Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Sep 05 2023 17:54:59

AWUS01 KWNH 051754
FFGMPD
TNZ000-KYZ000-ALZ000-052130-

Mesoscale Precipitation Discussion 1037
NWS Weather Prediction Center College Park MD
154 PM EDT Tue Sep 05 2023

Areas affected...Central TN...Southern KY...Northern AL

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

Valid 051750Z - 052130Z

SUMMARY...Training thunderstorms containing rainfall rates >2"/hr
may result in flash flooding across portions of the Tennessee
Valley this afternoon.

DISCUSSION...Doppler radar was depicting a blossoming area of
thunderstorms southwest of Nashville. Temperatures throughout the
region have surpassed convective temperature and low 70s dew
points have supported enough buoyancy aloft to generate
thunderstorms. The 12Z BNA sounding shows PWs of 1.91" and low-mid
level winds uniform out of the SW. Upshear Corfidi vectors were
also 9 kts, suggesting the potential for backbuilding storms
training over parts of the region. RAP mesoanalysis shows MLCAPE
is now topping 1,500 J/kg and RAP forecast soundings show not only
mid level RH values >80%, but warm cloud layers were topping out
as deep as 11,000-12,000 ft.

The uniform winds at low-mid levels and both the abundance of
instability and moisture will support training storms across parts
of central Tennessee early this afternoon. Visible satellite
showed a growing field of congested cumulus over northern Alabama
as well. There is not much in the way of vertical wind shear, so
storms may not persist much longer than a couple hours. However,
MRMS 15-minute rainfall estimates show rainfall totals are topping
0.4". Given the instability and moisture these storms can tap
into, storms will have the potential to generate >2"/hr rates at
their peak. Note that 1-hr FFGs are higher, bottoming out around
2". The threat area should be rather small in coverage, but poor
drainage areas and more urbanized locations are most at-risk to
flash flooding. The SW-NE orientation of the band of storms looks
to place the immediate Nashville area in its path.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-9WKKPlhQDzSb7eIo7vVZQA6KB0CmTz3-usUKux_e5mokGfbd8TE_AUqR12Jr9JvNuEa=
8tZzaHDzbBGxtm84wyq1RKk$  for graphic product...

ATTN...WFO...HUN...LMK...OHX...

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

LAT...LON   36798626 36498601 35688626 35158665 34798726=20
            34788765 34978787 35388786 36068754 36698688=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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