RSS Mesoscale Discussions from Storm Prediction Center
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0241 PM CDT Fri Aug 08 2025
Valid 082000Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
TONIGHT FOR PARTS OF THE UPPER MIDWEST AND THE CENTRAL HIGH
PLAINS...
...SUMMARY...
Scattered severe thunderstorms with damaging winds, large hail, and
a couple tornadoes are possible this evening and tonight across
parts of the Upper Midwest and the central High Plains.
...20z Update...
...Upper Midwest...
Latest radar/satellite trends show a residual storm complex and
cloud cover over northeast Minnesota. This activity continues to
diminish, with some weak convection developing in proximity. Surface
observations suggest little evidence of extensive outflow in its
wake, though southeasterly surface winds are prevalent across much
of Minnesota where cloud cover has remained persistent. To the west,
a cold front continues to advance eastward and is beginning to
impinge upon portions of northwest Minnesota into eastern South
Dakota.
Storm initiation is still expected by early evening along the cold
front in eastern South/North Dakota, with a quick transition from
cellular to linear modes. Not much has changed in terms of
expectations from the prior outlook. As this activity grows upscale
and matures, some potential for a more concentrated corridor of
damaging winds may emerge in far northeast Minnesota, but details
remain uncertain and will be reevaluated in the 01z Outlook. With
that said, given the potential for upscale growth, have expanded the
Marginal area (Level 1 of 5) eastward into portions of northeast
Iowa and vicinity.
...Southwest South Dakota/Nebraska Panhandle...
Surface observations and SPC mesoanalysis show a post-frontal
airmass with enough residual moisture to allow for modest
destabilization across the region. Recent CAM guidance suggests the
potential for isolated convection to develop in the high terrain of
eastern Wyoming and persist eastward into southwest South Dakota and
the Nebraska Panhandle. Given effective shear of 45-50 kt in
association with enhanced flow along the southern periphery of the
upper-level trough, a few supercell storms are possible with severe
hail/wind the main threats. Therefore, have introduced a Slight Risk
(Level 2 of 5) to encompass this potential.
..Karstens/Lyons.. 08/08/2025
.PREV DISCUSSION... /ISSUED 1118 AM CDT Fri Aug 08 2025/
...Upper Midwest...
The large convective complex that affected ND/MN last night has
mostly dissipated, with the associated shortwave trough lifting
across the MN Arrowhead. Shortwave ridging is occurring in the wake
of this system, which should suppress deep convective development
for most of the afternoon. Southeasterly low-level winds and
daytime heating across much of MN and eastern SD will help
re-establish a very moist/unstable air mass (MLCAPE > 4000 J/kg) by
late afternoon.
Another strong shortwave trough now over WY will begin affecting the
ND/MN area by that time, with an associated cold front approaching
the area. Scattered thunderstorms are expected to form along/ahead
of the front, mainly after 00z. Deep-layer shear will support
supercell storm structures capable of large hail and damaging wind
gusts. A few tornadoes are also possible, given the very moist
environment and backed low-level winds. However, many of the storms
may be elevated and behind the front. Activity will persist deep
into the night, spreading eastward across MN and into parts of
northern WI and western Upper MI.
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