the south-southeast.  VWP denotes continued 20-25kts
of SE flow nearly orthogonally intersecting the boundary and
northeasterly flow across central SC.  CIRA LPW and RAP analysis
denote deep profile of highly anomalous moisture with values of
2.25" through depth with sfc-850mb over from .9" to 1.15" across
the area of concern; so dynamics and moisture continue to be in
place to maintain rainfall efficiency.

However, unstable air mass continues to diminish in areal coverage
and intensity as the profile becomes more staturated and warms
aloft; restricting itself to the Gulf Stream and coastal GA where
low level flow has been generally divergent before starting to
accelerate into SE SC where convergence is maximized.  Values of
500-1000 J/kg remain but only along the upstream edge of the
complex along the Savannah River Valley.   As such, limited
overall convection capable of rates over 1.5-2"/hr are expected
over the diurnal minimum in activity of early morning/daybreak,
mainly near/southeast of mid-level exiting shortwave seen near
Wilkenson county, GA or at the 700-850mb low feature seen in RADAR
in Montgomery county.  Smaller localized spots of 2-4" totals
remain possible to induce new incidents of flash flooding though
the 15z period.

Moderate downstream blow-off shield precipitation within the more
gentle isentropic ascent pattern will maintain moderate rainfall
rates across the flooded areas from Emanuel to Orangeburg with
counties with occasional hourly rates exceeding .5".  This will
likely help to maintain the expanding riverine flooding as pluvial
flooding continues to channel into localized creeks/streams.  An
additional 2-3" remains possible through the morning hours given
favorable upstream redevelopment and training as the upper-level
forcing moves northeast.

As such, flooding will remain likely across the area of concern,
though incidents of flash flooding are considered possible given
reducing coverage/intensity required to exceed FFG where heavier
rain did not fall last evening/overnight across coastal E GA/S Low
Country of SC.

Gallina

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

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

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

LAT...LON   34118019 33907956 33397924 32977945 32757980
            32578007 32208058 31698098 31418123 31528156
            31888193 32048228 31938282 32008307 32298309
            32688271 33158214 33478172 33678137 34038071