Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Dec 09 2023 19:06:47

AWUS01 KWNH 091906
FFGMPD
TNZ000-KYZ000-INZ000-100005-

Mesoscale Precipitation Discussion 1191
NWS Weather Prediction Center College Park MD
206 PM EST Sat Dec 09 2023

Areas affected...portions of Kentucky and Tennessee

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

Valid 091905Z - 100005Z

Summary....Isolated/spotty flash flood potential exists with
fast-moving convection across southern Kentucky and western/Middle
Tennessee.  This risk will exist for the next 3-5 hours -
especially where spots of 1+ inch/hr rain rates can fall on
sensitive grounds.

Discussion...Relatively fast-moving convection (generally
250/40kt) was traveling from southwest to northeast along an axis
extending from near Memphis to near Hopkinsville, KY over the past
hour.  These cells were in a seasonably moist/unstable
environment, with 500-1500 J/kg SBCAPE and 1.1 inch PW values both
contributing to occasionally heavy rainfall.  Strong shear/flow
aloft was contributing to the fast storm motions too, although the
orientation of the cells (just ahead of a slow-moving cold front)
was allowing for training and localized spots of 1+ inch/hr rain
rates to materialize.  These rates are generally less than FFG for
most of the area, suggesting that any flash flood potential should
be limited/isolated in the short term (over the next hour or so).

With time, models/observations both suggest that upscale growth of
storms (both with foci along the synoptic surface boundary and
along expanding cold pools due to increasing convective coverage)
will allow for more forward-propagating storms that should further
limit heavy rainfall potential in any one spot.  This process
should take a few hours to unfold, however, and ongoing convective
trends suggest that spots of 1.5 inch/hr rain rates should
continue to be possible especially in the 1930-2330Z timeframe.=20
The flash flood risk is expected to be highest during this
timeframe.  This risk should steadily expand east/northeastward
over time, potentially impacting the I-65 corridor in Kentucky and
areas north of I-40 in Middle/western Tennessee through 23Z.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_oNKPieg5oR31PPoX2nfNCO3z-6K6CMyKIKhuPN47xiUFhIvlo28lL4pI6n31eJDybR9=
mpGDPFK6mg9O65BWkIqWfu0$  for graphic product...

ATTN...WFO...ILN...JKL...LMK...MEG...OHX...PAH...

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

LAT...LON   38518443 37598429 36868470 36068563 35458886=20
            36068932 36848856 38088643 38468534=20

=3D =3D =3D
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