900
AWUS01 KWNH 171143
FFGMPD
ALZ000-MSZ000-171742-

Mesoscale Precipitation Discussion 0281
NWS Weather Prediction Center College Park MD
742 AM EDT Fri May 17 2024

Areas affected...Central/Southern MS into Central/Southern AL

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

Valid 171142Z - 171742Z

SUMMARY...Heavy showers and thunderstorms will continue to develop
and expand in coverage over the next few hours. Cell-training and
high rainfall rates will likely lead to areas of flash flooding.

DISCUSSION...The latest GOES-16 IR satellite imagery shows a
developing and expanding axis of cooling convective cloud tops in
a west-southwest to east-northeast fashion across south-central MS
and into parts of south-central AL. The convection is developing
along an elevated instability axis across the region along with a
corridor of stronger 925/850 mb moisture convergence which is
associated with the broader south to southwest low-level jet
across the region which is on the order of 30 to 40+ kts.

PWs across the region of 1.75 to 2.0 inches and MUCAPE values of
around 1500 J/kg coupled with a corridor of stronger shear values
should work to yield impressive rainfall rates that may reach 2 to
2.5 inches/hour with the stronger convective cores. Additional
overall expansion of convection in an elongated and locally
training fashion is expected this morning, and this will favor
excessive rainfall totals.

The early morning guidance collectively is not doing a good job of
handling the current convective activity, but the HRRR guidance is
generally the closest and suggests upscale growth across areas of
south-central MS through south-central AL going through the early
afternoon hours. This will be driven by an expected increase in
larger scale forcing associated with stronger upper-level jet
dynamics arriving in conjunction with the favorable thermodynamic
environment.

Given the cell-training concerns and high rainfall rates, some
additional rainfall amounts of 3 to 5 inches will be possible by
1800Z. Given the generally moist antecedent conditions that are in
place, at least scattered instances of flash flooding will be
likely over the next several hours.

Orrison

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

ATTN...WFO...BMX...JAN...LIX...MOB...

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

LAT...LON   32988618 32528562 32008620 31488827 31209074
            31619139 32229067 32938802