SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Sun Mar 30 2025
Valid 301200Z - 311200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH TONIGHT ACROSS MUCH OF SERN IL...IN...WRN AND CENTRAL
OH...SERN MO...CNTRL AND ERN AR...KY...TN...NWRN AL...NRN AND CNTRL
MS...NRN LA...NERN TX...
...SUMMARY...
Thunderstorm development is likely to become widespread across the
Ohio Valley southwestward through the Tennessee and lower
Mississippi Valleys this afternoon into tonight. Initially, this
activity will pose a risk for large large hail. A few tornadoes are
also possible, before damaging wind gusts become the more prominent
potential severe hazard this evening into tonight.
...Discussion...
To the north of an intense, zonal jet across the southern
mid-latitude eastern Pacific, a significant mid-level low is
forecast to progress slowly eastward across the northeastern
Pacific, toward the Pacific Northwest coast, accompanied by a deep
occluded surface cyclone. This has been preceded inland by a series
of less prominent perturbations, a couple of which may be
consolidating into more notable larger-scale mid-level troughing to
the east-northeast of the southern Rockies.
Models continue to indicate that this evolving mid-level wave will
accelerate into a broadly confluent regime across the Ohio Valley
through lower Great Lakes region, between a significant short wave
trough digging across Manitoba/Ontario and downstream ridging
overspreading the St. Lawrence Valley/Northeast. Models suggest
that an associated surface low, likely initially over eastern Iowa
at the outset of the period, will continue an east-northeastward
migration into and across the Great Lakes, but it may not undergo
substantive further deepening until late this afternoon into tonight
across the lower Great Lakes into southeastern Ontario/southwestern
Quebec.
Trailing this cyclone, a notable cold front is forecast to progress
southeastward through the southern Great Plains, and eastward
through the mid/lower Mississippi Valley and middle Ohio Valley by
late tonight. The front will continue to be preceded by a
moistening southerly return flow, which may include surface dew
points increasing through the lower/mid 60s F as far north as
southern portions of the Great Lakes region, at least initially
beneath a remnant plume of elevated mixed-layer air emerging from
the high plains.
...Ohio Valley into southeastern Great Plains...
Models suggest that thermodynamic profiles will become supportive of
sizable conditional and convective instability, with a fairly broad
reservoir of CAPE in excess of 2000 J/kg evolving across the
southeastern Great Plains through lower Mississippi Valley, as far
north as the confluence with the Ohio River by late this afternoon.
Farther north, mixed-layer CAPE is likely to increase in excess of
1000 J/kg during the day, within a narrower corridor
across/north-northeast of the middle Mississippi Valley, where
mid/upper forcing for ascent is likely to initiate intensifying
thunderstorm activity by early to mid afternoon. This may include a
few supercells posing a risk for large hail and potential for a
couple of tornadoes, before convection tends to gradually
consolidate and grow upscale, accompanied by increasing risk for
damaging wind gusts.
This initial activity may be maintained northeastward and eastward
through much of the Ohio Valley by late this evening, before tending
to weaken while acquiring less unstable inflow. Meanwhile,
subsequent initiation of storms is likely southwestward ahead of the
cold front, across the lower Ohio Valley/Mid South toward the
Ark-La-Tex later this afternoon into this evening. It appears
possible that this may coincide with strengthening
lower/mid-tropospheric flow accompanying a trailing jet streak. And
a period of intensifying discrete supercell development might not be
out of the question, before activity tends to grow upscale into one
or more organizing clusters. Depending on how quickly this occurs,
there may be a conditional risk for a couple of strong tornadoes,
before damaging straight line winds, and perhaps brief tornadoes
with evolving near-surface meso vortices, becomes the more prominent
hazard southeastward into the Gulf Coast states overnight.
...Florida Peninsula vicinity...
HREF and NCEP SREF guidance indicates rather high probabilities for
thunderstorm development, as weak mid-level troughing overspreads
the peninsula today. Beneath modestly cool mid-level temperatures,
it appears that boundary-layer moisture will support moderate CAPE,
and thermodynamic profiles may become conducive to a few stronger
storms with small, melting hail contributing to potential for
localized damaging downbursts.
..Kerr/Weinman.. 03/30/2025
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