RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Tue Jul 07 2026
Valid 071300Z - 081200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN
HIGH PLAINS INTO THE UPPER MIDWEST...
...SUMMARY...
Widely scattered to scattered severe storms capable of large hail
and severe wind gusts are possible from the northern High Plains
into parts of the Upper Midwest today into tonight. Isolated severe
storms capable of mainly damaging wind gusts are possible this
afternoon and evening from the southern Mid-Atlantic into the
Carolinas, the Sabine River Valley, parts of the Great Basin, and
southeast Arizona.
...Northern High Plains into the Upper Midwest..
A large area of showers and thunderstorms is currently moving
northeastward across eastern MT and western ND. This activity, which
appears to be associated with a weak lead shortwave trough, is
forecast to continue northeastward/eastward throughout the day.
Storm severity will be limited by a lack of buoyancy and stronger
ascent. However, cloud cover associated with this activity will aid
in sharpening a warm front that is expected to develop as the cold
front, which moved across SD last night, returns northward amid
low-level moisture advection ahead of a stronger shortwave trough.
Thunderstorms are first expected to develop back farther west across
the northern High Plains, where moist easterly upslope flow combined
with steep mid-level lapse will foster airmass destabilization.
Moderate to strong buoyancy (i.e. MLCAPE 1000 to 2000 J/kg) and
moderate deep-layer shear (i.e. effective bulk shear of 40 to 50 kt)
will support the potential for a few supercells capable of large
hail and damaging gusts. One or more bowing segments could evolve
from these supercells, with at least some potential for stronger,
more organized line capable of gust over 70 mph to move across SD.
However, confidence in a corridor of greater severe potential is
currently limited, owing to the likelihood of complex interactions
between outflows and new storm development over the MT/WY/SD border
intersection vicinity.
Thunderstorm development also appears probable farther east along
the warm front during the evening as the low-level jet increases.
Large to very large hail is possible with this activity initially,
before upscale growth results in bowing clusters.
Additional storms are possible near the lee trough from southeast WY
into northeast CO and the NE Panhandle during the afternoon into
evening. The local environment will feature a deep and well-mixed
boundary layer, which will support the potential for a few severe
wind gusts and perhaps some hail.
...Great Basin...
A modest shortwave trough is forecast to move through northeast NV
and northern UT this afternoon and evening. Modest mid-level
moisture and lift associated with this wave will support isolated to
widely scatted thunderstorms atop a deep and well-mixed boundary
layer. Modest updrafts and high cloud bases atop very steep
low-level lapse rates will support locally severe wind gusts with
the strongest storms.
...Southern AZ...
Increased mid-level moisture will support thunderstorm development
across the higher terrain of eastern AZ during the afternoon. Modest
easterly mid-level flow is expected over the region, with some
potential for the thunderstorms to progress westward into the lower
elevations during the late afternoon. A few strong gusts are
possible.
...East Texas into the Sabine River Valley...
Early-morning satellite imagery shows a broad upper low centered
over the Mid-South, with a weak vorticity maximum pivoting through
its southwest periphery over southern AR/northern LA. A few
thunderstorms are ongoing in the vicinity of this vorticity maximum,
with a gradual increase in thunderstorm coverage later this morning
through the afternoon as ascent from this vorticity maximum
interacts with the moist and unstable airmass in place. Vertical
shear is weak but some loosely organized cold pools may evolve,
supporting the potential for sporadic damaging wind gusts.
...Southern Mid-Atlantic into the Carolinas...
A moist and moderately unstable air mass is expected to support
scattered thunderstorm development across the region, beginning over
the Blue Ridge Mountains during the early afternoon and expanding
southward along the weak lee troughing into the central Carolinas.
Some sea breeze development is possible from the VA Tidewater along
the coastal Carolinas as well. Vertical shear will remain weak,
limiting the potential for storm organization. Even so, the presence
of steep low-level lapse rates will enhance downdraft potential,
leading to the risk for sporadic damaging wind occurrences,
especially with any storm clusters.
..Mosier/Thornton.. 07/07/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0406 AM CDT Tue Jul 07 2026
Valid 101200Z - 151200Z
CORRECTED FOR SPELLING
...DISCUSSION...
Medium-range model output continues to indicate the evolution of an
increasingly prominent mid/upper high across the lower Colorado
Valley and Plateau late this week into next weekend. It appears
likely that this will continue expanding and encompassing a
significant portion of the interior U.S. by early next week, as an
evolving larger-scale trough begins to dig across and southeast of
Hudson Bay. While there appears relatively small spread within and
among the various model output concerning this larger-scale
evolution, there is considerable spread concerning the migration of
one particularly notable short wave trough around the periphery of
the ridge.
Of particular concern, it appears probable that a plume of very warm
elevated mixed-layer air will advect along the southern fringe of a
belt of intensifying flow around the northern through northeastern
periphery of the mid/upper ridge. As it does, coupled with
low-level moistening, this type of regime could support the periodic
evolution of organizing clusters, potentially including one or two
potentially long-lived, accompanied by swaths of damaging surface
gusts.
It appears that this could focus anywhere from near and north of the
central Canadian/U.S. border vicinity through the Great Lakes into
the Northeast by early next week. However, due to lingering
uncertainty with the synoptic developments, and the generally low
predictability of these mesoscale systems, in this type of regime at
this extended range, severe probabilities still appear less than 15
percent. However, depending on model trends, this could change in
later outlooks for this period.
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