ACUS02 KWNS 030552
SWODY2
SPC AC 030550
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1150 PM CST Sun Mar 02 2025
Valid 041200Z - 051200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TUESDAY INTO
TUESDAY EVENING ACROSS SOUTHERN ARKANSAS...MUCH OF NORTHERN AND
CENTRAL LOUISIANA AND CENTRAL/SOUTHERN MISSISSIPPI...
...SUMMARY...
One or two organized lines or clusters of thunderstorms, and perhaps
a few supercells, will pose a risk for damaging wind gusts, a few
tornadoes and hail, primarily across parts of the lower Mississippi
Valley into the Southeast, Tuesday through Tuesday night.
...Discussion...
Model output remains varied concerning sub-synoptic developments
into and through this period. However, better consensus is evident
among the various model ensemble output concerning the large-scale
pattern evolution across the eastern Pacific into North America.
Within this regime, a significant upper trough, now inland of the
Pacific coast, is forecast to progress east of the Great Plains
through Mississippi Valley Tuesday through Tuesday night,
accompanied by continuing strong cyclogenesis.
Models generally indicate that the center of the evolving broad and
deep surface cyclone will migrate from western Kansas through
northern Illinois during this period. In the wake of the cyclone, a substantive cold front is forecast to surge southeastward across the
southern Great Plains into northwestern Gulf coast and lower
Mississippi Valley by 12Z Wednesday. This may be preceded by a more
modest Pacific cold front across the southern Great Plains at the
outset of the period, and potentially cool/dry air across/east of
the lower Mississippi Valley, associated with a surface ridge
shifting off the Atlantic Seaboard, in the wake of de-amplifying
large-scale mid/upper troughing.
A southerly return flow off a modifying boundary-layer over the
western Gulf Basin is likely to be ongoing early Tuesday across
eastern Texas toward the lower Missouri Valley, before shifting
eastward across and east of the lower Mississippi Valley. In
response to the evolution and progression of the cyclone, models
suggest that better low-level moisture return from the Gulf will
probably become cut off across the eastern Gulf Coast region by late
Tuesday night.
Across and northeast of a low-level baroclinic zone, initially
extending across the Ark-La-Tex vicinity southeastward through
southern portions of the lower Mississippi Valley, the Gulf moisture
return will initially become elevated above a residual cool/stable surface-based layer. However, the NAM and Rapid Refresh output
still suggest that this boundary will become more diffuse while
developing eastward through the day.
Regardless, most model output remains suggestive that elevated
and/or closer to surface-based destabilization, and large-scale
ascent associated with the cyclone, will become sufficient to
support extensive convective development across the interior U.S.
Tuesday through Tuesday night, and a fairly broad area with at least
a conditional risk for severe storms.
...Lower Mississippi Valley into Southeast...
The remnant, though becoming increasingly diffuse, baroclinic zone
across the lower Mississippi Valley, might become the primary
initial focus for intense thunderstorm development during this
period. As the environment destabilizes more rapidly to the
southwest of this boundary, and low-level warm advection along it
contributes to large-scale ascent accompanying a short wave
perturbation overspreading the lower Mississippi Valley, conditions
may become conducive to the evolution of an organizing storm
cluster. This may be preceded by a couple of discrete supercells.
Given the strength of the deep-layer mean wind fields, which may
include a belt of south-southwesterly flow in the 850-500 mb layer
on the order of 60-100 kt overspreading Louisiana and Mississippi
during the day, there appears at least conditional potential for
supercells capable of producing strong tornadoes. With the
strongest wind fields generally forecast in the inflow layer of the
convective development, the extent of the damaging wind potential
remains more unclear, particularly with any evolving cluster
developing along/above a maturing cold pool
Much will also depend on the extent to which near-surface
thermodynamic profiles are able to destabilize in advance of the
large-scale forcing. Both the latest Rapid Refresh and NAM forecast
soundings suggest this may be an issue, and potential mitigating
factor with regard to the severe wind and tornado potential,
particularly overnight east of the lower Mississippi Valley into the
eastern Gulf Coast states.
..Kerr.. 03/03/2025
$$
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