URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 637
NWS Storm Prediction Center Norman OK
440 PM CDT Sun Aug 30 2026

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Central North Dakota
  North-Central South Dakota

* Effective this Sunday afternoon and evening from 440 PM until
  1100 PM CDT.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 75
    mph likely
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A squall line will move east across the northern portion
of the severe thunderstorm watch with a mix of cells and line
segments farther south near the Dakotas' state border.  The main
threats with the stronger storms will be severe gusts 60 to 75 mph
and perhaps isolated large hail with the stronger cores.

The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 55 miles north northeast
of Minot ND to 45 miles southwest of Mobridge SD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU7).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 636...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
25020.

...Smith

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 636
NWS Storm Prediction Center Norman OK
125 PM MDT Sun Aug 30 2026

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Far Eastern Montana
  Western North Dakota
  Northwestern South Dakota
  Far Northeastern Wyoming

* Effective this Sunday afternoon and evening from 125 PM until
  900 PM MDT.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 75
    mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...Ongoing line of storms moving across northeast Montana has
recently produced gusts over 60 mph. This line is expected to
continue northeastward this afternoon. Additional thunderstorm
development is anticipated across southeast Montana and adjacent far
northeastern Wyoming. This activity is expected to gradually
strengthen, potentially producing strong to severe wind gust from 65
to 80 mph as it moves eastward. Thunderstorm development is also
possible along a cold front is western North Dakota. Large hail and
strong gusts are possible with these storms.

The severe thunderstorm watch area is approximately along and 85
statute miles east and west of a line from 40 miles north northeast
of Williston ND to 75 miles east of Gillette WY. 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
1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
24030.

...Mosier

STATUS FOR WATCH 0637 HAS NOT BEEN ISSUED YET

STATUS REPORT ON WW 636

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 WNW RAP
TO 30 SE BHK TO 35 ESE GDV TO 15 NNW SDY TO 80 N ISN.

..LYONS..08/30/26

ATTN...WFO...BYZ...GGW...BIS...UNR...


STATUS REPORT FOR WS 636 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

NDC001-007-011-013-023-025-033-041-053-061-087-089-105-302340-

ND 
.    NORTH DAKOTA COUNTIES INCLUDED ARE

ADAMS                BILLINGS            BOWMAN              
BURKE                DIVIDE              DUNN                
GOLDEN VALLEY        HETTINGER           MCKENZIE            
MOUNTRAIL            SLOPE               STARK               
WILLIAMS             


SDC019-063-105-137-302340-

SD 
.    SOUTH DAKOTA COUNTIES INCLUDED ARE

BUTTE                HARDING             PERKINS             
ZIEBACH              


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.

Mesoscale Discussion 2177
NWS Storm Prediction Center Norman OK
0539 PM CDT Sun Aug 30 2026

Areas affected...the North Dakota and South Dakota Border

Concerning...Severe Thunderstorm Watch 636...637...

Valid 302239Z - 302345Z

The severe weather threat for Severe Thunderstorm Watch 636, 637
continues.

SUMMARY...An organized bowing segment with a history of significant
wind gusts will pose a threat for additional severe gusts (likely
peak 75-90 mph) across southern ND and northern SD this evening.

DISCUSSION...An organized bowing segment ongoing across portions of
Adams and Perkins Counties has a history of producing significant
wind gusts with a recent 100 mph measured at K2WX. Located along
southern portions of the developing squall line, this bowing
structure will continue east/northeastward around 50 kt into an
unstable and recovering air mass along the ND/SD border this
evening. Low-level lapse rates and strong mid-level westerly flow
remain favorable for severe gusts with peak gusts of 75-90 mph
possible. The enhanced cold pool may also support intensification of
the rest of the line this evening. This is supported by hires
RRFS/HRRR guidance which show peak gusts of 75+ mph possible with
southern portions of the line over the next 1-2 hours.

..Lyons.. 08/30/2026

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

ATTN...WFO...ABR...BIS...UNR...

LAT...LON   47060182 47240123 47190055 46960020 46670015 46060022
            45740055 45560232 45570273 45850283 46170274 46600237
            47060182 

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0246 PM CDT Sun Aug 30 2026

Valid 302000Z - 311200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
 EVENING FROM SOUTHEAST MONTANA AND FAR NORTHEAST WYOMING INTO THE
CENTRAL DAKOTAS...

...SUMMARY...
Severe storms capable of damaging wind gusts are possible across
portions of the northern Plains this afternoon and evening.

...20z Update...
Only minor changes were made to remove the Marginal Risk from behind
ongoing convection in eastern Montana. Otherwise, the D1 Convective
Outlook remains on track. See previous discussion and MCD #2174 for
more information.

..Thornton.. 08/30/2026

.PREV DISCUSSION... /ISSUED 1129 AM CDT Sun Aug 30 2026/

...Northern High Plains into the northern Plains...
Recent satellite imagery shows a well-defined shortwave trough
moving eastward across southern Saskatchewan and western MT/eastern
ID. A belt of stronger westerly flow aloft likely exists within the
base of this trough from eastern ID into western WY. Recent
mesoanalysis estimates 50 to 60 kt at 500 mb, but its actual
magnitude is uncertain. Showers and isolated thunderstorms are
already ongoing downstream of this wave, and the general expectation
is for these showers and thunderstorms to persist as the wave moves
eastward, eventually encountering a notably more unstable airmass
downstream.

Current surface observations show mid 60s dewpoints into the western
Dakotas, with upper 50s/low 60s dewpoints farther west in eastern
MT. Afternoon high temperatures are expected range from the low to
mid 80s along the MT/ND border into the low 90s farther south into
southwest SD. Despite relatively poor pre-frontal mid-level lapse
rates, the resulting temperature/dewpoint combination will support
MLCAPE ranging from around 500-1000 J/kg across eastern MT and the
western Dakotas to closer to 2000 J/kg across the central Dakotas.
Some low-level stability may linger, but should be overcome by the
strong forcing, and the development of a line of strong to severe
storms is anticipated. Strong to severe gusts will be the primary
risk, with some instance of gusts from 65 to 80 mph possible.
Maximum storm intensity and highest severe coverage is currently
forecast to occur from the ND/SD/MT border intersection vicinity
eastward into south-central ND and north-central SD. Decreasing
buoyancy is expected from the central Dakotas eastward, with
gradually decreasing storm intensity expected as the line of storms
moves into this region this evening.

...Central High Plains...
Increased coverage and depth of the thunderstorms across UT indicate
the presence of secondary area of ascent south of the primary
shortwave trough, perhaps tied to a convectively augmented vorticity
maximum. Expectation is for this vorticity maximum to progress
eastward, persisting across the central Rockies before entering
deeply mixed boundary-layer in place over the central High Plains.
High-based storm character coupled with steep low-level lapse rates
will support the development of strong outflow, and gusts from 60 to
75 mph are possible.

...UT/Western CO...
Thunderstorms are already ongoing from eastern UT into western CO,
and deep-layer vertical shear is already strong enough to support
organization within any more persistent updrafts. A few instances of
hail and/or damaging gusts are possible with this activity.
Additionally, considerable low-level moisture will remain over UT
today, leading to another round of strong to isolated severe
thunderstorms this afternoon. Deep-layer shear will remain
sufficient for rotating storms capable of damaging wind gusts and
hail. This additional activity should also spread into western CO
before weakening this evening.

...Central/Southern AZ...
Ample low-level moisture remains in place across much of AZ, with
upper 50s dewpoints across northern AZ increasing into the mid 60s
across southern AZ. Another day of afternoon thunderstorms is
anticipated as this moist airmass destabilizes amid strong diurnal
heating. High-based storms coupled with moderate buoyancy and steep
low-level lapse rates could result in a few strong to severe gusts
across the region this afternoon and evening.

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0234 PM CDT Sun Aug 30 2026

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM WESTERN NEW
YORK ACROSS PENNSYLVANIA AND INTO NEW JERSEY...

...SUMMARY...
Scattered strong to severe storms are possible Tuesday over parts of
New York, Pennsylvania and New Jersey. Isolated severe storms may
also extend westward into Nebraska.

...Synopsis...
A zone of moderate instability is forecast to stretch from the Upper
Midwest eastward into parts of NY, PA and NJ on Tuesday. This will
also be along a weak surface trough, where various areas of rain and
thunderstorms will exist throughout the period. Anticyclonic flow
aloft around the northern periphery of an upper ridge will yield
30-40 kt midlevel northwesterlies, and minor cooling aloft may occur
as embedded disturbances move across the Great Lakes and into the
Northeast.

...Northeast...
The greatest concentration of thunderstorms will be from NY into PA,
both during the day and overnight. Early day storms will be possible
from southern New England into NY, where elevated instability will
exist. Destabilization will then occur south of this zone and
possible outflows, with additional activity possible. Forcing for
ascent should remain relatively weak, but sufficient convergence
near any boundaries or an afternoon surface trough may support
redevelopment. Elongated mid to upper level hodographs suggest
cellular storm mode is possible, with hail and locally damaging
gusts most likely. Overnight, additional activity is forecast as
height falls occur upstream, and westerly winds at 850 mb maintain
theta-e. Several models suggest storms moving out of Ontario
overnight, with wind potential.

...Nebraska into northwest Iowa and vicinity...
Moderate southwest winds aloft will persist over this area, as
daytime heating yield moderate instability. Some of this area may be
affected by early day rain/storms, with boundary reinforcement.
Strong heating and a developing southerly low-level jet should
support new development, perhaps a supercell or two producing hail.
Storm coverage may then increase during the evening and spread
northeastward.

..Jewell.. 08/30/2026

Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0245 PM CDT Sun Aug 30 2026

Valid 311200Z - 011200Z

Minor changes were made to the existing Elevated area over far
northeastern CA and south-central OR. The latest forecast guidance
has maintained 15-20 mph southwest surface winds amid 10-20% minimum
RH across the drawn area. While coincident elevated winds and low
RHs may persist slightly farther east into the western Great Basin,
recent rainfall and cool temperatures have reduced fuels below
critical thresholds for now over much of NV.

Meanwhile, the trough axis progressing across the northern tier of
the CONUS on Day 2/Monday will lead to elevated westerly winds near
15-20 mph amid low RHs down to 20-25% over portions of western ND
and nearby areas. However, fuels remain marginally receptive
(especially given preceding precipitation possible on Day 1/Sunday)
across this area, leading to more of a curing event than an
immediate wildfire risk. Given the continued above normal
temperatures amid drier than normal conditions and periodic wind
events, this region will be watched closely as troughing continues
to impact the northern portion of the CONUS.

..Stearns.. 08/30/2026

.PREV DISCUSSION... /ISSUED 1231 AM CDT Sun Aug 30 2026/

...Synopsis...
A broad trough will persist across much of the West on Monday. A
compact shortwave trough will move through the Great Basin through
the day. In its wake, mid-level flow will relax before quickly
increasing again into Tuesday morning. At the surface, a broad and
modest surface trough will develop within the Northwest into the
northern Great Basin. A small zone of favorable overlap of 15-20 mph
winds with marginally lowered RH (15-20%) is forecast from northeast
California into south-central Oregon. Here, marginally elevated fire
weather concerns will exist during the afternoon given the very dry
fuels.

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

Day 3-8 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0444 PM CDT Sun Aug 30 2026

Valid 011200Z - 071200Z

...Synopsis...
A series of mid-level troughs will continue impacting the Pacific
Northwest and neighboring areas of the western CONUS throughout the
Extended Outlook time frame. This will leave the northwestern
quadrant of the CONUS under periodically strong southwest to
westerly flow throughout much of the forecast. Embedded disturbances
will continue to move through the persistent troughing and along the
northern periphery of the flattening/displaced upper-level ridge
centered over the Midwest US. This will deflect monsoonal moisture
to the south and east, but advect additional moisture onshore from
the eastern Pacific. The general consensus does favor continued well
below normal temperatures across the western third of the CONUS much
of the week along with increasing likelihood for multiple days of
accumulating rainfall over a good portion of the Pacific Northwest.

...Northwest, Northern Great Basin, and Northern California...
Dry southwest flow aloft associated with continual troughing over
the northwest CONUS will promote at least one more day of fire
weather concerns into mid-week. 40% Critical probabilities have been
maintained with minor adjustments for Day 3/Tuesday over
northeastern CA, northwestern NV, and southeastern OR. West to
southwest winds of 15-20 mph amid afternoon RH of 10-20% will
continue elevated fire weather concerns over this region. Below
normal surface temperatures will moderate the threat slightly, but
conditions will remain conducive to wildfire spread until a
significant precipitation event occurs. Increasing potential for
accumulating (widespread wetting) rainfall is introduced mid-week
over much of the Pacific Northwest.

...Central and Eastern Wyoming...
Persistent above normal temperatures and strengthening drought
conditions continue to promote fuel curing across central WY into
portions of the western Dakotas and far southeastern MT. These
antecedent conditions will combine with westerly winds (sustained at
15-20 mph) as trough passages continue, to result in at least
elevated wind/RH (minimums near 15-20%) combinations over this
region. Both ERCs and BIs will climb above their respective
90th-95th percentiles, indicating fuels receptivity is reaching
critical levels across the region where not hampered by significant
green up. Thus, the 40% Critical wind/RH probability was maintained
and expanded in areal extent slightly on Day 4/Wednesday with an
additional area introduced for some of the same region on Day
5/Thursday. Depending on the evolution of the upper-level troughs
that continue to progress across the northern CONUS, fire weather
concerns could persist into Day 6/Friday. However, forecast
certainty remains too low to introduce additional probabilities at
this time.

..Stearns.. 08/30/2026

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