Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0224 AM CDT Tue Sep 08 2026

Valid 111200Z - 161200Z

...DISCUSSION...
...Days 4-5/Fri-Sat -- Plains to the Great Lakes vicinity...

Severe potential could develop across portions of the Plains into
the Upper Midwest on Day 4/Friday as boundary layer moisture spreads
northward ahead of a southeastward-advancing cold front. Moderate to
strong destabilization ahead of the front, and enhanced vertical
shear courtesy of a modest upper shortwave trough moving across the
northern Plains/Upper Midwest vicinity, should be sufficient for
organized convection mainly from Friday evening into early Saturday.

Some severe potential could persist into Day 5 Saturday as the
surface front stalls over the central/southern Plains vicinity but
continues eastward across the upper Great Lakes region. A moist
boundary layer will be in place, but stronger flow aloft will become
increasing displaced to the north of stronger instability,
precluding 15 percent delineation at this time. 

...Days 6-8/Sun-Tue...

An upper trough over the northwestern U.S. will develop eastward
across the Plains and Great Lakes early next week. Another cold
front will move across the area, and some severe potential could
again sweep across the Plains to the Upper Midwest/Great Lakes
vicinity. Medium range forecast guidance generally maintains
stronger instability offset from enhanced flow aloft, partly due to
the early cold frontal passage in the Day 4-5/Friday-Saturday time
frame and strong surface high pressure over the Great Lakes in the
wake of that frontal passage. Trends will be monitored and
probabilities could become necessary in later outlooks.