105 

ACUS02 KWNS 290608

SWODY2

SPC AC 290606



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



$$