RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1142 AM CDT Sat Jun 27 2026
Valid 271630Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
TENNESSEE VALLEY TO CAROLINAS...
...SUMMARY...
Severe thunderstorms are likely today across the northern High
Plains including northeast Wyoming and eastern Montana into the
western Dakotas, with storms capable of very large hail, very strong
outflow winds (80+ mph), and tornadoes late this afternoon into
tonight.
...Northern High Plains this afternoon into tonight...
A rather active severe-weather scenario is anticipated regionally
later today, including the potential for intense/locally significant
severe storms. A lead shortwave trough/speed max will continue to
approach through late today, with the exit region of a strong
upper-level jet overspreading the region including 50+ kt
southwesterlies above 5km AGL. Boundary-layer dewpoints in the 60s F
will continue to spread northward regionally, to the east of a
deepening surface low across northeast Wyoming toward the far
western Dakotas, and a sharpening lee trough/dryline across a more
prevalent north/south extent of the High Plains. This low-level
moistening will occur beneath a plume of steep mid-level lapse rates
emanating from the Great Basin and north-central Rockies.
Initial surface-based development is expected near the surface
low/trough near the Big Horn Mountains toward the
Wyoming/Montana/North Dakota border vicinity. The maturing stronger
initial storms will almost certainly be supercellular owing to
moderate to large CAPE and a strong wind field. The risk for large
to very large hail (2-3 inches in diameter) is greatest near this
aforementioned border region where supercells are forecast early in
the convective life cycle, although additional/somewhat more
discrete development will also likely occur a bit later farther
southeastward across northwest South Dakota.
A few tornadoes are also possible particularly in the more
moisture-rich environment near the surface triple point, but
relatively large temperature-dewpoint spreads and a transition to
upscale growth may temper the tornado threat, particularly with
northward extent either side of the Montana/North Dakota border
vicinity. As more storms develop leading to storm mergers and
coalescing outflow, a linear cluster will likely develop into a
maturing/accelerating bow echo into western North Dakota this
evening, with significant/intense thunderstorm winds (80+ mph)
possible.
Severe storms will likely develop eastward tonight across the
Dakotas, and prior to that, diurnally enhanced, but more isolated
intense, development is plausible as far south as western Nebraska
with large hail and damaging winds.
...Northern Intermountain West including northern UT/western WY...
Influenced by a lead shortwave trough/speed max associated with the
prominent upper-level trough centered over the Pacific Northwest,
strong to locally severe thunderstorm potential will probably exist
early today. The prolifically strong wind field and modest
destabilization will tend to focus today across northern Utah,
southeast Idaho into western Wyoming, including the Star Valley
vicinity. Severe-caliber wind gusts and some hail may occur.
...Mid-South/Tennessee/southern Kentucky to North Carolina...
Multiple MCVs, including across far south-central Missouri and
southeast Kansas at midday, will influence the region as they
progress east-southward generally toward Kentucky and Tennessee.
Related flow enhancement is evident in regional WSR-88d VWP data,
and particularly in the 12z Lamont, OK observed sounding (40+ kt
4-9km AGL). See Mesoscale Discussion 1346 for additional short-term
details.
These MCVs will influence and semi-focus thunderstorm development
within a moist and increasingly unstable boundary layer from the
southeast Missouri/northeast Arkansas border vicinity into Kentucky
and Tennessee. This includes the possibility of some supercells and
well-organized clusters in the presence of 35-40 kt effective shear.
Pockets of wind damage will be the most common risk, but some
tornado potential will exist as well. Additional severe storms
capable of wind damage are also expected farther eastward into the
Carolinas this afternoon through around mid-evening.
...Texas Panhandle/West Texas late this afternoon/evening...
Though forcing for ascent will be weak at best this far south,
strong surface heating/mixing along the lee trough/dryline could
support high-based thunderstorm development late this afternoon.
Inverted-V profiles will favor the potential for isolated severe
outflow gusts of 60-75 mph.
..Guyer/Supinie.. 06/27/2026
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Jun 27 2026
Valid 272000Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
TENNESSEE VALLEY TO THE CAROLINAS...
...SUMMARY...
Severe thunderstorms are likely today across the northern High
Plains including northeast Wyoming and eastern Montana into the
western Dakotas, with storms capable of very large hail, very strong
outflow winds (80+ mph), and tornadoes late this afternoon into
tonight.
...20Z Update...
The previous forecast remains on track, and only minor adjustments
were made with this update. The ENH risk was expanded slightly
southwestward in northeastern WY, where several discrete supercell
have evolved off the Bighorn Mountains -- posing a risk of large to
very large hail.
In western ND, the CIG1 tornado area was extended slightly
northward. Continued diurnal heating amid upper 60s dewpoints will
yield moderate-strong surface-based buoyancy and minimal inhibition.
Backed surface winds beneath strengthening flow aloft will
contribute to favorably curved hodographs. Any storms that can form
or move into this environment will conditionally support a strong
tornado.
Farther east, the SLGT risk was expanded northward in the lower OH
Valley. Here, diurnal heating/destabilization of a very moist air
mass (upper 70s dewpoints) will continue to support loosely
organized thunderstorm clusters capable of producing widely
scattered damaging winds this afternoon.
..Weinman.. 06/27/2026
.PREV DISCUSSION... /ISSUED 1142 AM CDT Sat Jun 27 2026/
...Northern High Plains this afternoon into tonight...
A rather active severe-weather scenario is anticipated regionally
later today, including the potential for intense/locally significant
severe storms. A lead shortwave trough/speed max will continue to
approach through late today, with the exit region of a strong
upper-level jet overspreading the region including 50+ kt
southwesterlies above 5km AGL. Boundary-layer dewpoints in the 60s F
will continue to spread northward regionally, to the east of a
deepening surface low across northeast Wyoming toward the far
western Dakotas, and a sharpening lee trough/dryline across a more
prevalent north/south extent of the High Plains. This low-level
moistening will occur beneath a plume of steep mid-level lapse rates
emanating from the Great Basin and north-central Rockies.
Initial surface-based development is expected near the surface
low/trough near the Big Horn Mountains toward the
Wyoming/Montana/North Dakota border vicinity. The maturing stronger
initial storms will almost certainly be supercellular owing to
moderate to large CAPE and a strong wind field. The risk for large
to very large hail (2-3 inches in diameter) is greatest near this
aforementioned border region where supercells are forecast early in
the convective life cycle, although additional/somewhat more
discrete development will also likely occur a bit later farther
southeastward across northwest South Dakota.
A few tornadoes are also possible particularly in the more
moisture-rich environment near the surface triple point, but
relatively large temperature-dewpoint spreads and a transition to
upscale growth may temper the tornado threat, particularly with
northward extent either side of the Montana/North Dakota border
vicinity. As more storms develop leading to storm mergers and
coalescing outflow, a linear cluster will likely develop into a
maturing/accelerating bow echo into western North Dakota this
evening, with significant/intense thunderstorm winds (80+ mph)
possible.
Severe storms will likely develop eastward tonight across the
Dakotas, and prior to that, diurnally enhanced, but more isolated
intense, development is plausible as far south as western Nebraska
with large hail and damaging winds.
...Northern Intermountain West including northern UT/western WY...
Influenced by a lead shortwave trough/speed max associated with the
prominent upper-level trough centered over the Pacific Northwest,
strong to locally severe thunderstorm potential will probably exist
early today. The prolifically strong wind field and modest
destabilization will tend to focus today across northern Utah,
southeast Idaho into western Wyoming, including the Star Valley
vicinity. Severe-caliber wind gusts and some hail may occur.
...Mid-South/Tennessee/southern Kentucky to North Carolina...
Multiple MCVs, including across far south-central Missouri and
southeast Kansas at midday, will influence the region as they
progress east-southward generally toward Kentucky and Tennessee.
Related flow enhancement is evident in regional WSR-88d VWP data,
and particularly in the 12z Lamont, OK observed sounding (40+ kt
4-9km AGL). See Mesoscale Discussion 1346 for additional short-term
details.
These MCVs will influence and semi-focus thunderstorm development
within a moist and increasingly unstable boundary layer from the
southeast Missouri/northeast Arkansas border vicinity into Kentucky
and Tennessee. This includes the possibility of some supercells and
well-organized clusters in the presence of 35-40 kt effective shear.
Pockets of wind damage will be the most common risk, but some
tornado potential will exist as well. Additional severe storms
capable of wind damage are also expected farther eastward into the
Carolinas this afternoon through around mid-evening.
...Texas Panhandle/West Texas late this afternoon/evening...
Though forcing for ascent will be weak at best this far south,
strong surface heating/mixing along the lee trough/dryline could
support high-based thunderstorm development late this afternoon.
Inverted-V profiles will favor the potential for isolated severe
outflow gusts of 60-75 mph.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1221 PM CDT Sat Jun 27 2026
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE DAKOTAS INTO NORTHERN MINNESOTA...
...SUMMARY...
Severe thunderstorms are possible from the northern Plains into
parts of the Upper Midwest on Sunday. Large to very large hail and
severe winds are the primary hazards.
...Northern Plains/Upper Midwest...
A challenging forecast scenario is expected on Sunday across
portions of the Dakotas into the Upper Midwest. Upper ridging is
expected to amplify over the Mid/Upper MS Valley and western Great
Lakes vicinity. This will result in capping concerns across the
region owing to height rises and warming aloft, especially from the
eastern Dakotas into the Upper Midwest. However, surface troughing
will sharpen and extend southward across the central Dakotas into
the central Plains. Meanwhile, a warm front/moisture gradient will
extend southeastward from northern MN into WI and the southern Lake
Michigan vicinity. Overnight, a surface low is forecast to mildly
deepen somewhere from western NE into SD. Forecast guidance
continues to show uncertainty in the evolution of this feature.
Southeasterly low-level flow will transport rich boundary layer
moisture westward across the region, with dewpoints in the mid 60s
to near 70 F common. A plume of steep midlevel lapse rates will
overspread the Red River and Upper MS Valley during the day, while
lapse rates further west steepen during the evening/overnight. This
will result in corridors of moderate to strong instability within
the warm sector to the east of the surface trough and south of the
warm front. However, given the building upper ridge, capping may
persist across the region, limiting potential for surface-based
convection.
Storms are expected to be ongoing Sunday morning across the eastern
Dakotas and will spread east through the day. While this activity
may be elevated, large hail is possible. A southerly low-level jet
is expected to persist through the daytime, and if storms can become
near-surface based, some damaging wind potential also would exist.
It is unclear how far east this convection may persist as it crests
the building upper ridge.
Overnight, convection is expected to develop near the surface
low/trough on the leading edge of a strong southerly low-level jet
across western or central SD. This activity may be elevated, but
will likely initially be supercell mode with an attendant risk for
large to very large hail. If convection grows upscale, some wind
risk is also possible, but this is more uncertain given capping
concerns.
...Southern Mid-Atlantic...
An MCV is expected to move across the NC vicinity on Sunday. Ahead
of this feature, a seasonally very moist and moderately unstable
airmass will be in place. Deep-layer flow will be modest, but the
MCV may locally enhance vertical shear and provide support for a
band of forward propagating convection moving off the higher terrain
during the after and early evening. Sporadic strong/damaging wind
gusts will be possible with these storms.
...Southern Plains...
A dryline will be oriented from western KS into southwest TX Sunday
afternoon/evening. Strong heating is expected along the boundary
along with sufficient dryline convergence. Deep boundary
circulations and a narrow corridor of moderate instability will
support isolated storm development. Strong downburst/outflow winds
will be possible with these storms as generally weak vertical shear
limits stronger updrafts longevity/organization.
..Leitman.. 06/27/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0217 PM CDT Sat Jun 27 2026
Valid 291200Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN AND CENTRAL PLAINS INTO THE UPPER MIDWEST...
...SUMMARY...
Severe thunderstorms are possible from parts of the central/northern
Plains into the Upper Midwest on Monday. Large hail and severe winds
are the primary concerns.
...Central/Northern Plains to Upper Midwest...
The forecast for Monday remains uncertain with forecast guidance
depicting a wide envelop for severe potential across portions of the
Missouri Valley into the Upper Midwest.
At the large scale, an upper ridge will persist from the central
Gulf Coast northward to the Upper Great Lakes. Further west, a
shortwave upper trough is forecast to eject from the central Rockies
into Manitoba/western Ontario. This will bring a belt of enhanced
mid/upper southwesterly flow across the northern Plains and Upper MS
Valley. At the surface, low pressure or an MCV over the Dakotas will
lift generally northeast while a trough/surface front extends
southward across the eastern Dakotas. The evolution of these
features is uncertain, with some guidance lifting the low and any
accompany severe risk quickly northward into Canada early in the
day. Other guidance is slower and further south, favoring a corridor
of severe potential across the eastern Dakotas and MN during the
day. While these details remain a question mark, a very moist
airmass will be in place with strong to extreme instability
forecast. Depending on mesoscale details, an all-hazards severe risk
could develop - though damaging wind and large hail appear most
likely at this time. Given uncertainty, outlook changes are modest
with this update.
..Leitman.. 06/27/2026
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