ACUS01 KWNS 021627
SWODY1
SPC AC 021626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Wed Apr 02 2025

Valid 021630Z - 031200Z

...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO
EARLY TONIGHT FROM EASTERN ARKANSAS INTO THE LOWER OHIO VALLEY...

...SUMMARY...
A tornado outbreak is expected this afternoon into early tonight
from parts of the lower Mississippi Valley into the Mid-South and
lower Ohio Valley. Numerous tornadoes, along with multiple EF3+
tornadoes, appear likely. In addition, tornadoes, significant severe
wind gusts, and large hail to very large hail will be possible
across a broad area from north Texas northeastward to the southern
Great Lakes.

...OH/MS Valleys through tonight...
In response to an ejecting midlevel trough and associated 110 kt 500
mb jet streak, a surface cyclone will develop northeastward from IA
to Lake Superior.  Severe storms are ongoing in a broken band from
west central IL across MO into northwest AR/eastern OK, which
demarcates the effective frontal zone and focus for additional storm
development through the afternoon.  The warm sector in advance of
these storms is characterized by boundary-layer dewpoints in the
low-mid 60s across IL/MO and near 70 F from the Ark-La-Tex into the
Ark-La-Miss.  Low-level moisture will continue to spread northward
through the day on 50-70 kt flow 1-2 km above ground level, and
surface heating in cloud breaks will boost MLCAPE into the 2000-3000
J/kg range with only weak convective inhibition through the
afternoon.  The northern extent of the surface warm sector
(northeast IL across northern IN/northwest OH/southern Lower MI)
will be modulated by ongoing convection.

The primary jet streak/cyclone will be displaced northwest of the
unstable warm sector, though flow will remain strong in the warm
sector with long hodographs and substantial low-level
shear/hodograph curvature.  Convective mode is expected to be
somewhat messy with embedded supercells within an increasingly
extensive band of storms through the afternoon/evening.  Convective
inhibition will be sufficiently weak to support some potential for a
few supercells ahead of the band in the open warm sector.  The
tornado threat will be maximized for the more discrete storms within
or ahead of the main band, where a few intense (EF3+) tornadoes will
be possible.  Otherwise, evolution into an extensive squall line is
expected with an accompanying threat for damaging winds (60-80 mph)
and occasional large hail (1.5-2.5 inches in diameter - especially
with persistent supercells).

Overnight, the northern portion of the squall line will eventually
move east of the more unstable warm sector and weaken from OH into
western PA.  The southern portion of the convective band is expected
to pivot gradually to a more WSW-ENE orientation favoring training
convection along and atop the conglomerate cold pool.

...North TX/southeast OK this evening through Thursday morning...
In the wake of the ejecting IA-Lake Superior jet streak, midlevel
flow will tend to amplify/back with time over TX, downstream of the
amplifying large-scale trough over the Southwest.  This will
contribute to weak cyclogenesis across northwest TX along the
residual baroclinic zone, and a strengthening warm advection regime
along/north of the boundary tonight.  The open warm sector will
likely remain capped (per the warm elevated mixed layer observed
this morning over TX), but the environment will favor elevated
supercells to the cool side of the boundary.  Very large hail in
excess of 2 inches in diameter and isolated severe gusts will be the
main threats with these elevated storms overnight.

..Thompson/Jirak.. 04/02/2025

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