Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun Jun 22 2025
Valid 222000Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MIDWEST
TO PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS....
...SUMMARY...
Isolated to scattered thunderstorms are expected today across the
northern Plains and Upper Mississippi Valley, some of which could
produce large hail, damaging wind gusts and tornadoes. Storms
associated with severe gusts and hail may also develop across parts
of the southern and central Plains, and Northeast.
...20z Update Central/Northern Plains...
Current surface and satellite observations show strong heating
occurring from far eastern WY, into the NE panhandle within a
post-frontal upslope flow regime. As ascent from the primary trough
across the northern Rockies moves overhead, storm initiation appears
likely this afternoon. Weak destabilization, with moderate
deep-layer shear suggests a few supercells are likely with hail and
damaging winds the primary risk. A brief tornado is also possible
with the stronger surface-based supercells given strong low-level
veering. The MRGL and SLGT boundaries have been adjusted westward to
better align with expected storm initiation along the terrain and
stalled front. See MCD#1403 for additional short-term info.
To the north across eastern SD/ND and MN, the severe risk continues
largely as expected. Strong heating ahead of a surface low and warm
front will support scattered storm development this afternoon and
evening. Deep-layer shear will support supercells and clusters
capable of all severe hazards. Storms will continue eastward this
evening and overnight across northern MN with damaging gusts and
hail likely.
...Northeast...
In the wake of an earlier MCS, strong heating remains evident along
a remnant outflow boundary from eastern PA into southwestern NY
state. However, mid-level height rises and subsidence are evident in
visible/WV imagery and will continue to suppress convective
development over much of the region. An isolated storm or two
remains possible along the boundary through late this afternoon, but
more widespread convective coverage is unlikely. Should storms form,
a strong/severe wind gusts will be possible, in addition to sporadic
hail, given seasonably large buoyancy and steep mid-level lapse
rates. With decreased confidence in storm development/coverage, have
opted to remove the SLGT risk and continue with 5% wind/hail
probabilities.
..Lyons.. 06/22/2025
.PREV DISCUSSION... /ISSUED 1136 AM CDT Sun Jun 22 2025/
...Northern/Central Plains into the Upper Midwest...
A warm front extends northeast from a surface low over northern SD
across northern MN and east across the northern Great Lakes. This
warm front should lift north through the day, while a cold front
extends southwest of the surface low into northeast CO.
Thunderstorms over eastern ND/northwest MN have produced near severe
gusts as they continue to move northeast towards the international
border.
Redevelopment of thunderstorms is anticipated towards late afternoon
or early evening across eastern ND/western MN southward into eastern
SD as a weak mid-level perturbation lifts northeast across the area,
contributing large-scale ascent and weakening the capping inversion.
These storms will move east/northeast within a strongly unstable air
mass and include a mix of supercell and cluster modes with a risk
for large to very large hail initially, and transition into an
increasing wind threat with time. Tornado potential appears to be
greatest over northern MN, where low-level SRH will be maximized.
The potential for elevated, post-frontal thunderstorm development
across the NE Panhandle will exist later this afternoon/evening,
with storms moving east and posing a risk initially for severe hail.
The severe wind potential will increase with eastward extent as
storms congeal and tap greater surface instability farther east.
...Central/Southern High Plains...
Low-level moisture advection and related airmass destabilization
coupled with low-level convergence along the lee trough is expected
to result in thunderstorm development from eastern CO/western KS
through eastern NM and into far west TX. Vertical shear will be
modest, likely resulting in predominantly outflow-dominant storm
structures and the potential for damaging wind gusts. Some isolated
hail is also possible with the strongest/more persistent updrafts.
...Northeast...
Overall storm intensity along the western flank of outflow from the
long-lived MCS remains sub severe, and have narrowed the Marginal
and Slight Risk areas to along and immediately southwest of the
convective line. Substantial diurnal heating of a very moist air
mass, and 30-40 kts of effective shear, may support some severe
potential as storms move generally southward along the eastern
periphery of the mid-level ridge. Isolated to widely scattered
strong/severe wind gusts will be possible, in addition to isolated
hail reports given seasonably steep mid-level lapse rates.
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