WW 412 SEVERE TSTM SD 290300Z - 291100Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 412
NWS Storm Prediction Center Norman OK
1000 PM CDT Sun Jun 28 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southwest and central South Dakota
* Effective this Sunday night and Monday morning from 1000 PM
until 600 AM CDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 90
mph likely
Scattered large hail and isolated very large hail events to 3
inches in diameter likely
A tornado or two possible
SUMMARY...A cluster of severe storms, including embedded supercells,
is expected to form and move northeastward into central South Dakota
through daybreak. The storms will be capable of producing very
large hail up to 3 inches in diameter, significant severe gusts of
up to 90 mph, and possibly a tornado or two.
The severe thunderstorm watch area is approximately along and 70
statute miles east and west of a line from 35 miles north northeast
of Pierre SD to 75 miles south of Philip SD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
3 inches. Extreme turbulence and surface wind gusts to 80 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
23035.
...Thompson
MD 1374 CONCERNING SEVERE THUNDERSTORM WATCH 412... FOR MUCH OF CENTRAL SOUTH DAKOTA
Mesoscale Discussion 1374
NWS Storm Prediction Center Norman OK
0302 AM CDT Mon Jun 29 2026
Areas affected...much of central South Dakota
Concerning...Severe Thunderstorm Watch 412...
Valid 290802Z - 291000Z
The severe weather threat for Severe Thunderstorm Watch 412
continues.
SUMMARY...Storms over south-central South Dakota are expected to
become an intense complex over the next couple hours, producing
winds of 75-90 mph and large hail across central parts of the state.
DISCUSSION...Earlier supercells have merged near the cold front and
surface low over southwest SD, with recent radar trends indicating
the early stages of upscale growth into a compact but significantly
severe MCS. Aside from the supercell over Bennett County SD, radar
also shows a warm advection wing developing east/northeast of it,
with additional development south of this cell along the cold front.
This evolution is taking place near a substantial 850 mb theta-e
gradient, with MUCAPE up to 4000 J/kg along and south of the surge.
Given recent trends, strong instability and steep lapse rates aloft,
and a favorable low-level jet, confidence is increasing that this
complex will strengthen, and possible accelerate northeastward
through the morning hours. Additional watches may be required
downstream into more of northern/northeast SD and southeast ND as
the scenario evolves.
..Jewell.. 06/29/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...ABR...LBF...UNR...
LAT...LON 42900231 43320213 43610187 44000134 44560086 45220005
45179925 44989881 44579880 43819925 43180022 42920144
42760224 42900231
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
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
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
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0234 AM CDT Mon Jun 29 2026
Valid 011200Z - 021200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN PARTS OF
THE CENTRAL PLAINS INTO THE UPPER MIDWEST...AND PARTS OF THE
NORTHEAST...
...SUMMARY...
Isolated strong to severe storms will again be possible from the
central Plains into the Upper Midwest as well the Northeast on
Wednesday. Severe wind gusts and large hail are the main concerns.
...Synopsis...
The upper-level pattern across the CONUS will not significantly
change from Tuesday into Wednesday. A broad trough in the West will
maintain modest to moderate mid-level flow across the Plains into
the Upper Midwest. Some stronger mid-level flow is possible in the
Upper Great Lakes vicinity due to the main synoptic trough displaced
to the north in Canada. Moderate northwesterly winds aloft will
persist in the Northeast as well. Strong to extreme buoyancy will
develop during the afternoon from the Upper Midwest into the
Northeast with a very moist airmass beneath the upper ridge.
...Central Plains into the Upper Midwest...
A stalled surface boundary will may eventually make modest northward
progress as a weak surface trough develops in the central/northern
Plains. Models suggest convection will be ongoing early in the
morning in the Nebraska/South Dakota vicinity. Given the strong
low-level jet expected, it is not clear if this convection will
weaken during the morning or continue eastward into an increasingly
unstable airmass. Depending on how that early activity evolves,
there is potential for another round of convection to develop along
the boundary in the Upper Mississippi Valley. This may be aided by a
subtle shortwave trough moving northeast. In either case, MCS
development is possible with time. Damaging winds and isolated large
hail are possible, though there may end up being a corridor of
greater wind damage potential should an MCS develop. Greater severe
probabilities may be needed as confidence increases.
...Northeast...
Forcing for ascent will be more nebulous on Wednesday. Even so, the
very unstable environment will promote a risk of strong/damaging
downburst winds as well as isolated large hail. Given the
uncertainty in storm coverage, only low severe probabilities have
been added.
..Wendt.. 06/29/2026
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Jun 29 2026
Valid 021200Z - 071200Z
...DISCUSSION...
The broad trough in the West and ridge in the East will persist
through the remainder of the week. A moist airmass across much of
the CONUS east of the Rockies will support repeated days of
convective activity. Large-scale forcing will remain weak, but
shortwave troughs emanating from the western trough will promote
development within the Plains and the Upper Midwest where a stalled
surface boundary will be positioned. Both Thursday and Friday show
potential for MCS development from Nebraska into the Dakotas. Friday
will likely have a more prominent shortwave trough as a lifting
mechanism. Where this potential severe weather will be focused is
not certain given the expected convection that will occur each day
prior. For Saturday, some models show the shortwave trough moving
into the Upper Midwest where another round of convection may occur.
Severe probabilities are certainly possible in the coming days as
confidence continues to increase.
Another area to watch this week will be the Northeast. Here,
stronger northwesterly flow at mid levels will continue into part of
the weekend. Depending on how the shortwave trough evolves in the
Upper Midwest, this feature may eventually move into the Northeast
and promote thunderstorm development late this weekend into next
week. Predictability remains too low for highlights, however.
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0156 AM CDT Mon Jun 29 2026
Valid 291200Z - 301200Z
...Synopsis...
Longwave upper troughing will remain positioned across the
Intermountain West today. While the strongest mid-level flow will
transition northeastward in tandem a northeastward-ejecting
mid-level shortwave, a second mid-level shortwave rotating
southeastward across California and the western Great Basin will
help maintain enhanced mid-level flow across much of the Great Basin
and Southwest. Combined with a persistent dry air mass and lingering
enhanced mid-level flow, this will continue to support expansive
fire weather concerns across portions of the Great Basin and
Southwest today.
...Southwest/Four Corners region...
The aforementioned enhanced mid-level flow continuing to linger
across portions of the Southwest and Four Corners region will
support a corridor of sustained southwesterly surface winds of 15-20
mph this afternoon. With RH values forecast in the 10-15% range and
several days of antecedent dry/windy conditions exacerbating fuel
dryness/receptiveness (ERCs in the 80th to 95th percentiles or
greater), this will promote elevated to locally critical fire
weather concerns across much of Arizona, southeastern Utah,
western/central Colorado, western/central New Mexico, and southern
Wyoming. Deep boundary layer mixing will also support occasional
wind gusts to 30-35 mph across much of this region.
The best chance for locally critical conditions to emerge will
extend from central Colorado southward into north-central New
Mexico, where ERCs are noted to range from the 90th to 99th
percentiles. Modestly stronger mid-level flow is forecast to linger
later into the afternoon across this region, which should promote
marginally stronger sustained surface winds and occasional wind
gusts of 30-40 mph. An upgrade to Critical was considered for this
area, but uncertainty remains regarding a longer duration and
broader overlap of 20+ mph sustained winds and RH less than 15%. A
targeted upgrade could be needed in the D1 update should
guidance/observations indicate the development of critical wind/RH
conditions across a more widespread area within this region.
..Chalmers.. 06/29/2026
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0158 AM CDT Mon Jun 29 2026
Valid 301200Z - 011200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHEASTERN
ARIZONA...NORTHWESTERN NEW MEXICO...WESTERN COLORADO...AND EASTERN
UTAH...
...Synopsis...
Amid persistent longwave troughing centered over the Intermountain
West, an embedded shortwave trough will pivot northeastward across
portions of the Great Basin and Colorado River Valley on Tuesday.
With several preceding days of dry/breezy conditions across the
region, this will continue to support expansive fire weather
concerns across portions of the Great Basin/Southwest.
...Four Corners region into eastern Utah/western Colorado...
As the aforementioned shortwave rounds the base of the longer
wavelength trough positioned across the West, a mid-level jet streak
is forecast to overspread the Four Corners/Colorado Plateau. Latest
high-res and ensemble guidance suggests that this will support a
corridor of enhanced (sustained 20-25 mph with occasional gusts of
30-35 mph) south-southwesterly winds from northeastern
Arizona/northwestern New Mexico into eastern Utah and western
Colorado amid minimum RH values of 5-10%. With several days of
dry/breezy conditions across the region, ERCs span from the 80th to
98th percentile (locally greater). This combination of dry/receptive
fuels and wind/RH conditions is expected to support critical fire
weather conditions across portions of the Four Corners region and
Colorado Plateau. A broader area of elevated fire weather concerns
is forecast across adjacent regions of the Great Basin, Southwest,
and the immediate lee of the Sangre de Cristos.
..Chalmers.. 06/29/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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