Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Aug 27 2023 18:52:21

AWUS01 KWNH 271852
FFGMPD
VAZ000-NCZ000-SCZ000-280050-

Mesoscale Precipitation Discussion 0990
NWS Weather Prediction Center College Park MD
251 PM EDT Sun Aug 27 2023

Areas affected...eastern/central NC into northern SC

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

Valid 271850Z - 280050Z

SUMMARY...Locally heavy rainfall with rainfall rates in excess of
3 in/hr at times is expected for portions of NC into northern SC
through the early evening. This will support a localized flash
flood threat across the region with potential for storm totals in
excess of 3-5 inches.

DISCUSSION...1815Z visible satellite imagery, regional radar and
surface observations showed a small cluster of thunderstorms over
the eastern Coastal Plain of NC, between Albemarle and Pamlico
Sound. This cluster formed as the result of merging boundaries
related to early morning convection across the region and slow
cell movement has resulted in high end rainfall rates with a 1724Z
report of 1.3 inches in 15 minutes roughly 15 miles southeast of
Plymouth, NC (Wunderground.com). Visible imagery also showed
developing TCu from northern SC into south-central NC where 18Z
SPC mesoanalysis data showed 1000-2500 J/kg MLCAPE and PWATs of
2.0-2.3 inches. 850-300 mb mean layer winds averaged 10-15 kt from
the west in northern NC, weakening to less than 10 kt in northern
SC, which will support slow cell movement.

Continued heating through mostly clear skies over most of SC into
central/eastern NC will likely support some further increases in
instability over the next couple of hours. Thunderstorms are
expected to expand in coverage as surface convergence along a
synoptic scale quasi-stationary front (extending west-east through
the Carolinas) combines with sea breeze and outflow boundary
interactions. A lack of vertical shear aloft will keep storms
disorganized in nature but the efficient thermodynamic environment
should support rainfall rates of 2-3 in/hr, locally higher than 3
in/hr at times as a result of cell mergers and slow cell movement.
The region has largely been lacking rainfall over the past couple
of weeks and the typical high FFGs across most of the Carolinas
should limit the spatial scale of flash flooding. However,
localized flash flooding will still be possible through 01Z,
focused within typical flood prone locations, especially urban
areas and other locations of poor drainage, as a result of rapid
inundation of water.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_buBUPeBKjBAjOyzz0om_vVXFYzW5OLAG4yaHVVETp7JrQHU-FYISPrtvEiC0o1xGmhN=
nd0wDHfct2e_BEgBR05f0Ro$  for graphic product...

ATTN...WFO...AKQ...CAE...GSP...ILM...MHX...RAH...RNK...

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

LAT...LON   36627602 35907535 35087552 34577641 34137782=20
            34047964 34438125 35228148 36048078 36177934=20
            36347772=20

=3D =3D =3D
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