685
ACUS02 KWNS 091722
SWODY2
SPC AC 091721

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1221 PM CDT Tue Jun 09 2026

Valid 101200Z - 111200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
MINNESOTA...WISCONSIN...NORTHERN ILLINOIS...AND EASTERN IOWA...

...SUMMARY...
Scattered to numerous severe thunderstorms capable of large hail in
excess of two inches in diameter, a few strong tornadoes, and
damaging winds with gusts in excess of 75 mph appear likely across
portions of the Upper Mississippi Valley and Midwest Wednesday
afternoon into night.

...Synopsis...

An upper trough will pivot northeast across the Upper Midwest on
Wednesday. Enhanced deep-layer southwesterly flow associated with
this system will overspread the Upper MS Valley vicinity in tandem
with an intensifying low-level jet during the late afternoon into
the nighttime hours, providing ample support for organized
convection.

At the surface, a quasi-warm front/moisture gradient is noted from
north-central MN into northern Lower MI in model guidance during the
morning. This boundary may lift northward through the day, though
some influence from the Great Lakes may maintain this gradient
across northern WI/MI. Otherwise the surface cold front will be
located from northwest MN into northwest KS by midday. This boundary
will march eastward through the period, becoming oriented from Upper
MI/central WI to southeast NE by Thursday morning. The southern
extent of the front will stall over KS as a surface low deepens
across the central Plains overnight in response to another upper
shortwave trough ejecting over the Rockies/High Plains.

...Upper Midwest/Great Lakes vicinity into northeast KS...

A somewhat complex scenario is evident for Wednesday, with potential
for more than one round of severe storms possible for parts of the
region, particularly IA/WI/IL. This complex scenario will be
influence by potential remnant MCVs and outflows from Day 2/Tuesday
convection persisting into Wednesday morning or migrating into the
area by early afternoon ahead of the main synoptic front. Additional
convection will then also be possible along the main front late
afternoon into the nighttime hours.

Rich boundary layer moisture will be in place across the region,
with surface dewpoints in the upper 60s to low 70s F common. Steep
lapse rates atop this very moist boundary layer will support
moderate to strong instability from 2000-4000 J/kg. Initial storm
development will be supercells given favorable vertically veering
shear profiles with 35+ kt effective shear magnitudes over a large
area. With time, one or more bowing clusters may develop via cold
pool consolidation and linear organization along the cold front as a
40+ kt low-level jet develops by early evening. Initial large to
very large hail and a strong tornado risk will accompany discrete
cells. Damaging wind potential will be greater with more linear
storm mode and some gusts could be greater than 75 mph with these
organized linear modes.

During the early evening, additional convection is expected to
develop along the surface boundary from northeast KS into northwest
MO and southern IA. Some forecast guidance (particularly the RAP)
suggests this zone may be particularly favorable for supercell
development as the low-level jet increases. Large to very large
hail, damaging gusts a possibly a strong tornado will be possible
with this convection along the southwest extent of the surface
front.  Overnight, additional storms may develop across eastern NE
into western IA in a warm advection regime ahead of the upper trough
ejecting into the central High Plains after 06z. This activity will
likely be elevated, but would still pose a risk for large hail and
perhaps strong wind gusts.

...South-central KS into western OK and the TX Panhandle...

Vertical shear will become more limited with southwest extent on
Wednesday. Capping also may limit storm development/coverage into
the TX Panhandle. Nevertheless, any storms that do development will
likely be somewhat higher-based and pose a risk for strong outflow
winds. Large to very large hail will also be possible with any
longer-lived storms given steep midlevel lapse rates, strong
instability and elongated/straight forecast hodographs.

...Lower Great Lakes and Mid-Atlantic...

A weak midlevel shortwave trough will migrate across the region on
Wednesday. This will result in modestly enhanced vertical shear as
midlevel flow increases during peak heating. At the surface, rich
boundary layer moisture will overspread the area. Dewpoints in the
mid to upper 60s F and strong heating into the 80s F will result in
moderate destabilization. Morning convection may be ongoing across
portions of the Delmarva vicinity, resulting in uncertainty with
regards to the extent of afternoon severe potential, but at least
isolated potential for strong gusts is possible from NY/PA/NJ
southward into the Delmarva.

..Leitman.. 06/09/2026

$$