Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jun 20 2023 23:24:57

AWUS01 KWNH 202324
FFGMPD
NCZ000-SCZ000-GAZ000-TNZ000-210500-

Mesoscale Precipitation Discussion 0543
NWS Weather Prediction Center College Park MD
723 PM EDT Tue Jun 20 2023

Areas affected...Western Carolinas...Northern GA...Eastern TN

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

Valid 202320Z - 210500Z

SUMMARY...Rounds of heavy storms to persist into the evening hours
will contain downpours and may lead to additional flash flooding,
especially in areas with highly sensitive soils.

DISCUSSION...Strong high pressure over New England and low
pressure in the Mid-South continues to keep the Carolinas and
southern Appalachians in the cross-hairs of a seemingly endless
conveyor belt of Atlantic and Gulf of Mexico moisture. The
easterlies at 850mb continue to act as an excellent moisture
transport for thunderstorms to use and produce excessive rainfall
rates. RAP mesoanalysis shows much of the region has at least 1.5"
of PWATs present with values close to 2" east of Charlotte. 21Z
HRRR area averaged soundings continue to show a highly saturated
atmosphere with >90% RH values at low-mid levels from eastern TN
to west-central NC. Warm cloud layers are also averaging
11,000-12,000' in these areas. Even after the sun sets, expect
500-1,000 J/kg of MLCAPE to be available and weak (but still
beneficial) vertical wind shear to stick around this evening.

The region has continued to watch its soils become increasingly
saturated with each passing hour, it seems. The latest 18Z HREF
favors northwest SC with the highest percent probabilities
(30-40%) for 3-hr QPF > 3-hr FFGs. Meanwhile, west-central NC and
surrounding the Knoxville area have also seen 300-400% of normal
rainfall over the past 7-days. Thunderstorm coverage and intensity
should wain deeper into the overnight hours as instability
diminishes, but the steady onslaught of rich moisture and
sufficient lift aloft keeps heavy thunderstorms in the forecast
through the first half of the night. Additional flash flooding is
possible, especially in urbanized settings and areas with
sensitive soils. There is also the potential for landslides in
parts of western SC and western NC where some areas in complex
terrain have picked up 5"+ over the last 24-36 hours.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5hrBP8K6FZA21shb3N3JXxb19eyYCu89se4ppGuGoFDVEZOmLhLYj7tS9qNiSSFA6Qpl=
CeZq6WTNgv08f4WlW-UshF4$  for graphic product...

ATTN...WFO...CAE...FFC...GSP...MRX...RAH...RNK...

ATTN...RFC...LMRFC...OHRFC...SERFC...NWC...

LAT...LON   36548110 36277979 34977994 34388084 34508185=20
            34138273 34078367 34448400 35498456 36258401=20
            36218272=20

=3D =3D =3D
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