819
AWUS01 KWNH 112010
FFGMPD
FLZ000-GAZ000-120209-

Mesoscale Precipitation Discussion 0647
NWS Weather Prediction Center College Park MD
410 PM EDT Fri Jul 11 2025

Areas affected...portions southern GA

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

Valid 112009Z - 120209Z

Summary...Backbuilding thunderstorms with possible mergers with
activity approaching from the south are expected to continue to
lead to hourly amounts to 2.5" and local totals to 4".

Discussion...Showers and thunderstorms have formed within a moist
and unstable air mass with precipitable water values of 2"+ and ML
CAPE of 2500-3000 J/kg.  Effective bulk shear is roughly 20 kts
per the Peachtree City GA and Jacksonville FL soundings, which
appears to have been sufficient for some level of convective
organization, as there have been backbuilding signatures as of
late.

Both the 12z HREF and 06z RRFS probabilities are stuggling in this
area, with the HREF indicating western areas fairly well and the
RRFS having some concept of issues in more eastern areas within
the MPD area.  Because of this, am having to rely upon conceptual
models more than usual, which leads to confidence being no better
than average.  The existing thunderstorm activity should build a
little further before ending from west to east as thunderstorm
outflow from activity to the south tries to exhaust the available
instability.  As outflow from the two convective areas intersect,
there could be a tendency for thunderstorms with heavy rain to
"zipper" along the outflow boundary intersection from west to
east.  Hourly rain amounts to 2.5" and local totals to 4" could
lead to isolated to widely scattered flash flood concerns into
this evening due to backbuilding, cell mergers, or new convective
development along the upcoming outflow boundary intersection.

Roth

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

ATTN...WFO...CHS...FFC...JAX...TAE...

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

LAT...LON   32908297 31548125 31028130 30558139 30718222
            31668346 31858410 32278424