Subj : MESO: SE Heavy Rain/Flood
To   : All
From : Mike Powell
Date : Tue Aug 29 2023 20:07:00

AWUS01 KWNH 300041
FFGMPD
NCZ000-SCZ000-GAZ000-TNZ000-ALZ000-300500-

Mesoscale Precipitation Discussion 1006
NWS Weather Prediction Center College Park MD
840 PM EDT Tue Aug 29 2023

Areas affected...northern GA...northeast AL...adjacent portions of
East TN and far western NC

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

Valid 300035Z - 300500Z

Summary...Isolated instances of flash flooding possible with
1-2"/hr rainfall rates, localized totals of 2-4".

Discussion...Slow moving showers and thunderstorms have developed
in and around the Atlanta metro area, as well as farther north
along portions of the southern Appalachians. The mesoscale
environment is characterized by SB CAPE of 1000-2000 J/kg, PWATs
of 1.7-2.1" (between the 90th percentile and max moving average,
per FFC sounding climatology), and less than 20 kts of effective
bulk shear (with 850-300 mb mean layer flow of 10-15 kts). While
thunderstorm longevity is not expected to last long due to lack of
deep layer wind shear, an outflow boundary that have moved in from
the southeast has been the focus for development through portions
of the north Atlanta metro. The deep layer mean flow is oriented
parallel to this outflow boundary (towards the northeast), which
may allow for some limited training of 1-2"/hr rainfall rates.
Some of this activity may also extend west and north into portions
of northeast AL and adjacent portions of East TN and far western
NC. Isolated instances of flash flooding are possible over the
next several hours, with expected localized totals of 2-4".

Churchill

ATTN...WFO...BMX...FFC...GSP...HUN...MRX...

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

LAT...LON   35938368 35598315 34798315 33818386 33218548 
            33648689 34218639 35038521 35488443 

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