Graphic for MPD #0114

Mesoscale Precipitation Discussion 0114
NWS Weather Prediction Center College Park MD
1201 AM EDT Tue Mar 26 2024

Areas affected...Portions of Central/Eastern LA through
Central/Southern MS and Western AL

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

Valid 260400Z - 261000Z

SUMMARY...Additional isolated to widely scattered instances of
flash flooding will be possible heading through the overnight
hours from a well-organized line of showers and thunderstorms with
very heavy rainfall rates.

DISCUSSION...The latest radar imagery shows a broken QLCS oriented
in a southwest to northeast fashion from portions of central LA
through central MS. The northern portion of this convective line,
generally near and northeast of Jackson, MS, has been tending to
bow a bit more progressively off to the east which has tended to
mitigate the rainfall totals somewhat despite the very organized
structure of the convection.

However, the portion of the line that involves areas of central LA
into at least southwest MS has been slower moving and over the
last 1 to 2 hours has begun to exhibit some short-term training
character. This is occurring as the convection becomes aligned
more parallel to the deeper layer southwest flow out ahead of an
upper-level trough moving into the MS Valley. There is a fair
amount of instability lurking out ahead of the southwest portion
of the QLCS across eastern LA and southwest MS where MLCAPE values
are still on the order of 1000 to 1500+ J/kg. This coupled with a
strong and convergent low-level jet of 50 to 60 kts and 50+ kts of
effective bulk shear is likely to support QLCS sustenance over the
next several hours that will be capable of producing very heavy
rainfall rates.

The PWs have risen to locally 1.5 to 1.75 inches, and this coupled
with the favorable thermodynamic environment and strong
shear-enhanced updrafts should help support rainfall rates that
occasionally reach or exceed 2"/hour. The latest 00Z HREF guidance
appears to be under doing the convective organization of the
strong cluster of cells south of Natchez, MS and north of New
Roads, LA. This activity in particular is rather slow-moving, but
is exhibiting some very cold overshooting top activity within the
last hour, and is likely producing rainfall rates of 2.0 to
2.5"/hour.

The larger scale convective threat should overall continue to
advance downstream across central and southern MS and will
eventually get into areas of western AL. The southwest flank of
the line that still impacts portions of central/eastern LA and
southwest MS will generally have the greater cell-training
potential. Some rainfall totals of 2 to 4 inches with isolated
heavier amounts will be possible where this occurs.

Additional isolated to widely scattered instances of flash
flooding will be possible as a result, and this will include the
more sensitive urban locations where runoff will be more
pronounced.

Orrison

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

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

LAT...LON   33798801 33508751 32608764 31368871 30588956
            30379000 30249075 30409141 30739167 31049168
            31549131 33168966 33678888
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Last Updated: 1201 AM EDT Tue Mar 26 2024