Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed May 10 2023 19:40:47

AWUS01 KWNH 101940
FFGMPD
TNZ000-KYZ000-ALZ000-MSZ000-MOZ000-ARZ000-110030-

Mesoscale Precipitation Discussion 0250
NWS Weather Prediction Center College Park MD
340 PM EDT Wed May 10 2023

Areas affected...Northern/Northeast AR...Southern MO...Western
TN...Northwest AL...Ext Northern MS...

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

Valid 101940Z - 110030Z

SUMMARY...Initially slow moving heavy rainfall producing clusters
may pose scattered incidents of highly localized flash flooding.

DISCUSSION...Full solar insolation along/just north of stationary
front across the region was further enhanced by increased cloud
coverage across central and northern MS strengthening the
differential heating boundary.  Weak confluent flow about the
boundary allowed for pooled moisture and maximized instability
with 2000-2500 J/kg of MLCAPE centered in the Delta Region of
northeast AR/western TN.   The heating difference also contributed
to weak but sufficient convergent flow across the boundary
allowing for convective initiation across the length of this area
of enhanced instability.  Strong updrafts (cooling below -60C)
with weak steering flow at the periphery of the approaching
shortwave crossing central AR yet still at the ridge in synoptic
flow regime will allow for near stationary movement initially
allowing for efficient rainfall production.  Hourly rates of
1.5-2" are expected directly under these cores, and while most are
likely to be an hour or less at a given location, some may linger
up to 2 hours particularly with the initial cores.  However, some
cells are already starting to show signs of cold pool generation
allowing for propagation or new redevelopment along the convergent
flanks (preferably toward the north).  As such, localized spotty
totals of 2-3" are possible resulting in scatter shot pattern of
highly localized, low end incidents of possible flash flooding
mainly for urban locations caught under those cores.=20

As the clusters mature, outflow boundary collisions may allow for
broader up/downdrafts while seeking out remaining pockets of
enhanced instability, potentially over-lapping adjacent
watersheds, increasing the localized flooding risk.  This scenario
 more like traditional summer time convection and, in general, is
not very confident; however, the broader areal coverage along a
more concentrated axis of enhanced moisture/instability across
northern AR/southern MO into northern AL warranted this
discussion.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!57CVeOAAclcx8zizOdEZvKGbGxLeDEoN6abNfa08L0p5D5lFdK76ITYaqlt7zPYHrejd=
SvHnkUstccbEJzkxzK0Y9lA$  for graphic product...

ATTN...WFO...BMX...HUN...LZK...MEG...OHX...PAH...SGF...TSA...

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

LAT...LON   36989213 36929100 36278867 35408734 34338646=20
            33738680 33998750 34338809 34958950 35379088=20
            35529281 36039351 36749318=20

=3D =3D =3D
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