307 
ACUS03 KWNS 150728
SWODY3
SPC AC 150727

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0227 AM CDT Mon Jun 15 2026

Valid 171200Z - 181200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID-MISSISSIPPI VALLEY INTO INDIANA...

...SUMMARY...
An all-hazards severe thunderstorm episode is expected across
portions of the Middle Mississippi Valley into Indiana on Wednesday.
Intense thunderstorms may produce swaths of damaging wind, as well
as strong tornadoes and large hail.

...Midwest...

A midlevel shortwave trough is forecast to move from the northern
Plains through the Upper Midwest and Great Lakes region on
Wednesday. As this occurs, very strong deep-layer flow, especially
for this time of year, will move across portions of the Mid-MS
Valley into the Ohio Valley. A westerly 500 mb jet streak
characterized by at least 70-80 kt will overspread parts of
IA/MO/IL/IN in the afternoon and evening. Meanwhile, a 50+ kt
southwesterly 850 mb low-level jet will spread across the same area
during the afternoon/evening, just ahead of an
east/southeast-advancing surface cold front. These strong wind
fields, in conjunction with a surface low moving eastward across MN
and the Upper Great Lakes, will aid in northward transport of rich
boundary layer moisture (upper 60s to near 70 F surface dewpoints).
Cooling aloft will steepen midlevel lapse rates, and moderate to
strong destabilization is expected across the warm sector. Overall,
this pattern should support numerous severe storms. While convective
evolution remains uncertain, it is likely that at least some initial
supercell risk will unfold during the afternoon and early evening
(particularly across MO/IL), with potential for one or more bowing
MCSs developing with time. This environment will support a risk for
all severe hazards, and particularly swaths of damaging winds, and
strong tornadoes.

Some uncertainty remains regarding the northward extent of the
severe risk. Most medium range guidance indicates a lead shortwave
impulse may move across IA/IL early in the day. Coupled with strong
warm advection across the region, morning thunderstorm develop
near/north of a warm front oriented from southeast MN into northeast
IL at midday could suppress northward development of the warm front.
Likewise, the southwest extent of the risk area into portions of
KS/OK may be limited by capping concerns, and weaker forcing for
ascent. Meanwhile, the southward extent of the severe risk across
the Ohio Valley will be modulated by the stronger westerly component
of mid/upper flow overnight and slow southward movement of the
surface cold front. The risk area may shift some in coming days as
surface boundaries and other mesoscale details become better
resolved.

..Leitman.. 06/15/2026

$$


File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS03/20260615T0728.txt



572 
ACUS03 KWNS 141928
SWODY3
SPC AC 141927

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0227 PM CDT Sun Jun 14 2026

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MIDWEST INTO LOWER MICHIGAN...

...SUMMARY...
Isolated strong to severe thunderstorms are possible Tuesday
afternoon and evening across parts of the Midwest into Lower
Michigan.

... Synopsis ...

Broad mid-level troughing across the eastern US will persist on
Tuesday. A short-wave trough will move across the Great Lakes as it
moves through the basal region of the eastern US long-wave trough.
Late in the forecast period, a second short-wave trough will dig
southeast into the northern Plains.

At the surface, one front will be draped across the northern Gulf
Coast states, suppressing the richest boundary layer moisture to the
south. A second front will quickly move from the Upper Midwest
across the Ohio Valley into the Lower Great Lakes by Wednesday
morning as a surface low slowly pivots across the Lake Superior. 

Overnight Tuesday, cyclogenesis will occur across the northern
Plains in response to the approaching short-wave trough. A deepening
surface low will induce more substantial northward moisture
advection from the southern into central Plains.


... Midwest into Lower Michigan ...

Low-level moisture return will be tempered on Tuesday, owing to the
stalled front across the northern Gulf Coast states and only modest
low-level mass response to the approaching mid-level short-wave
trough. That said, modest southwesterly moisture advection ahead of
the cold front should support a narrow corridor of surface dewpoints
rising into the upper-50Fs to low-60Fs. At the same time, mid-level
lapse rates should steepen with the approaching trough, resulting in
MUCAPE between 500-1500 J/kg, conditioned on the quality of the
moisture return. Storms, perhaps multiple rounds, should develop
along or ahead of the advancing front. Gusty winds and hail should
be the main hazards, with storms generally weakening with eastward
extent due to the loss of diurnal heating and weaker moisture
return.

..Marsh.. 06/14/2026

$$


File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS03/20260614T1928.txt