RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Jun 29 2026
Valid 291200Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
NORTHERN PLAINS AND UPPER MIDWEST...
...SUMMARY...
Severe thunderstorms are possible from parts of the northern Plains
into the Upper Midwest today. Large hail and severe winds are the
primary concerns, though a couple of tornadoes may also occur.
...Synopsis...
A shortwave trough will advance eastward from the northern Rockies
into the northern Plains today. At the surface, a low will move
northward out of Nebraska into the Dakotas, with a cold front/dry
line extending southward to a secondary low across the central
Plains. Thunderstorm activity is likely to be ongoing at the start
of the period near the northern surface low across portions of the
Dakotas. Additional thunderstorm activity is expected in the wake of
the morning convection near the warm front lifting across North
Dakota into Minnesota and near the cold front back into portions of
the Mid-Missouri Valley and central Plains.
...Dakotas/Mid-Missouri Valley/Upper Midwest...
Elevated supercell activity is likely to be ongoing at the start of
the period across portions of the Dakotas near the surface low and
nose of the low-level jet axis. The environment will be
characterized by moderate to strong instability and strong deep
layer shear. Guidance suggests that this will have the potential to
produce large to very large hail and damaging wind.
As the low develops, a warm front will extend into North
Dakota/Minnesota by the afternoon. Evolution of the morning activity
remains uncertain, but it appears that additional storms will
develop near the warm front and back near the low/cold front into
the afternoon. Near the warm front, filtered heating through broken
low to mid-level cloud cover will allow for moderate instability by
the afternoon. A plume of steep low to mid-level lapse rates will
advect northward through the afternoon. The favorable thermodynamic
profiles and strong deep layer shear around 45-50 kts will support
potential for supercells. If these storms can become surface based,
they will be capable of all hazards.
Back west near the cold front/low, initial supercells are possible
by the afternoon. These will have potential primarily for large hail
and damaging wind. Boundary parallel deep-layer shear will likely
lead to clustering/upscale growth with time. Strong to extreme
instability is expected ahead of the cold front across portions of
the western Dakotas into the Midwest. As the low-level jet increases
into the evening, it is possible that a corridor of more favorable
damaging wind potential (including significant gusts 75+ mph) may
evolve. For now, confidence in convective evolution is low with a
few CAMs suppressing convection towards the evening along the front
amid the strong EML until later in the evening around 06z.
...Kansas/Oklahoma/Texas...
Isolated high-based thunderstorms are possible near the dryline in
Kansas/Oklahoma/Texas. Moderate instability is expected within this
region with generally weak deep layer shear. This will likely keep
more widespread severe potential low. However, a few stronger storms
may be capable of strong winds given deeply mixed profiles. For now,
this potential remains too isolated to include probabilities.
..Thornton/Chalmers.. 06/29/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0106 AM CDT Mon Jun 29 2026
Valid 301200Z - 011200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHERN WISCONSIN
INTO THE UPPER PENINSULA OF MICHIGAN...
...SUMMARY...
Severe thunderstorms will be possible from parts of the central High
Plains into the Upper Midwest, and across parts of the Northeast on
Tuesday.
...Synopsis...
An upper low will be present in the Canadian Prairies with a belt of
stronger mid-level flow extending into the Upper Midwest. The
amplified upper ridge in the Midwest/East will be somewhat
suppressed as a result. A stalled surface boundary will be present
from the central High Plains into the Upper Midwest. Moderate to
strong mid-level northwesterlies will be present across the
Northeast with possible MCVs/shortwaves moving into the region.
...Mid-Missouri Valley into Upper Midwest...
Convection that occurs in Minnesota overnight Monday into early
Tuesday is expected to weaken as it moves eastward. Given the
weakening and veering low-level jet, it does not appear this
activity will have much of an impact on the environment in northern
Wisconsin into the Upper Peninsula of Michigan. A stalled surface
boundary will be located from northern Nebraska into Minnesota and
northwest Wisconsin. Very rich moisture (mid/upper 70s F dewpoints)
will exist in the warm sector. With mid-level lapse rates of 7.5-8
C/km, strong to extreme buoyancy will develop by the afternoon. With
the main upper low in the Canadian Prairie, large-scale ascent will
be subtle/nebulous. That said, convective temperatures should be
reached at least locally with additional lift expected from lake
breeze boundaries. Most models, including both global/regional
models and CAMs, suggest development is probable from parts of
northern Wisconsin into the Upper Peninsula. Effective shear of
40-50 kt will promote some storm organization. However, magnitude of
buoyancy along with modest low-level flow will likely result in
storms becoming outflow dominant. A targeted Slight Risk has been
added for this potential. Damaging winds are the most likely hazard
with this activity, but isolated large hail could also occur.
Farther southwest into southern Minnesota/Iowa/Nebraska/South
Dakota, storm coverage is much less certain. There could be an
increase in thunderstorm activity as the low-level jet increases
during the evening. Should this occur, damaging winds and perhaps
isolated large hail would be possible. Shear will be weaker in these
areas and the severe threat will likely remain marginal/isolated.
...Northeast...
Questions remain as to the timing of MCV/convection moving out of
Canada. Given the potential for early precipitation to occur and
limit surface-based instability, the Marginal Risk has been
maintained for this outlook. Nevertheless, the environment will be
favorable for strong to severe storms. Effective shear is expected
to be around 50 kt. Damaging winds and large hail are likely the
main risks; however, if storm mode is more cellular, a greater
tornado risk could also be present. Trends in guidance will need to
be monitored.
...Colorado/Kansas/southwest Nebraska...
A modest lee trough will promote moisture advection into the central
High Plains. A subtle shortwave trough moving through the central
Rockies may aid in storm development. The timing of storm
development is not certain, but most guidance would suggest this
occurs at or after 00Z. Steep mid-level lapse rates and moderate
deep-layer shear will promote organized storms that will be capable
of large hail (isolated to around 2 in.) and severe winds. Low-level
shear will be enhanced near the surface trough/low, but concerns
over low-level thermodynamics limit confidence in a tornado threat.
..Wendt.. 06/29/2026
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