AWUS01 KWNH 131633
FFGMPD
MSZ000-LAZ000-ARZ000-132130-

Mesoscale Precipitation Discussion 1154
NWS Weather Prediction Center College Park MD
1132 AM EST Wed Nov 13 2024

Areas affected...south-central/southeastern LA into southwestern
MS

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

Valid 131630Z - 132130Z

SUMMARY...Training and repeating of thunderstorms should maintain
at least localized flash flooding from south-central and
southeastern LA into southwestern MS. Localized rainfall rates of
2 to 3+ in/hr will remain possible, falling atop locations which
received heavy rain in recent days. Additional totals of 2 to 4
inches will be possible (perhaps locally higher) through 22Z, but
the coverage of these higher rainfall totals should remain
low/spotty.

DISCUSSION...Areas of training thunderstorms in and around the
Lafayette metro have resulted in numerous reports of 4-6 inches of
rain over the past 4-5 hours with hourly rainfall as high as 4
in/hr. Heavy rainfall has been focusing along an inverted trough
or weak frontal boundary extending northward from a weak/elongated
low located just south of Marsh Island with the coldest cloud tops
over southwestern MS into adjacent areas of LA at 16Z. 12Z
soundings from LCH and LIX combined with Layered PW Imagery from
CIRA showed the bulk of the nearly 2 inch precipitable water
values are focused below 700 mb, with a fair amount of dry air in
the middle and upper troposphere.

Over the next 3-6 hours, the elongated area of low pressure/shear
axis across LA is expected to slowly but steadily get pushed east
ahead of a large-scale 700-500 mb trough moving east across the
central/southern Plains. Surface to 850 mb convergence will shift
into the southwestern quadrant of MS and southeastern LA through
21Z where MLCAPE of 500-1500 J/kg is forecast to reside (highest
to south) via the latest RAP guidance. Areas of training
thunderstorms are expected to continue with 2 to 3+ in/hr rainfall
rates at times, overlapping with areas that received heavy rain
over the weekend and may remain hydrologically more sensitive to
runoff.

Farther east, a low level axis of convergence/leading edge of
moisture return to the south of an East Coast surface ridge has
been producing a few showers and thunderstorms. This area of
convection is likely to shift east as well in a mostly progressive
fashion, but an isolated threat for short term training could
result in urban flooding for the New Orleans metro over the next
few hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4tLj5AP-59ex4RZwax1shPABq6k0zjoqsPm_gIICJlTSMXmSSdewwAoW9g_QzwMRn-Li=
Em8Cr5v2lBAGXPU1O0pzBEM$  for graphic product...

ATTN...WFO...JAN...LCH...LIX...MEG...

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

LAT...LON   33859027 33688989 33368956 32838930 31428951=20
            30298983 29499014 29689133 30039181 30799201=20
            32179173 33329125 33839080=20

=3D =3D =3D
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