Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0356 AM CDT Tue Jun 23 2026
Valid 231200Z - 241200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE CENTRAL HIGH PLAINS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE MID ATLANTIC...
CORRECTED FOR TEXT
...SUMMARY...
Severe storms capable of 2+ inch diameter hail, 75+ mph gusts, and
isolated tornadoes are expected from the central High Plains into
parts of the central and southern Plains today into tonight.
Damaging gusts and perhaps a brief tornado may occur with storms
along the Mid-Atlantic. Scattered storms capable of isolated severe
wind/hail are possible across the northern Plains into the upper
Mississippi Valley.
...Synopsis...
A mid-level trough will impinge on the Eastern Seaboard while upper
ridging builds over the western into central CONUS today. Multiple
mid-level impulses are poised to traverse the upper ridge,
supporting at least scattered thunderstorm development in multiple
rounds across the Plains. These rounds of storms will encompass the
entire period (12Z Tuesday morning through 12Z Wednesday morning),
resulting in a complex forecast. Nonetheless, stronger flow aloft
associated with the ridge will advect an EML atop seasonal low-level
moisture, resulting in enough buoyancy and vertical wind shear to
support an appreciable severe threat, especially over the central
High Plains. Otherwise, a cold front approaching the East Coast will
support a line of severe thunderstorms over the Mid-Atlantic.
...Portions of the central High Plains...
By afternoon peak heating, upslope flow beneath a glancing mid-level
impulse will support the initiation of at least isolated storms.
These storms will develop atop a relatively mixed boundary layer and
surface dewpoints approaching 60 F, overspread by 9 C/km mid-level
lapse rates, resulting in moderate to locally strong buoyancy (i.e.
3000+ J/kg MLCAPE). Strong vertical wind shear will also be in
place, with 50 kts of effective bulk shear driven by elongated
hodographs with modest low-level curvature. Supercells will be the
primary storm mode, accompanied by a threat for all hazards. Given
the potential for a mixed boundary layer, intense gusts well
exceeding 75 mph will be possible, in addition to hailstones
potentially reaching the 2-3.5 inch range. Any supercells that can
ingest terrain-induced low-level vertical vorticity may be
accompanied by a landspout/hybrid tornado threat.
...Portions of the central and southern Plains...
A surface boundary currently resides along the Red River, with
thunderstorms developing all along this boundary from the TX
Panhandle to central MS. At the start of the forecast period (12Z
Tuesday), an established low-level jet will be in the process of
transporting a moist low-level airmass northward, perhaps
encouraging northward movement of the surface boundary as well.
However, an MCS may develop somewhere along the KS/OK border at the
start of the period along an elevated boundary, which will drift
southeastward through the late morning/early afternoon hours. The
evolution of this MCS and interacting convection with the
aforementioned surface boundary introduces considerable uncertainty
to the forecast, especially for late afternoon/early evening storms.
If the MCS and merging surface boundary convection linger over the
southern Plains through the day, later severe potential may be
reduced. However, if convection can exit the Plains or somehow
dissipate by late morning/early afternoon, enough destabilization
may take place for an evening severe threat. Should the later
scenario unfold, convective initiation over the southern High Plains
may result in severe hail/wind producing supercells merging into a
cold-pool driven MCS, which in turn may produce a severe wind swath
with 75+ mph gusts. Given so much uncertainty with the details of
this forecast, a broad area of 15 percent/CIG1 probabilities were
introduced for portions of the central and southern Plains.
Considerable adjustments to this forecast (upgrades or probabilities
removal) may be needed depending on convective and subsequent
modified environmental evolution through the first half of the
period.
...Parts of the Northern Plains...
Cold temperatures aloft and 8+ C/km mid-level lapse rates will
accompany the passage of an upper low over parts of the northern
Plains into the Upper MS Valley. By afternoon peak heating,
thunderstorms initiating along the periphery of the upper low, amid
a belt of stronger flow aloft (driving elongated hodographs) will
support multicells and perhaps transient supercells capable of
isolated severe wind and hail.
...Mid-Atlantic...
By late morning into early afternoon, surface temperatures warming
into the 80s F amid 70+ F dewpoints will yield over 2000 J/kg
MLCAPE, but distributed through tall/thin profiles given poor (5-6
C/km) mid-level lapse rates. Nearly unidirectional tropospheric wind
profiles will yield nearly 40 kts of effective (speed) shear, which
will favor multicellular development and ultimately a squall line
along/ahead of the cold front. Damaging gusts are expected to be the
main threat, though a brief tornado may also occur wherever locally
backed near-surface winds may be realized.
..Squitieri/Halbert.. 06/23/2026
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