AWUS01 KWNH 180630
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-181130-

Mesoscale Precipitation Discussion 1180
NWS Weather Prediction Center College Park MD
129 AM EST Wed Dec 18 2024

Areas affected...Southeast MO...Northeast AR...Southern
IL...Northwest TN...Western KY...

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

Valid 180630Z - 181130Z

SUMMARY...Warm advective showers/thunderstorms likely to expand in
coverage/intensity toward early morning.  Training/repeating
across wet/dormant grounds with low FFG suggest spots of 2-3" may
result in localized flash flooding conditions.

DISCUSSION...06z Surface analysis shows southerly return flow
across MS and W AL northward into W TN has pressed the warm front
into SW KY with lower 60s and upper 50s Temps and Tds starting to
trickle in through the MS Valley.  Aloft, CIRA LPW and VWP network
show and increasing moisture plume on 30-35kts of 850-700mb WAA
across AR into the Tri-Rivers area bringing overall deeper layer
moisture values over 1.25" with short-term totals likely to near
1.5" about 09z.  The combining streams, low level WAA profile with
modest lapse rates aloft have seen a steady increase in CAPE with
500-1000 J/kg analyzed across SE MO/NE AR at this time also to
focus into a nice SW to NE plume of 1000 J/kg by 09zZ into S IL/W
KY.  As such, regional RADAR and GOES-E SWIR show scattered
thunderstorms W KY/E TN with greater cooling towers across SE MO
into NE AR with some tops reaching -60 to -65C; under increasing
influence of right entrance ascent/evacuation aloft of 100kt 3H
jet over N MO/N IL.

Given the strength of flux and available moisture, cores can be
capable of intense short-term rates with hourly totals of
1.25-1.5" given progressive/faster cell motions.  Orientation of
cell development to the mean flow along with the scattered
downstream development (and heavier cells across NW TN/SW KY
earlier this evening) will allow for repeating over grounds that
already have 0-40cm soil moisture ratios well above normal (95+
percentile) over 60%.  Hourly FFG values only further decrease
from west to east with hourly values of 1.5"/hr and 2-2.5"/3hrs
reducing to 1" and 2-2.5", respectively across central KY/TN.=20=20

Toward 12z, overall low level profile will continue to align SW-NE
and increase LLJ strength into the 35-45kt range.  This should
allow for the scattered cells to orient into a longer linear
convective line from NE to SW though eastward propagation will
increase reducing the potential for training...all considered
scattered incidents of flash flooding are possible through the
morning toward daybreak.=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!40Ie6Zq5yf8uB3MWqhWVGlCzKo9snejZAtX0MOTAzCi4qiOLLicShXJEzclSO_LIt0TM=
IH5zPZN3bVkbZs6gL20vIaE$  for graphic product...

ATTN...WFO...LMK...LZK...MEG...OHX...PAH...

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

LAT...LON   38218612 37798561 37208571 36798642 36078824=20
            35469063 36109101 36699093 37299000 37878855=20
            38198741=20

=3D =3D =3D
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