Mesoscale Precipitation Discussion 1035
NWS Weather Prediction Center College Park MD
743 AM EST Sun Dec 02 2018

Areas affected...Florida Panhandle, southern Georgia, southern
South Carolina

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

Valid 021242Z - 021802Z

Summary...Flash flooding will remain possible through the morning
hours as an axis of convection persists.

Discussion...A persistent corridor of convection continues to
stream northeastward from the northern Gulf into the FL Panhandle,
far southeast AL and southern GA. This activity is focusing along
an axis of strong low level convergence ahead of the cold front.
This convergence axis has been nearly stationary over the last 12
to 24 hours, which has resulted in widespread 2-4" rains, with
more scattered 4-6"+ totals. This rainfall has likely resulted in
saturating soil conditions and a lowering of the flash flood
guidance...making additional flash flooding easier to come by.

A slow eastward progression of the convergence axis has been
noted, which should begin to push the convective axis a bit east
of where the heaviest antecedent rainfall has been. The approach
of the cold front from the west should help continue this slow
eastward progression of the training convection corridor. Although
this eastward progression will be slow, and thus at least some
training will remain likely over the MPD area.

High resolution models have been struggling with the evolution of
this convection. The tendency in the models has been to weaken the
activity and push it north and east too quickly. In reality, the
convection has persisted and remained more organized than modeled
across the Gulf Coast.  There are signs that a shortwave may be
moving northeast across GA, eventually moving into the Carolinas.
This is probably responsible for the increasing cluster of storms
and flash flood threat over southeast GA, and may result in some
decreased organization in its wake across the FL panhandle into
southwest GA.

However, recent satellite trends continue to show convective
development over the northern Gulf. MLCAPE and 850 mb moisture
transport and low level convergence are all forecast to be
maintained through the morning as well. Thus the observational and
environmental parameters suggest that training convection will
continue. So even though convective elements may be a bit more
separated and more loosely organized than before, still anticipate
training will continue through 18z, likely resulting in heaver QPF
than what is depicted by most of the CAMs.

The 10z HRRR appears to have finally caught on...and would say it
is probably the most reasonable solution going forward (although
not perfect). It depicts scattered 3-4" additional totals through
18z, which may cause additional flash flood concerns over the MPD
area.

Chenard

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

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

LAT...LON   32758118 32728071 32578044 32248054 31838105
            31768115 30988213 30388325 30188405 30178494
            30128574 30078758 30508670 30778600 31178518
            31598457 32108377 32318318 32528237 32678181