AWUS01 KWNH 151130
FFGMPD
TNZ000-MSZ000-LAZ000-ARZ000-151700-

Mesoscale Precipitation Discussion 0061
NWS Weather Prediction Center College Park MD
730 AM EDT Sat Mar 15 2025

Areas affected...Northern Louisiana, Northwestern Mississippi, &
Western Tennessee

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

Valid 151129Z - 151700Z

SUMMARY...Training cells along a stationary upper level boundary
will likely pose a flash flooding threat through the morning with
rates locally exceeding 2 inches per hour. Flash flooding is likely.

DISCUSSION...A very dynamic scenario is unfolding across
northwestern Mississippi this morning as a stationary upper level
boundary acts as a forcing mechanism for storms that are already
forming. Low level SSE flow is advecting plentiful Gulf moisture
characterized by dew points near 70 degrees and SBCAPE values over
2,000 J/kg into the region. At 850mb, a south-southwesterly LLJ
has strengthened to near 50 kts, which will keep a steady supply
of moisture advecting into the front. Meanwhile a potent shortwave
across northeast Texas is approaching the region, which will add
even more forcing. This will both strengthen the storms training
along the front and broaden the precipitation shield over the
area, meaning many areas will not see a break in the rainfall.

1-hr FFGs in this region are generally between 1.5 and 2.5 inches,
which will both come down with the early morning convection
already breaking out, and with the later additional forcing will
support even stronger convection capable of rates exceeding 2
inches per hour. This will support widely scattered to numerous
instances of flash flooding across this region. Despite recent dry
weather, the long-duration of the training convection across this
region should easily overcome these FFG values. While each
individual cell will move rather rapidly to the northeast across
this area, the high likelihood that multiple cells producing heavy
rainfall will move over any one location under the line of storms
will compound any flooding and rises in streams and creeks rather rapidly.

Urban flash flooding will be a significant concern as these storms
set up very near metro Memphis, though likely staying just south
and east of the city. Expect the southern and eastern suburbs to
be hard-hit with multiple inches of rain through the morning.

The line of training storms is likely to remain in roughly the
same place through the morning based on many of the CAMs guidance
into the early afternoon until both the upper level shortwave and
attendant surface cold front push through and shift the storms off
to the east. This discussion will be updated as the situation evolves.

Wegman

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

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

LAT...LON   36408824 36138749 35118829 34788860 34038936 
            31619205 31649320 32649244 33719163 34739068 
            36118922 
$$
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