URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 666
NWS Storm Prediction Center Norman OK
640 PM CDT Fri Sep 11 2026

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Southwestern into North-Central Minnesota
  Eastern South Dakota

* Effective this Friday evening from 640 PM until 1000 PM CDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible
  A tornado or two possible

SUMMARY...Scattered thunderstorms are forecast to continue to
develop and intensify this evening.  The stronger storms will be
capable of a risk for large hail (1 to 2 inches in diameter) and
severe gusts (60 to 70 mph).  A tornado is possible early this
evening if a supercell can be maintained, and before additional
storms coalesce and outflow becomes more prevalent.

The severe thunderstorm watch area is approximately along and 45
statute miles east and west of a line from 60 miles north of
Brainerd MN to 50 miles south of Brookings SD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU6).

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
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
26025.

...Smith

STATUS FOR WATCH 0666 HAS NOT BEEN ISSUED YET

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0300 PM CDT Fri Sep 11 2026

Valid 112000Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MIDWEST...

...SUMMARY...
Scattered severe thunderstorms capable of producing large hail,
(some 2+ inches), damaging winds, and a couple of tornadoes are
expected late this afternoon and tonight across parts of the Upper
Midwest. Thunderstorm development is more uncertain farther south
into the central Plains, where a risk for large hail and severe
gusts may exist late this afternoon into the evening.

...20Z Update...
The ongoing forecast remains mostly on track with most areas
remaining unchanged. Given the signal for the cold front to push
into northern Kansas by early Saturday morning, along with at least
a modest low-level jet, marginal wind/hail probabilities have been
extended into more of central Kansas for the conditional potential
of severe storms overnight.

..Wendt.. 09/11/2026

.PREV DISCUSSION... /ISSUED 1127 AM CDT Fri Sep 11 2026/

...Upper Midwest/central Plains...
An eastward-progressive belt of quasi-zonal westerlies exists over
the northern half of the CONUS, to the south of upper troughing over
the Canadian Prairies/central Canada, and the east of the amplifying
upper trough off the coastal Pacific Northwest. Weak frontal wave
development will occur from eastern South Dakota into Minnesota as a
cold front spreads eastward, with the front eventually overtaking a
pre-frontal trough/dryline across the central Plains.

A narrow corridor of 60s F surface dewpoints are in place ahead of
the cold front/dryline, with diurnal heating aiding moderate
destabilization along with steepened mid-level lapse rates. Minimal
MLCIN is expected along/ahead of the front in far northeast South
Dakota/western Minnesota into/just after peaking heating. Convective
development appears likely in this time frame across this region,
especially across Minnesota, owing to sufficient low-level
convergence along the front coupled with forcing for ascent
associated with the mid-level shortwave trough.

Strongly veering and gradually strengthening winds with height
through low/mid-levels, and 35-45 kt of deep-layer shear will easily
support organized convection. Initial supercells should pose a
threat for large hail (isolated 2+ inches possible), but convective
mode will probably trend towards clustering fairly quickly given the
presence of the cold front and strengthening low-level jet this
evening. Any supercells that can remain at least semi-discrete into
the early evening may also have a tornado threat with greater
low-level shear forecast in this time frame. Scattered
severe/damaging winds should occur with any clusters or bowing line
segments that can develop and spread eastward through the evening.
However, the wind threat will likely wane with eastward extent
across Minnesota into western Wisconsin by late this evening given
the narrow zone of destabilization forecast.

Farther southwest, convective initiation and overall thunderstorm
coverage from southeast South Dakota/southwest Minnesota
southwestward into Nebraska and northern Kansas are more uncertain
and probably more limited/conditional late this afternoon and
evening, as the better forcing for ascent with the shortwave trough
will remain regionally focused to the north. Still, a favorable
thermodynamic environment and sufficient (25-35 kt) deep-layer shear
would conditionally support severe hail/wind with any thunderstorms
that can develop and be sustained.

...Mid-South/Tennessee Valley/Carolinas and Virginia...
Multiple convectively augmented mid-level perturbations remain
evident at midday in satellite/radar imagery, including over the
Ozarks as well as the middle Gulf Coast in vicinity of southern
Alabama. A stalled surface front extending from the ArkLaTex
east-northeastward into the Tennessee Valley and Virginia will
provide a focus for thunderstorms. Generally speaking, expectations
are for generally disorganized/pulse-type convection to pose a
threat for occasional damaging winds as diurnal heating destabilizes
the boundary layer and steepens low-level lapse rates. However, a
modest enhancement to mid-level flow across parts of the Mid-South
(25 kt mid-levels per Little Rock AR WSR-88D VWP), as well as
Virginia, could promote a couple of loosely organized clusters with
a bit more of a focused damaging wind threat.

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0221 PM CDT Fri Sep 11 2026

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHEASTERN STATES...AND NORTHERN PLAINS...

...SUMMARY...
Strong storms accompanied by at least some risk for severe weather
may occur across parts of the Northeast, and across parts of the
north central Great Plains Sunday into Sunday night.

...Ohio into the Northeast...
A large upper low/trough will push across eastern Canada on Sunday,
with a strong speed max aloft spreading across the Great Lakes late
in the day. A cold front will push toward the OH Valley and Lower
Great Lakes late in the day, with a moist and marginally unstable
air mass ahead of it. Areas of heating and lift near the boundary
should support scattered afternoon/evening storms, and deep-layer
shear of 30 to perhaps 40 kt could support a degree of organization.
Lapse rates aloft appear to be poor overall, suggesting only a
Marginal Risk of damaging gusts or hail will exist.

...Northern Plains...
High pressure will move from the northern Plains to the Upper Great
Lakes as shortwave ridging occurs over the Plains during the day. A
compact yet deep upper low is then forecast to move into the
northern Rockies, with height falls increasing over the northern
High Plains Sunday night.

The steeper low-level lapse rates will be confined to the higher
terrain from east-central WY to the Front Range in CO, with
generally stable low levels to the east due to high pressure. After
a days worth of heating, isolated surface-based storms may occur
late over eastern WY, with additional activity developing within the
warm advection regime as the low-level jet increases over the
central Plains. The overall threat appear minimal, and likely in the
form of marginal hail.

..Jewell.. 09/11/2026

Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0251 PM CDT Fri Sep 11 2026

Valid 121200Z - 131200Z

...Great Basin and parts of the Sacramento Valley and adjacent
foothills...
A robust upper low and associated 65-75 knot mid-level jet moving
into Pacific Northwest and northern CA will promote elevated fire
weather concerns across much of the Great Basin and portions of the
Sacramento Valley and adjacent foothills/Coastal Range on
D2/Saturday. West/southwest winds of 15-20 mph will evolve across
much of NV, southern ID by Saturday afternoon while RH reductions of
10-15% will be common central/southern NV. A corridor of enhanced
southwesterly winds of 20-30 mph in closer vicinity to the mid-level
jet is expected across far northeastern CA, far northwest NV and
southeastern OR. However, fuel receptiveness across the region will
remain subdued due to recent moisture and afternoon RH closer to
20-25% should insulate impacts from an otherwise near-critical
meteorological environment.

Elevated highlights have been introduced into portions of the
Sacramento Valley and Coastal Range vicinity for Saturday. Onshore
flow accelerates through Saturday as the upper low and associated
stronger flow aloft push into the region. The onshore flow should
inhibit critically low RH of 15% or less from developing Saturday
afternoon. However, west winds of 10-20 mph (localized wind gusts of
40 mph in favored Coastal Range terrain gaps) will sustain an
overall fire weather threat within sufficiently receptive fuelscape.

..Williams.. 09/11/2026

.PREV DISCUSSION... /ISSUED 0207 AM CDT Fri Sep 11 2026/

...Synopsis...
An upper low is forecast to move into portions of the Pacific
Northwest on Saturday with a fairly strong 70 kt jet streak. As this
jet streak begins to enter the Great Basin, the cross-range flow and
boundary layer mixing will result in dry and breezy conditions
supporting Elevated fire-weather highlights. 


...Northern Nevada into far southern portions of Oregon and Idaho...

Westerly surface winds should become fairly gusty, reaching 20-25
MPH and relative humidity of 10-15%. However, fuels are generally in
the vicinity of the 50th-60th annual ERC percentiles, suggesting a
lack of receptiveness to wildfire ignition and spread. In spite of
the meager fuels, meteorological conditions will warrant at least
Elevated highlights owing to the strong surface winds.

...Please see www.spc.noaa.gov/fire for graphic product...

Day 3-8 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0442 PM CDT Fri Sep 11 2026

Valid 131200Z - 191200Z

...Synopsis...
An upper trough will translate east-northeastward from the Pacific
Northwest and Northern Rockies on Day 3/Sunday into the Upper
Midwest by Day 4/Monday. In response, broader dry west/southwest
flow develops across portions of the Great Basin on Day 3/Sunday,
with fire weather concerns potentially lingering into parts of the
northern Rockies on Day 4/Monday. Another mid/upper trough enters
the Pacific Northwest on Day 5/Tuesday, possibly bringing dry and
breezy conditions back to the Great Basin. A stagnant upper-level
ridge over the southern CONUS will continue to promote above normal
temperatures across much of the southern/central Plains through next
week. Fire weather concerns east of the Continental Divide next week
should be confined to portions of the Southern Plains where daily
southerly winds and dry fuels align although forecast uncertainty in
RH reductions limits predictability of fire weather impacts.

...Day 3/Sunday - Great Basin into southwestern Montana...
Pre-frontal southwest winds of 15-20 mph amid a well mixed boundary
layer and minimum RH of around 15% will present a broad fire weather
threat to the Great Basin into portions of ID and southwest MT on
Day 3/Sunday. As the upper-trough and related dry cold front shift
eastward, a west to northwest wind shift will present an additional
fire weather hazard to existing wildfires, before cooler
temperatures and higher RH provide some reprieve Sunday night. 40%
critical probabilities have been added to cover this threat.

...Day 4/Monday...
...Wyoming/Northern High Plains...
A fire weather threat may be reintroduced into portions of WY and
the northern High Plains as the trough across the Pacific Northwest
makes eastward progress into the Northern Plains. However, some
uncertainty exists regarding the deeper subtropical moisture plume
over the Four Corners and its eventual northward extent. Expanding
leeward surface troughing across the northern/central Plains will
promote the stronger low-level westerly flow across southern WY
while dry and breezy conditions ahead of a cold front are possible
across southern MT/northern WY and adjacent SD, but potential
rainfall could mitigate these concerns.

...Southern Plains...
Persistent south to southwest flow at the surface under a stagnant
upper ridge is expected across portions of the southern Plains next
week. Fuels across western OK and northwestern TX remain dry and
receptive (ERCs near the 90th percentile) with minimal rainfall
observed recently. South winds of 10 to locally 20 mph and the dry
fuels will likely align, although forecast uncertainty in RH
reductions each afternoon precludes introduction of critical
probabilities for this outlook.

..Williams.. 09/11/2026

...Please see www.spc.noaa.gov/fire for graphic product...