374
AWUS01 KWNH 171708
FFGMPD
MSZ000-LAZ000-172305-

Mesoscale Precipitation Discussion 0453
NWS Weather Prediction Center College Park MD
107 PM EDT Mon Jun 17 2024

Areas affected...South-Central to Southeast LA...Far Southwest MS

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

Valid 171705Z - 172305Z

SUMMARY...Locally slow-moving and occasional back-building of
showers and thunderstorms with very heavy rainfall rates may
result in some flash flooding concerns going through the afternoon
hours.

DISCUSSION...The midday GOES-E Day Cloud Phase RGB in conjunction
with dual-pol radar shows an area of convection generally tending
to grow in coverage across areas of south-central to southeast LA,
and far southwest MS. The activity is being facilitated by
increasing low-level convergence along the leading edge of an
inverted surface trough crossing the central Gulf Coast region.

This coupled with increasing boundary layer instability and very
moist southeast flow coming in off the Gulf of Mexico will likely
further encourage an expansion of convection over the next few
hours. Additionally, the upper-level flow pattern is becoming
increasingly diffluent aloft in connection with the area of
disturbed weather over the central and southern Gulf of Mexico.

MLCAPE values of 1500+ J/kg with PWs of 2.0 to 2.25 inches will
drive very heavy rainfall rates with the organizing clusters of
convection. Rainfall rates with the stronger storms are forecast
to locally reach 2 to 2.5 inches/hour, and with a set-up that is
conducive for back-building and repeating convective cells, some
localized storm totals going through late this afternoon may reach
3 to 5 inches, and this is consistent with the 12Z HREF guidance.

Some isolated to widely scattered instances of flash flooding will
be possible, and this will include a localized urban flash flood
concern.

Orrison

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

ATTN...WFO...JAN...LCH...LIX...SHV...

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

LAT...LON   31889179 31819089 31168957 30488929 29958943
            29738967 29519063 29739180 30219264 30899278
            31449255