SPC Jun 22, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1136 AM CDT Sun Jun 22 2025

Valid 221630Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE CENTRAL/SOUTHERN HIGH PLAINS AND OVER PORTIONS OF THE
NORTHEAST...

...SUMMARY...
Isolated to scattered thunderstorms are expected to develop 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 Northeast, and in the southern and central Plains.

...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.

..Bunting/Squitieri.. 06/22/2025

StormPrep