179
AWUS01 KWNH 131427
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-131826-

Mesoscale Precipitation Discussion 0264
NWS Weather Prediction Center College Park MD
1027 AM EDT Mon May 13 2024

Areas affected...southeastern Louisiana, southern Mississippi,
southern Alabama, Florida Panhandle

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

Valid 131426Z - 131826Z

Summary...Heavy rain/localized flash flooding remains likely with
an elongated convective complex intensifying along/north of the
I-10/12 corridor.  Multiple hours of 1-2.5 inch/hr rain rates are
expected in parts of the discussion area.

Discussion...Convective trends indicate intensification of an
ongoing MCS located from near Mobile, AL to near Hammond, LA.
Mesoscale organization along sections of this MCS has enabled a
subtle southward translation of the axis of heaviest rain with the
complex, with 2 inch/hr rain rates now being estimated per MRMS
near/north of Mobile and areas of 1-2 inch/hr rates noted near
Hammond.  The complex is located on the nose of robust low-level
flow (20-30 knots at 850mb), and individual cores were propagating
closer to strong surface-based instability (2500 J/kg MLCAPE),
indicating that storms were likely becoming surface-based with
time.  The orientation of the MCS (parallel to flow aloft) was
allowing for convective training, supporting a 2-3 hour period of
1+ inch/hr rain rates.  These rates are likely to cause at least
localized flash flood issues near low-lying, urbanized land
surfaces.

The MCS is likely to continue to produce heavy rainfall along its
trek across coastal areas of LA/MS/AL and the Florida Panhandle
over the next 3-5 hours.  FFGs are relatively high (3-4 inch/hr
thresholds) across the discussion area, further suggesting
isolated flash flood potential where prolonged rainfall can fall
in urban/low-lying areas.  A temporary reprieve in the heavy
rainfall is expected for a few hours on the western flank of the
MCS, although additional rainfall is likely to develop with
evolving convection well upstream (south/southwest Texas) later
today/this afternoon.

Cook

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

ATTN...WFO...JAN...LIX...MOB...TAE...

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

LAT...LON   31378826 31338665 30978522 30218449 29728456
            29668538 29868823 29808987 30269070 30959040
            31158968