Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Jul 25 2026

Valid 251300Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MONTANA AND
SOUTH DAKOTA...

...SUMMARY...
Storms with scattered severe wind gusts are possible across parts of
Montana and South Dakota this afternoon and evening.

...Montana to Dakotas...
A prominent upper ridge will persist over much of the
Southwest/central CONUS through tonight, with very hot temperatures
expected this afternoon from Montana into the Dakotas. Isolated to
scattered storms within the hot and well-mixed environment will
result in a broad area of at least isolated severe-wind potential.

For parts of western/central Montana, convection that develops by
early/mid afternoon near the high terrain is expected to spread
eastward. This convection may be aided by a low-amplitude mid-level
vort max moving around the periphery of the upper ridge. Increasing
storm coverage and gradually strengthening mid/upper-level flow may
allow for one or more outflow-driven clusters to develop and spread
east-northeastward into early evening, with a threat of severe wind
gusts. Localized gusts of 75+ mph cannot be ruled out, especially if
deeper convection is able to spread into areas where very deep
mixing and heating to near/above 100 F occurs prior to storm
arrival. 

Farther east, very strong heating is expected across parts of
western/central South Dakota, with temperatures in some areas
potentially rising to near/above 105 F. Low-level moisture will be
relatively sparse, but MLCAPE of near/above 1000 J/kg will be
possible where 50s F dewpoints can be maintained within the
well-mixed environment. Initial storm development near the Black
Hills will quickly become outflow dominant as it spreads eastward,
with an increasing threat of severe gusts as storms tend to increase
and potentially modestly organize as outflows aggregate. Some
guidance depicts development of a persistent cluster or loosely
organized MCS that moves eastward across South Dakota along a weak
surface boundary. Should this occur, a corridor of more organized
severe-wind threat (with gusts potentially near/above 75 mph) will
be possible this evening.

...Upper Midwest/Upper Great Lakes...
Conditional severe potential exists across parts of the Upper
Midwest spanning Minnesota to Upper Michigan, although confidence
regarding storm coverage and timing remains very low within the
weakly forced environment characterized by generally rising upper
heights. As morning stratus thins/erodes, moderate to strong
destabilization is possible along/south of a surface front
that is forecast to extend from northeast North Dakota into northern
Minnesota/Wisconsin by late afternoon.

Impressively long hodographs with effective shear of 50+ kt will be
more than sufficient for storm organization, but most guidance
remains rather muted regarding potential for diurnal storm
development. If storms are able to develop during the afternoon or
evening, then a threat for hail, damaging wind, and possibly a
tornado could evolve. Even if diurnal storm development is limited,
at least isolated vigorous elevated storms may evolve within a
warm-advection regime near/north of the front late tonight, which
would pose a threat for hail and perhaps locally damaging wind.

...Northeast Nevada/northern Utah/eastern Idaho...
Storm development is expected during the afternoon across parts of
northeast Nevada, along the western periphery of the upper ridge.
These storms will spread into adjacent parts of southeast Idaho and
northwest Utah with time. Strong to locally severe wind gusts will
be possible with these storms as they move northeastward within a
well-mixed environment.  

...South-central/southeast Arizona...
High-based convection is again expected across southeast Arizona
during the afternoon, with initial downburst potential. A modest
enhancement to easterly flow along the southern periphery of the
upper ridge may allow for localized strong to severe wind gusts to
spread westward into parts of south-central Arizona, before
convection weakens tonight.

..Guyer/Wendt.. 07/25/2026

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0345 AM CDT Sat Jul 25 2026

Valid 281200Z - 021200Z

...DISCUSSION...
...Day 4/Tuesday...
An upper low is forecast to develop from southwest ON into the
northern Mid-Atlantic with an attending belt of 35-45 kt mid-level
flow extending from the OH Valley into the southern Mid-Atlantic. 
At the surface, a cyclone will remain vertically aligned with the
upper low, while a trailing cold front advances through the upper OH
and TN Valleys into the Mid-Atlantic, Carolinas, and Gulf Coast
states. A lee trough is expected to develop ahead of the cold front
along the Piedmont Tuesday afternoon.
 
Showers and thunderstorms (some potentially strong) are expected to
be ongoing Tuesday morning from the upper OH Valley into the
Mid-Atlantic, aided by forcing for ascent ahead of the upper low and
low-level warm air and moisture advection along a 30-40 kt low-level
jet. That activity is expected to linger into the afternoon from NY
and PA into western New England, which will limit the potential for
air mass destabilization in those areas. Stronger daytime heating
appears possible south of the Mason-Dixon Line, where moderate
instability is forecast across the pre-frontal warm sector. 

Thunderstorms are expected to increase in coverage and intensity
during the afternoon along the cold front and lee trough from the
Delmarva into central Appalachians and VA/NC Piedmont. The moderate
instability combined with 35-40 kt of deep-layer shear will support
organized storm modes with the primary hazard being damaging wind
gusts.

Other more isolated severe storms appear possible over the central
High Plains within a low-level upslope regime.  

  
...Day 5/Wednesday...
The Day 4/Tuesday upper low is forecast to slowly drift northeast
with a belt of stronger mid-level winds overspreading New England. A
surface low will remain vertically aligned with the mid-level system
with convergence in the vicinity of that feature and a trailing
front serving as the focus for afternoon thunderstorm development.
The models suggest that southern to central parts of New England may
become moderately unstable, which, combined with the slight shear
enhancement, may support a few strong to severe storms.

Additional strong to severe storms appear possible along a frontal
zone in the Southeast, where a very moist air mass will contribute
to moderate to strong instability.

Uncertainty in the extent of the severe weather threat in both areas
precludes the delineation of a 15% probability contour.  


...Days 6-8/Thursday through Saturday...

The 00Z ensemble means are in reasonably good agreement in depicting
the retrogression of the upper high from the Southern Rockies into
the lower CO Valley. A concurrent weakening and broadening of the
eastern CONUS trough is also forecast. There is a model signal for a
stronger mid-level system to move into BC and the Pacific Northwest
by Day 8/Saturday. Deterministic guidance indicates a series of weak
disturbances tracking from the northern Plains to along and east of
the MS Valley during this time period with sporadic occurrences of
severe weather possible. However, the large-scale pattern currently
appears unsupportive of an organized severe weather episode.