Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Dec 14 2022 02:44:45

AWUS01 KWNH 140244
FFGMPD
MSZ000-LAZ000-ARZ000-140800-

Mesoscale Precipitation Discussion 1159
NWS Weather Prediction Center College Park MD
944 PM EST Tue Dec 13 2022

Areas affected...Northern LA...Southeast AR...Northern to
Southwest MS...

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

Valid 140245Z - 140800Z

SUMMARY...Progressive line with embedded rotating cells capable of
intense short-term 2-2.5" totals & possibility of merging
pre-cursory supercells may allow for spotty scattered 2-4" totals
and few possible flash flooding incidents.

DISCUSSION...GOES-E WV suite depcits an impressive deep closed
cyclone over the Central Plains with well defined warm conveyor
belt across the Lower Mississippi Valley with classic wedge of
convective overshooting tops progressing east. Stronger cells are
blossoming along and north of the anticyclonically curved
subtropical jet cirrus streaking out of southeast TX across LA.=20
RADAR mosaic shows the line is a bit more broken extending
southwest into southeast TX, with a few pre-cursory supercells
ahead of the line across NE LA into W MS.=20

Strongest confluence/convergence resides along and southeast of a
subtle shortwave/MCV lifting north along the conveyor belt east of
Little Rock moving quickly northeast.  Over 20kts of Sfc SEly flow
with mid to upper 60s Tds is fairly orthogonal to the line, and
with deepening moisture plume reaching a total of 1.75" across W
MS.  Stream of 50-60kt 850mb flow is adding to the flux, but is
starting to be less orthognal to the line.  Still, the strength of
the moisture convergence, particularly with embedded rotating
updrafts...support very high rainfall efficiency and rain rates of
2.0-2.5"/hr.  Cell propagation is fairly quick, particularly
further north nearer best diffluence in the polar jet, limiting
duration, but potential for mutliple rounds and broader
updrafts/downdrafts near the apex across SE AR/N LA into W MS will
support some stripes of 2-4" potential through to 09z.

While the area has been recently dry per AHPS 7 to 14 day
anomalies, NASA SPoRT LIS 0-40cm relative soil moisture is about
50%, so given how quick the rain will fall, it should saturate
fairly quickly and support increased run-off and result in a few
incidents of possible flash flooding.=20=20

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7DoVFGo42ZgrPNi07mKUJPzLPXkeTFuwkhYvz54m7FCD6pM7UiRir6Sb_gmfkisC4WUk=
bioQjlvRFKeWBtu__MRUQA0$  for graphic product...

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

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

LAT...LON   34949025 34828867 34188850 33638874 32598961=20
            31719061 31549263 31579345 31989347 32789271=20
            33609199 34789135=20

=3D =3D =3D
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