Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jan 18 2023 17:03:01

AWUS01 KWNH 181702
FFGMPD
TNZ000-KYZ000-ILZ000-MSZ000-LAZ000-MOZ000-ARZ000-TXZ000-182300-

Mesoscale Precipitation Discussion 0046
NWS Weather Prediction Center College Park MD
1202 PM EST Wed Jan 18 2023

Areas affected...western LA/AR border into MO Bootheel/MS Valley

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

Valid 181701Z - 182300Z

SUMMARY...From northwestern LA into the lower/middle MS Valley,
periods of southwest to northeast training will have the potential
to support rainfall rates of 1-2 in/hr and localized totals of 2
to 3+ inches through 23Z. Localized flash flooding may result
where these higher rates develop.

DISCUSSION...16Z surface observations showed an occluded cyclone
across the Southern Plains with a cold front extending
southwestward from western AR into northeastern TX and a warm
front extending eastward across northern AR into TN. Regional
radar imagery showed prefrontal convection stretching along a
broken axis from northeastern TX into northwestern LA and central
AR, with a few isolated cells to the east over eastern AR.
Transient areas of low level, prefrontal convergence were helping
to support the ongoing thunderstorms with a more contiguous axis
of lift located along the cold front.

Low level moisture return was evident in layered precipitable
water imagery from the Gulf Coast, northward ahead of the cold
front. Sufficient instability (500 to 1000 J/kg MLCAPE south of
the warm front per SPC mesoanalysis at 16Z) and shear were in
place, supporting a few organized cells and supercell structures,
containing higher rainfall rates of 0.5 to 1 inch in 15 minutes
per MRMS data.

Thunderstorms are likely to expand northeastward through AR over
the next 1-2 hours as lift ahead of the cold front translates
eastward. Areas of training will be most likely with any cells
that form out ahead of the main line, followed by convection with
the cold front itself or where northern portions of linearly
oriented convection races out ahead, setting up an orientation
that matches the deeper-layer steering flow from the southwest.
Training will support the potential for 1 to 2+ inches per hour
and localized totals of 2 to 3+ inches through 23Z. Flash flood
guidance varies across the region but is lowest across northern
sections of the discussion area and highest from southern AR into
LA. Any areas of flash flooding that develop are expected to be
isolated in nature.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_wQDSiibxzxIjcYC7_XsV5333xv3MMYr-PbXkaS98YWA5YMEwuXiedDgktVEmZruLbMA=
8WDT8XjzxtFPKMn4wjxHeqA$  for graphic product...

ATTN...WFO...JAN...LSX...LZK...MEG...PAH...SGF...SHV...

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

LAT...LON   37618872 36398887 34559052 33349185 32669321=20
            33129406 35409249 37529006=20

=3D =3D =3D
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