ACUS02 KWNS 070610
SWODY2
SPC AC 070609

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0109 AM CDT Thu Aug 07 2025

Valid 081200Z - 091200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms are expected Friday afternoon and
evening across parts of the northern Plains and upper Mississippi Valley.

...Northern Plains/Upper Mississippi Valley...
A negatively tilted mid-level trough and an associated 50 to 60 knot
jet streak will move through the northern Plains on Friday. At the
surface, a cold front will advance eastward across the Dakotas, as
convection early in the day moves through the upper Mississippi
Valley. Ahead of the front, a moist and strongly unstable airmass
will be in place, with surface dewpoints from the upper 60s to the
mid 70s F. Low-level convergence will increase ahead of the front in
the afternoon, helping to support scattered thunderstorm
development. A cluster of strong to severe storms appears likely
across parts of the northern Plains Friday afternoon and evening.

A pristine thermodynamic environment is forecast to develop across
the northern Plains Friday afternoon. NAM forecast soundings in the
late afternoon along the instability axis near Fargo, North Dakota
have MLCAPE near 5,500 J/kg with 700-500 mb lapse rates approaching
8.5 C/km. Along the axis of instability, 0-6 km shear is forecast to
be in the 35 to 45 knot range, which should be favorable for
supercells with large hail. Hailstones of greater than 2 inches in
diameter will be possible within the stronger cores. Severe wind
gusts will also be possible.

There is some concern that convection along or ahead of the front
will remain to the west of the strongest instability. Although the
models vary concerning this scenario, the latest ECMWF has trended
toward an earlier convective initiation. The ECMWF solution, which
also develops convection further to the south, would be more
favorable for a significant severe weather event across the northern
Plains Friday afternoon and evening.

...Western Dakotas...
A post-frontal airmass will be in place across the western Dakotas
on Friday, as a cold front advances eastward away from the region.
Warming surface temperatures will contribute to weak instability by
afternoon, with MLCAPE approaching 1000 J/kg in some areas.
Large-scale ascent associated with a mid-level shortwave trough
should aid the development of a few thunderstorms during the late
afternoon and early evening. Moderate deep-layer shear and steep
mid-level lapse rates could be enough for a localized severe threat,
with hail and isolated severe wind gusts possible.

..Broyles.. 08/07/2025

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