SPC Jun 23, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0721 AM CDT Mon Jun 23 2025

Valid 231300Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS INTO THE UPPER MS VALLEY AND UPPER GREAT LAKES...

...SUMMARY...
Storms with isolated severe wind gusts and hail will be possible
today from the southern and central Plains northeastward into the
Great Lakes.

...Central Plains into the Upper MS Valley and Upper Great Lakes...
Early-morning satellite imagery shows a shortwave trough progressing
through ND and southern SK/MB. Surface analysis places the low
associated with this shortwave over far northwestern ON, with an
attendant cold front arcing from this low through the MN arrowhead
and back through south-central MN, northwest IA,
eastern/south-central NE to another low in northwest KS. Showers and
thunderstorms are ongoing along this frontal zone from northeast NE
into southern MN. 

Expectation is for the shortwave trough to continue northeastward
through far northwest ON throughout the day, with the primary
surface low also tracking northeastward just ahead of its parent
shortwave. Gradual eastward/southeastward progress of the cold front
is anticipated, although its forward progression will slow with
time, particularly from the Mid MO Valley southwestward into the
southern High Plains. A warm and moist airmass exists ahead of this
front, with temperatures expected to reach the mid 80s to low 90s
amid dewpoints in the upper 60s to low 70s. These conditions will
result in strong buoyancy and little to no convective inhibition
along much of the front by 21Z. 

Large-scale forcing for ascent will be negligible, but persist
low-level convergence should be enough to initiate deep convection,
with numerous to widespread thunderstorms anticipated. The stronger
deep-layer vertical shear will lag behind the front across much of
the region, but steep low-level lapse rates and ample moisture
should still result in sporadic damaging gusts. There will be better
overlap between the shear and buoyancy from WI into MI, and there is
some chance for one or more forward-propagating line segments in
this area. Some isolated hail is possible within the more robust
early-stage storms. Storm mergers could also result in updrafts
briefly becoming strong enough to produce hail.

...Southern and Central High Plains...
Numerous thunderstorms are expected to develop during the afternoon
amid persistent low-level convergence within the warm, moist, and
weakly sheared airmass over the region. The lack of stronger shear
will result in largely outflow-dominant storm structures. Given the
high cloud bases and steep low-level lapse rates, damaging gusts are
possible with the stronger storms.  

...Northern ME...  
A convectively augmented vorticity maximum currently over
northeastern ON is forecast progress eastward through southern QC
and into the Canadian Maritimes during the period. Showers and
thunderstorms will accompany this vorticity max, with a few stronger
storms potentially glancing northern ME this evening. Moderately low
to mid-level westerly flow will support the threat for some damaging
gusts as these storms move through the region.

...Southeast...
Scattered to numerous diurnally driven thunderstorm are expected
across the region today. Shear will be weak, with a multicellular
pulse mode anticipated. Given the ample moisture and likelihood of
storm interactions, a few strong, water-loaded downbursts are
possible. Limited coverage precludes the need for any severe
probabilities.

..Mosier/Leitman.. 06/23/2025

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