Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Thu Jun 11 2026
Valid 111630Z - 121200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN ILLINOIS...FAR EASTERN IOWA...AND FAR SOUTHERN WISCONSIN...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC AND CENTRAL APPALACHIANS...
...SUMMARY...
Widespread severe thunderstorms are expected this afternoon and
evening across parts of the Midwest and Great Lakes region,
including far eastern Iowa, northern Missouri, northern/central
Illinois, southern Wisconsin, Lower Michigan, and northern Indiana.
This includes the potential for widespread/intense damaging winds
(some 75+ mph), large hail, and several tornadoes, some of which may
be strong to intense.
...Midwest/Great Lakes...
An active and impactful severe weather event is still expected
across parts of the Midwest Great Lakes later this afternoon and
evening. Ongoing bowing cluster across southeast IA/northwest
IL/southwest WI and vicinity may continue to pose at least some
severe wind and embedded QLCS tornado threat as it continues
east-northeastward across parts of the Midwest this afternoon. There
is still airmass recovery underway ahead of this activity,
especially into central/northern IL, northern IN, and parts of
southern Lower MI where strong heating is occurring. Enhanced
mid-level west-southwesterly winds associated with a potent
shortwave trough over the northern Plains/Upper Midwest will
overspread the developing warm sector this afternoon, and support
organized severe potential, including the possibility of multiple
tornadic supercells and widespread severe/damaging winds.
Even so, greater than usual uncertainty exists regarding
redevelopment later today on the southern/western flank of ongoing
convection across northern IL into northeast MO and vicinity. A
gradual increase in both low-level and deep-layer shear is
anticipated across this area as a 30-40+ kt southerly low-level jet
develops eastward in tandem with the eastward-ejecting shortwave
trough and mid-level jet. A mix of supercells and bowing segments
appears probable as renewed thunderstorms develop along/ahead of the
surface cold front this afternoon in a strongly unstable and rather
favorably sheared environment. If at least semi-discrete supercell
structures can be maintained, then potential exists for several
tornadoes, and multiple strong to intense tornadoes (EF-2/3+) given
the enhanced low-level shear. Isolated large to very large hail may
also occur with any sustained supercells.
Otherwise, numerous to potentially widespread severe/damaging winds
also appear likely through the period across parts of
northern/central IL into southern Lower MI and northern IN. Both the
ongoing cluster and eventual upscale growth of convection that
develops this afternoon will likely produce severe/damaging winds,
some of which could be significant (75+ mph). The northern extent of
the severe risk into WI and northern Lower MI remains uncertain, but
at least some wind and/or tornado threat will likely continue with
eastward extent into the southern Great Lakes and northern IN this
evening.
...Eastern Kansas/Southern Missouri into the Southern Plains...
Additional thunderstorms will likely develop this afternoon and
evening along the trailing cold front into portions of eastern
KS/southern MO into the southern Plains. Stronger deep-layer shear
is forecast to lag behind/to the north of the cold front. Still,
around 20-30 kt of effective bulk shear and moderate to strong
instability will support marginal supercell structures and loosely
organized multicells capable of producing both large hail and
damaging winds. A large component of boundary-parallel shear will
likely lead to clustering and messy convective modes through the
evening before thunderstorms gradually weaken with the loss of
daytime heating.
...Mid-Atlantic/Central Appalachians...
Recent visible satellite imagery across much of the Mid-Atlantic and
central Appalachians shows mostly sunny to partly cloudy conditions,
with ample low-level moisture present per latest surface
observations and area 12Z observed soundings. Large-scale ascent
associated with multiple low-amplitude mid-level shortwave troughs
will likely support the development of widely scattered
thunderstorms by afternoon across parts of the Mid-Atlantic into the
central Appalachians. Though deep-layer shear is forecast to remain
modest, moderate to strong instability will exist with continued
diurnal heating this afternoon. This will support stronger updrafts
capable of scattered severe/damaging winds and perhaps isolated
hail. Multiple clusters should eventually emerge, with potential for
organizing along outflow/cold pools, and more focused corridors of
damaging winds possible across parts of the I-95 corridor from
northern VA to eastern PA and NJ.
..Gleason/Flournoy.. 06/11/2026
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