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000
AWUS01 KWNH 182122
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-190100-

Mesoscale Precipitation Discussion 0163
NWS Weather Prediction Center College Park MD
521 PM EDT Thu Apr 18 2024

Areas affected...Arklamiss into north-central MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 182119Z - 190100Z

Summary...Localized but likely flash flooding to persist while
translating east for another few hours into central MS through
00Z. Rainfall rates over 2 in/hr can be expected.

Discussion...21Z radar imagery continued to show a west-east axis
of thunderstorms extending from the eastern AR/LA border into
central MS, with MRMS hourly rainfall totals over 2 inches at
times. MRMS-derived rainfall over the past 6 hours (ending 21Z) is
near 10 inches along the southern Ashley/Chicot County border, and
while MRMS rainfall matches a Wunderground.com station just west
of Eudora, AR with 5.74", this region resides within the melting
layer of the 3-nearest WSR-88Ds, and uncertainty exists with the
actual highest rainfall totals given a lack of ground truth.
Regardless, significant rainfall has fallen within a relatively
short period of time near the AR/LA/MS border with ongoing flash
flooding.

A mid to upper level shortwave was observed to be moving east
along the central AR/LA border with diffluent flow downstream.
Radar/infrared imagery downstream of the shortwave into central MS
has shown some signs of losing organization over the past hour.
Despite that fact, the environment will continue to favor training
heavy rain for the next 1-3 hours to the north of an outflow
boundary analyzed from northern LA into central MS with 20-35 kt
of SSW 925-850 mb flow in northern LA overrunning the rain-cooled
airmass. While some near term weakening of the low level flow will
be possible, MLCAPE estimates just south of the outflow boundary
were 1000 to 2000+ j/kg via the 21Z SPC mesoanalysis and as the
shortwave aloft continues to advance toward the east, areas of
heavy rain with training will shift downstream into portions of
central MS through 00Z. Peak rainfall rates over 2 in/hr will
remain possible at times and and an additional 2-5 inches is
expected for localized areas through 00Z or 01Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...

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

LAT...LON   33628913 33538823 33068814 32418824 32268905
            32339032 32579130 33049166 33379130 33529039