101
ACUS48 KWNS 250829
SWOD48
SPC AC 250827

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CDT Tue Aug 25 2026

Valid 281200Z - 021200Z

...DISCUSSION...
Severe weather is possible across the northern Plains into the Upper
Midwest starting Day 4/Friday and continuing through the weekend.
The specific evolution remains unclear with quite a range of
ensemble solutions at this time. Nonetheless, expect severe weather
somewhere within this broad region each day.

...Day4/Friday...
As the upper-level ridge flattens on Friday, lee troughing will
develop across the northern High Plains. Moderate to strong
instability is forecast to develop across the western Dakotas ahead
of this lee trough. Any weak mid-level shortwave trough to provide a
focus for this threat remains nebulous. Therefore, the location of
any surface features remains unclear and thus, it is difficult to
highlight a more specific region with a greater severe weather
probability at this time.

...Day5/Saturday...
Severe weather may be possible across portions of the Upper Midwest
on Saturday, but this threat will be somewhat dependent on the
location and intensity of Day 4 convection.

...Day6/Sunday...
The ECMWF and AI-ECMWF remain relatively consistent showing a trough
traversing the northwest on Saturday and emerging across the
northern Plains on Sunday. Meanwhile, the GFS and AI-GFS have
trended more progressive, and the individual GEFS members show
substantial spread in the upper-level pattern for Sunday/Day6. The
relative consistency in timing and location of the upper-level
trough from the ECMWF build confidence for this solution. However,
even the ECMWF and AI-ECMWF trended slightly less amplified with
this trough. Therefore, the combination of large spread in the upper
pattern from GEFS members and a slightly deamplified trend from the
ECMWF provide enough uncertainty to avoid adding probabilities at
this time.

..Bentley.. 08/25/2026