SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1246 AM CDT Sat Mar 29 2025
Valid 291200Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
THE OVERNIGHT HOURS ACROSS NORTHERN OKLAHOMA AND SOUTHEASTERN KANSAS
INTO WESTERN MISSOURI...
...SUMMARY...
Widely scattered severe thunderstorms are possible across parts of
the central and southern Great Plains into middle Mississippi Valley
today through tonight. This may include an organizing cluster of
storms across parts of northern Oklahoma and southeastern Kansas
through western Missouri this evening into the overnight hours.
...Discussion...
Downstream of a blocked regime, including an increasingly prominent
mid-level high centered over the western Aleutians, models indicate
that a broad, deep mid-level low will continue to evolve across the
northeastern Pacific. To the south of this feature, mid-level flow
is forecast to intensify in a westerly belt across the southern
mid-latitudes, toward the central and southern California coast.
This will be preceded inland by a number of weaker perturbations
across the southern Great Basin and Rockies, through the Great
Plains, where at least a couple may gradually begin to consolidate
into larger-scale troughing by 12Z Sunday.
A sub-1000 mb low has already formed within surface troughing to the
lee of the Colorado Rockies. However, models indicate little, if
any, further deepening through this period. The impact of
seasonably cold air, now nosing southward to the lee of the northern
Rockies, remains unclear. But guidance generally indicates that the
primary low will either migrate across or reform east-northeast of
the central Great Plains into Iowa by late tonight, with the
trailing cold front surging across the central Great Plains.
It appears that this will be preceded by a moistening southerly
return flow, which probably will include surface dew points rising
through the 60s across much of the lower southern into central Great
Plains by early this evening, and into portions of the Upper Midwest
by early Sunday. Models indicate that this will occur beneath a
narrow plume of elevated mixed-layer air slowly spreading across and
east of the Great Plains into Mississippi Valley.
...Southern Great Plains toward the Upper Midwest...
By late this afternoon, the low-level moisture return, coupled with
insolation beneath the elevated mixed-layer, may contribute to CAPE
in excess of 1000 J/kg as the leading edge of mid-level cooling
overspreads portions of the central Great Plains into mid/lower
Missouri Valley vicinity. This is forecast to accompany an initial
short wave perturbation, though the stronger mid/upper forcing for
ascent may remain largely focused above cold surface-based air to
the northwest and north of the surface low. Still, the initiation
of isolated to widely scattered thunderstorm development along the
dryline may not be entirely out of the question, particularly across
north central Kansas, before propagating east-northeastward within
an environment conducive for supercell development.
There has been a more consistent signal evident in model output
concerning thunderstorm initiation with forcing accompanying a
trailing perturbation likely to impact the vicinity of the cold
front and dryline intersection by early this evening. It appears
that this will probably be focused across northwestern Oklahoma,
perhaps as far north as the Interstate 35 corridor of south central
Kansas and as far south as northwestern portions of the Greater
Oklahoma City area, before spreading east-northeastward toward the
lower Missouri Valley/Ozark Plateau through early Sunday.
This may coincide with better boundary-layer moisture return
(include surface dew points increasing into the mid 60s F+, which
may contribute to CAPE in excess of 2000 J/kg) and strengthening
low-level and deep-layer shear, which is likely to become supportive
of a few supercells, at least initially. Activity may gradually
grow upscale into an organizing cluster, accompanied by potential
for large hail, damaging wind gusts, and perhaps a tornado or two.
Farther south, the risk for severe weather appears to remain largely
conditional. HREF guidance and other model output suggest only low
probability for thunderstorm initiation overnight, roughly across
parts of the Edwards Plateau into central Texas, where moderate
potential boundary-layer instability may remain capped by warm, dry
air in the lower/mid-troposphere.
..Kerr/Weinman.. 03/29/2025
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