Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jan 08 2023 06:31:54

AWUS01 KWNH 080631
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-081230-

Mesoscale Precipitation Discussion 0029
NWS Weather Prediction Center College Park MD
130 AM EST Sun Jan 08 2023

Areas affected...southeastern TX into central LA/MS

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

Valid 080630Z - 081230Z

Summary...A localized flash flood threat will continue across
portions of southeastern TX into central LA and central MS through
12Z. Hourly rainfall totals of 2 to 3+ inches and short term
training will support a localized threat for an additional 3-5
inches of rain through 12Z.

Discussion...06Z surface observations placed a wavy cold front
extending southwest from a low along the AR/MS border into
southeastern TX. Radar imagery showed thunderstorms primarily
along/just ahead of the cold front (and outflow boundary in
northern LA) but with some warm advection showers approaching
Galveston Bay and post-frontal showers over east-central TX.
Observed hourly rainfall rates within some of the slower moving
cells near the front, which has been aligned with the steering
flow aloft, have been in the 3-4 inch range, within an environment
characterized by MLCAPE of 500-1500 J/kg and precipitable water
values of 1.2 to 1.5 inches (via recent SPC mesoanalysis data).
The approach of shortwave troughing from the west has allowed the
cold front over TX to begin advancing more steadily toward the
southeast, which has helped to move individual cells in a more
progressive manner.

There will remain some threat for localized flash flooding over
the next few hours however, with cell mergers and brief training,
which may produce hourly rainfall totals near 3
inches...especially over southeastern TX where instability will be
maximized relative to locations farther east. However, slower
frontal/outflow progression from LA into MS may support a greater
threat for training. A limiting factor for flash flooding from LA
into MS will be reducing instability as forecast by recent runs of
the RAP through 12Z, which should cap hourly totals in the 1 to 2
inch range. Despite some lower flash flood guidance values into
central MS, the flash flood threat may remain limited to urban
locations or those with known poor drainage.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7NijYkvr7QoM0Bd8virkrqlRrakR9Hr4Nnit7Ixe6KxNyAWFh1Oc7m_WjDcQLs2vP08m=
MHplgNxOUY9zr18Q8Ugzn_s$  for graphic product...

ATTN...WFO...CRP...EWX...HGX...JAN...LCH...LIX...SHV...

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

LAT...LON   33508928 33258893 32648935 32019032 31309144=20
            30219276 29169420 28329593 28239733 28999749=20
            29749593 30499491 31259445 32519224 33249070=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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