Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Dec 18 2024 09:16:23

AWUS01 KWNH 180916
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-181400-

Mesoscale Precipitation Discussion 1181
NWS Weather Prediction Center College Park MD
415 AM EST Wed Dec 18 2024

Areas affected...Southern Arkansas...Adj SE OK/NE TX/N LA...

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

Valid 180915Z - 181400Z

SUMMARY...Flattening convective line shows potential for training
over the next few hours while crossing saturated soils from recent
heavy rainfall across southern AR.

DISCUSSION...Recent GOES-E 10.3um and regional RADAR trends
suggest upwind edge of best isentropic convergence across SE OK
has seen a recent uptick in convective development.  WV suite
depicts the right entrance of a speed max in the cirrus across
central OK at this time.  This is resulting a downstream shortwave
ridging and flattening of the 500-1000mb thickness ridge allowing
for a more eastward propagation of the convective line likely over
the next few hours.  CAPE analysis fields suggest highest theta-E
axis is ideally oriented for the isentropic ascent along the Red
River Valley.  Cooling tops below -65C suggests stronger updrafts
and deeper moisture flux/rainfall production.  CIRA LPW places .6
to .75" sfc-850mb moisture with additional 850-700mb layer over
..3-.5" allowing for totals of 1.25" to 1.4"; given 30-35kts of
flow; flux convergence will support rates of 1.5-1.75" and given
the orientation may allow for 1-2 hours of training before the
core of height-falls across W OK/NW TX dig more and start to
accelerate the cold front south and eastward and reduce the best
ascent angle to the front from the LLJ.  As such a streak or two
of 1.5-2.5" totals remain probable across Texarkana and southern
Arkansas.

Unfortunately, heavy rainfall last evening has reduced upper level
soil capacity across this area with NASA SPoRT 0-40cm saturation
ratios well above normal in the 65-75% range.  So believe FFG
values may have likely recovered too fast and grounds may be more
susceptible to increased run-off and potential for localized flash
flooding.  By no means will the rainfall totals be great enough
for sizable areal coverage and/or magnitude of flash flooding, but
the potential remains sufficient for an incident or two to occur
through mid-morning across S Arkansas.=20

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8ImBU7gdw3rEfK9MDyfI6Z8EhZJG1sGH7v7E9YKCKFHrFJ-g4cmmyOqL0Ji0NIw6JTO0=
tOWh3VyxLlWscqrydoWoCH8$  for graphic product...

ATTN...WFO...JAN...LZK...SHV...

ATTN...RFC...ABRFC...LMRFC...NWC...

LAT...LON   34969203 34799153 34209115 33829110 33209133=20
            32859199 32859382 33179485 33789516 34319482=20
            34629404 34939286=20

=3D =3D =3D
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