Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0106 AM CDT Mon Jun 29 2026
Valid 301200Z - 011200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHERN WISCONSIN
INTO THE UPPER PENINSULA OF MICHIGAN...
...SUMMARY...
Severe thunderstorms will be possible from parts of the central High
Plains into the Upper Midwest, and across parts of the Northeast on
Tuesday.
...Synopsis...
An upper low will be present in the Canadian Prairies with a belt of
stronger mid-level flow extending into the Upper Midwest. The
amplified upper ridge in the Midwest/East will be somewhat
suppressed as a result. A stalled surface boundary will be present
from the central High Plains into the Upper Midwest. Moderate to
strong mid-level northwesterlies will be present across the
Northeast with possible MCVs/shortwaves moving into the region.
...Mid-Missouri Valley into Upper Midwest...
Convection that occurs in Minnesota overnight Monday into early
Tuesday is expected to weaken as it moves eastward. Given the
weakening and veering low-level jet, it does not appear this
activity will have much of an impact on the environment in northern
Wisconsin into the Upper Peninsula of Michigan. A stalled surface
boundary will be located from northern Nebraska into Minnesota and
northwest Wisconsin. Very rich moisture (mid/upper 70s F dewpoints)
will exist in the warm sector. With mid-level lapse rates of 7.5-8
C/km, strong to extreme buoyancy will develop by the afternoon. With
the main upper low in the Canadian Prairie, large-scale ascent will
be subtle/nebulous. That said, convective temperatures should be
reached at least locally with additional lift expected from lake
breeze boundaries. Most models, including both global/regional
models and CAMs, suggest development is probable from parts of
northern Wisconsin into the Upper Peninsula. Effective shear of
40-50 kt will promote some storm organization. However, magnitude of
buoyancy along with modest low-level flow will likely result in
storms becoming outflow dominant. A targeted Slight Risk has been
added for this potential. Damaging winds are the most likely hazard
with this activity, but isolated large hail could also occur.
Farther southwest into southern Minnesota/Iowa/Nebraska/South
Dakota, storm coverage is much less certain. There could be an
increase in thunderstorm activity as the low-level jet increases
during the evening. Should this occur, damaging winds and perhaps
isolated large hail would be possible. Shear will be weaker in these
areas and the severe threat will likely remain marginal/isolated.
...Northeast...
Questions remain as to the timing of MCV/convection moving out of
Canada. Given the potential for early precipitation to occur and
limit surface-based instability, the Marginal Risk has been
maintained for this outlook. Nevertheless, the environment will be
favorable for strong to severe storms. Effective shear is expected
to be around 50 kt. Damaging winds and large hail are likely the
main risks; however, if storm mode is more cellular, a greater
tornado risk could also be present. Trends in guidance will need to
be monitored.
...Colorado/Kansas/southwest Nebraska...
A modest lee trough will promote moisture advection into the central
High Plains. A subtle shortwave trough moving through the central
Rockies may aid in storm development. The timing of storm
development is not certain, but most guidance would suggest this
occurs at or after 00Z. Steep mid-level lapse rates and moderate
deep-layer shear will promote organized storms that will be capable
of large hail (isolated to around 2 in.) and severe winds. Low-level
shear will be enhanced near the surface trough/low, but concerns
over low-level thermodynamics limit confidence in a tornado threat.
..Wendt.. 06/29/2026
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