Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Sep 17 2023 16:02:37

AWUS01 KWNH 171602
FFGMPD
NCZ000-SCZ000-GAZ000-172200-

Mesoscale Precipitation Discussion 1081
NWS Weather Prediction Center College Park MD
1201 PM EDT Sun Sep 17 2023

Areas affected...South Carolina

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

Valid 171600Z - 172200Z

SUMMARY...Heavy showers and thunderstorms will tend to be
expanding in coverage heading through the afternoon hours across
much of central and eastern SC. A localized threat of flash
flooding will exist, and especially for the more urbanized
locations.

DISCUSSION...A return of deeper moisture and instability out ahead
of an upper-level trough moving into the eastern U.S. will yield
an expanding axis of heavy shower and thunderstorm activity going
through the afternoon hours across much of central and eastern
S.C. Facilitating this convective threat will be the northeast
advance of a warm front and a weak area of low pressure up across
the Piedmont of the Southeast.

Stronger low-level convergence/forcing along with moisture
transport into this boundary will tend to result in pockets of
locally focused/organized convection capable of producing very
heavy rainfall rates. The PWs are already locally exceeding 1.75
inches, and with MLCAPE values of 1000 to 1500 J/kg across the SC
Lowcountry. The combination of this along with a belt of 30+ kt
effective bulk shear values will tend to favor convection with
enhanced rainfall rates capable of producing rainfall rates up to
2.5 inches/hour.

The 12Z HREF guidance suggests some localized potential for 3 to 5
inch totals heading through the afternoon hours as the convection
tends to grow upscale a bit more and advances off to the east.

These rains may result in at least some localized flash flooding
concerns despite high FFG values. The bigger concerns will tend to
be the more sensitive urban areas where these high short-term
rainfall rates may result in enhanced runoff potential.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5Iy2ZYHQ1E6MF0Hcp3pLnFf9Zwml6G4FQ9-M5ves449Kik-W1qWjT0lUwm9yqEZjvcC8=
rkkAtUTFsIuYuIGwWzXuXZ0$  for graphic product...

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

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

LAT...LON   34727995 34537928 34077886 33597891 33117928=20
            32577988 32018062 32008112 32438136 33108144=20
            33818132 34448079=20

=3D =3D =3D
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