SPC AC 301621
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Sun Mar 30 2025
Valid 301630Z - 311200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
THE LOWER/MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY AND SOUTHERN
GREAT LAKES...
...SUMMARY...
Numerous severe thunderstorms are expected through tonight across a
broad portion of the Southeast and lower/mid Mississippi Valley into
the Ohio Valley and southern Great Lakes. Multiple swaths of
widespread damaging winds appear likely. Large to very large hail
and several tornadoes will also occur with supercells. A few of
these tornadoes could be strong.
...Synopsis...
Water-vapor imagery late this morning shows a lead mid-level
shortwave trough moving quickly northeastward across MO, while an
upstream disturbance over the TX Panhandle/western OK rounds the
base of a larger-scale trough over the central U.S. Surface
analysis places a cyclone near the IA/IL/WI border with a trailing
cold front south-southwestward through the lower MO Valley and into
eastern OK and north TX. This front will push east through the OH
Valley and into the lower MS Valley by early Monday morning and
focus thunderstorm development.
...Midwest/Ohio Valley to the Great Lakes...
Visible-satellite imagery shows cloud breaks to the immediate east
of the lead mid-level disturbance as a moist/warm conveyor (40-kt
southwesterly LLJ) maintains a fetch of seasonably rich moisture
into the region. Additional thinning cloud cover and heating
through the early to mid afternoon will lead to thunderstorms
developing and intensifying. A belt of 50-80 kt 500-mb flow will
overspread the destabilizing airmass and yield ample deep-layer
shear for organized convection.
The stronger early storms will favor supercell and banded linear
modes, with the supercells posing a threat for large to very large
hail (around 1.5-2.5 inch diameter) given the presence of steep
mid-level lapse rates and favorable deep-layer shear. Meridional
upper-level flow from I-70 northward will favor a quicker transition
to linear structures compared to farther south/southwest, where
hodographs will promote a longer window of opportunity for cellular
(discrete and clusters) storm modes. The tornado risk will be
greatest with quasi-discrete supercells (potentially a few strong
tornadoes) near and south of the OH River, but some tornado threat
will probably develop with a squall line as it matures through the
afternoon/evening. As storm coverage increases, multiple swaths of
numerous to potentially widespread severe/damaging winds appear
likely as one or more clusters moves quickly east-northeastward over
the OH Valley and southern Lower MI. The threat for damaging winds
and tornadoes should continue this evening into the overnight hours,
until convection outpaces the low-level moisture return and
eventually weakens over the upper OH Valley and central
Appalachians.
...Central/East Texas into the Lower/Mid Mississippi
Valley/Mid-South and Southeast...
Strong destabilization is anticipated across the Ark-La-Tex east and
northeastward into the Mid South. Rich low-level moisture (mid to
upper 60s to around 70 deg F dewpoints) will stream northward across
TX ahead of the dryline, and the lower/mid MS Valley and Southeast
ahead of the cold front. Model guidance continues to indicate rapid
and intense thunderstorm development during the afternoon from parts
of north/east TX northeastward into AR. Supercells are expected
initially, with 40-50+ kt of deep-layer shear supporting robust
updraft organization and rotation. A favorable setup exists for
large to very large hail with the stronger supercells.
It appears the greatest risk for several tornadoes will focus
over parts of the Mid-South from eastern AR into western TN on the
southern periphery of an intensification of 850-mb flow towards
evening. Forecast soundings show moderate to locally strong
buoyancy (2000-3000 J/kg MLCAPE) on the northern rim of 66-68 deg F
dewpoints, and co-located with strong southwesterly flow veering to
westerly by early evening. It is during the 22-04 UTC period in
which forecast hodographs enlarge in the low levels and become more
favorable for discrete supercells. The strong tornado risk may
maximize within this corridor from parts of eastern AR eastward into
western and perhaps Middle TN during the evening. Additional severe
storms are probable farther south as activity from the Ark-La-Tex
moves east into the lower MS Valley and central Gulf Coast states
during the late afternoon into tonight. In addition to large to
very large hail, damaging gusts and a tornado risk will likely
accompany the stronger storms with a gradual lessening in overall
coverage and intensity during the late night.
...Florida Peninsula...
A weak mid-level perturbation will move eastward over FL this
afternoon. Modestly enhanced winds aloft, and a veering profile
with height through mid levels, should support sufficient deep-layer
shear for strong to severe multicells. The stronger diurnally
driven storms may be capable of severe hail and damaging winds.
..Smith/Moore.. 03/30/2025
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