Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue May 12 2026
Valid 122000Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE GREAT LAKES...CENTRAL PLAINS AND FLORIDA...
...SUMMARY...
Severe storms remain possible across parts of the Florida Peninsula
today, and potentially from southeast Kansas into parts of the Great
Lakes late this afternoon and early evening.
...20z Update Great Lakes...
Afternoon visible imagery shows the cold core of an upper-level
trough beginning to impinging on modest low-level moisture south of
a stalled front near the MI/WI border. While moisture and resulting
buoyancy remain very limited (200-300 J/kg MUCAPE), steep mid-level
lapse rates and continued heating should support enough
destabilization for a few storms this afternoon and evening. Hail is
possible, especially with any storms elevated above the surface
given fairly strong mid-level flow. Have adjusted 5% hail
probabilities northward toward the warm front across the MI/WI
border.
...FL...
Numerous storms are ongoing this afternoon south of an east-west
oriented baroclinic zone across the FL Peninsula. To the south, the
environment remains moderately unstable and sheared, which has
supported a few organized clusters and supercells so far. Hail,
damaging winds, and a brief tornado remain possible with the
strongest storms as the boundary is forecast to sag southward
through tonight. Have removed severe probabilities and trimmed
thunder behind the boundary where the air mass has stabilized.
Otherwise, the prior outlooks remains valid with only minor
adjustments. See the previous discussion for more information.
..Lyons.. 05/12/2026
.PREV DISCUSSION... /ISSUED 1127 AM CDT Tue May 12 2026/
...Florida...
A very moist airmass is in place across the FL Peninsula today, with
surface observations showing dewpoints in the low to mid 70s.
Mesoanalysis estimates MLCAPE is at or above 1500 J/kg for much of
the peninsula already. A shortwave trough is currently moving into
the central Gulf Coast vicinity, with continued
eastward/southeastward progress expected throughout the day. The
prevailing buoyancy coupled with ascent attendant to this wave will
result in scattered to numerous thunderstorms. Low-level flow is
generally weak, but the shift from low-level easterly winds to
moderate southwesterly aloft is supporting moderate deep-layer
vertical shear. Some increased shear is possible in the vicinity of
the east-coast sea-breeze, with the strongest storms anticipated
near this boundary as a result. The overall expectation is for some
organized multicells and a few supercells, posing a risk of damaging
wind gusts and hail, particularly across the east-central portions
of the peninsula.
...Upper Midwest through the Mid MO Valley into southeast
KS/northeast OK...
Recent satellite imagery shows a well-defined shortwave trough
moving through the Upper Midwest towards the Upper Great Lakes.
Surface analysis places the low associated with this shortwave over
the northern MN/WI border vicinity, with an attendant cold front
extending back southwestward through northwest IA,
southeast/south-central NE, and far northwest KS. A modest
pre-frontal trough is in place just ahead of this cold front. The
shortwave trough is forecast to continue eastward, while the cold
front progresses eastward/southeastward. Northern portion of this
front (closer to the surface low and parent shortwave) will make
notably more eastward/southeastward progress than the
southern/western portion, which will move more gradually
southeastward.
Low-level moisture advection is anticipated ahead of the front, but
with mid 50s dewpoints currently in central OK, the extent and
quality of this moisture will likely be somewhat limited. Filtered
heating and mixing could also reduce dewpoints. Even so, dewpoints
will likely still reach at least the mid 40s across southern WI,
gradually increasing into the mid 50s across southeast KS/southwest
MO/northeast OK. This is expected to be enough moisture to support a
narrow corridor of modest buoyancy. Strongest ascent will be near
the surface low and shortwave trough across the Upper/Mid MS Valley,
supporting higher storm coverage than areas farther southwest. A few
high-based storms capable of wind damage and isolated hail are
possible.
Farther southwest, lower storm coverage is expected, particularly
from west-central IL into southeast KS. Thunderstorm chances across
much of this area appear low enough to remove severe probabilities.
The only exception is over the southeast KS/southwest MO vicinity.
Here, greater low to mid-level moisture could still support a storm
or two. Shear is strong enough to support hail with any storms that
mature.
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