Severe Thunderstorm Warning 170, NWS Grand Forks, ND

Area Forecast Discussion
National Weather Service Grand Forks ND
721 PM CDT Mon Aug 18 2025

.KEY MESSAGES...

- Scattered thunderstorms this afternoon evening in southeast
  North Dakota and then patchy fog tonight for all areas.

- Strong to severe thunderstorms are possible Thursday with
  strong winds and large hail as the primary threats.

&&

.UPDATE...
Issued at 648 PM CDT Mon Aug 18 2025

Cluster of thunderstorms have recently developed near the upper
James and Sheyenne River Valleys. While there is strong
instability to feed storms, wind shear is greatly lacking. This
will promote outflow boundary to propagate away from storms.
With instability gradient to the southeast as well as upper flow
to the east, expecting storms to migrate generally east through
the remainder afternoon into early evening.

Storms have exhibited gusty winds as high as 60 mph, and will
be capable of doing so given wet microburst-type potential
reinforcing the outflow boundary. The chance for other hazards
like large hail and tornado is very low, although cannot be
ruled out should outflow and/or storm interactions occur from
newly developed storms not undercut by outflow boundaries.

&&

.DISCUSSION...
Issued at 229 PM CDT Mon Aug 18 2025

...Synopsis...

As can be seen in current regional satellite imagery lead shortwave
activity across the upper great lakes continues to bring heavy rain
to areas of IA/MN/WI this morning with the SW monsoon ongoing in
areas of AZ/NM beneath building western ridging. In between closer
to home we have present southwest flow aloft with a transition to
more zonal flow today. Hurricane Erin can also be noted to the east
of the Bahamas. As this is influenced by the subtropical Bermuda high
the current midwest shortwave activity will aid digging eastern
troughing in pulling the storm north while upper diffluence stalls
mid level flow leading to slowing in the CONUS wide flow with riding
in the central and western US dominating Tuesday and Wednesday
before giving way to progressive troughing in the northern plains
Thursday and Friday with northwest flow across the upper Great Lakes
then prevailing through the weekend leading to overall cooler
temperatures in the 60s and 70s for highs Friday and beyond.

Today/tonight...

Lingering drizzle from this morning has subsided with the stratus
making a good effort to clear once it hit 11am. Overnight
thunderstorms to the east of Bismarck have dissipated but and
evident circulation in visible imagery with 2000 MUCAPE and maybe 20-
25kts of eff shear could serve as the focus point for afternoon
initiation. As the low tracks east though the afternoon along the
leading edge of an evident shortwave some strong but likely still
sub severe storms are possible in far southeast North Dakota between
5 and 8pm. MLCAPE around 2000-2500j/kg and up to 25kts of eff shear
will support a primary convective threat of lightning in addition to
some small hail and wind gusts up to 45 mph. Beyond possible storms
tonight fog once again appears likely though coverage will depend on
just how much low level saturation can be achieved though based on
water vapor across western and central North Dakota there appears to
be no lack of moisture to work with. Capped coverage at patchy
wording but would be entirely unsurprised to see a dense fog
advisory issued both tonight and Tuesday night given a once again
similar setup.

Aside from fog chances each relatively  weather Now through the
mid week. With ridging dominating through this time we will see
seasonable temperatures of highs in the low to mid 80s through
Thursday though dewpoints in the upper 60s to low 70s likely
aided by late August evapotranspiration will make for a humid
few days.

Severe Weather Thursday?...

By Thursday afternoon progressive troughing will swing through the
Canadian Prairies with an attendant cold front draped south
across the Dakotas and Minnesota by the evening/overnight. Will
the true degree of any severe threat would be contingent upon
the timing of the this front for the primary source of forcing
as it moves through an untapped warm sector already in place
with ensembles and even longer range CAMS such as the NAM
showing 2000-3000j/kg of MLCAPE ahead of the cold front with
enough shear to support organized convection. Would currently
anticipate a more linear mode given the forcing but would still
think to maintain at least some hail risk initially should
there be a window for more discrete convection. Beyond this main
window for potentially severe storms on Thursday General
thunderstorm activity remains possible both Tuesday and
Wednesday with more quiet northwest flow behind Thursday front
through the weekend as temps drop into the 60s for highs (almost
fall like).

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 648 PM CDT Mon Aug 18 2025

Scattered thunderstorms are moving through southeast ND into
west-central MN this afternoon into early evening. This will
impact KFAR between 01-03Z. Storms will be capable of gusty
winds to 25kt in addition to lightning.

After 04Z, low stratus and fog are forecast to develop across
the region. Confidence is high enough to include these
scenarios, however, it remains unclear how thick fog will be at
each site. KBJI holds relatively highest chance for seeing dense
fog/LIFR conditions between 10-15Z.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

UPDATE...CJ
DISCUSSION...TT
AVIATION...CJ

Hazardous Weather Outlook
National Weather Service Grand Forks ND
244 PM CDT Mon Aug 18 2025

NDZ006-007-014-015-191945-
Towner-Cavalier-Benson-Ramsey-
244 PM CDT Mon Aug 18 2025

This hazardous weather outlook is for portions of eastern North
Dakota.

.DAY ONE...This Afternoon and Tonight

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

There is a level 1 out of 5 risk for severe thunderstorms
Wednesday. The main hazards will be large hail and strong winds.
There is another chance for strong to severe storms on Thursday as
well.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today.

MNZ001>009-013>017-022>024-027>032-040-NDZ008-016-024-026>030-038-
039-049-052>054-191945-
West Polk-Norman-Clay-Kittson-Roseau-Lake Of The Woods-
West Marshall-East Marshall-North Beltrami-Pennington-Red Lake-
East Polk-North Clearwater-South Beltrami-Mahnomen-
South Clearwater-Hubbard-West Becker-East Becker-Wilkin-
West Otter Tail-East Otter Tail-Wadena-Grant-Pembina-
Eastern Walsh-Eddy-Nelson-Grand Forks-Griggs-Steele-Traill-Barnes-
Cass-Ransom-Sargent-Richland-Western Walsh-
244 PM CDT Mon Aug 18 2025

This hazardous weather outlook is for portions of eastern North
Dakota, west central and northwest Minnesota.

.DAY ONE...This Afternoon and Tonight

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

There is a chance for strong to severe storms on Thursday. The
main hazards will be large hail and strong winds.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today.

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Special Weather Statement
National Weather Service Grand Forks ND
707 PM CDT Mon Aug 18 2025

NDZ029-030-039-190030-
Steele ND-Traill ND-Cass ND-
707 PM CDT Mon Aug 18 2025

...STRONG THUNDERSTORMS WILL IMPACT CASS...SOUTHERN TRAILL AND
SOUTHEASTERN STEELE COUNTIES THROUGH 730 PM CDT...

At 707 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Portland to near Arthur to Enderlin.
Movement was east at 25 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Western Fargo, West Fargo, Horace, Casselton, Hillsboro, Mapleton,
and Harwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4663 9768 4678 9768 4720 9754 4746 9753
      4752 9686 4742 9687 4741 9685 4737 9686
      4733 9683 4720 9684 4719 9684 4718 9682
      4716 9682 4715 9684 4711 9682 4704 9682
      4704 9681 4701 9684 4696 9681 4663 9690
TIME...MOT...LOC 0007Z 287DEG 22KT 4752 9742 4714 9714 4664 9759

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Perroux

Special Weather Statement
National Weather Service Grand Forks ND
718 PM CDT Mon Aug 18 2025

NDZ038-049-190045-
Ransom ND-Barnes ND-
718 PM CDT Mon Aug 18 2025

...STRONG THUNDERSTORMS WILL IMPACT  THROUGH 745 PM CDT...

At 718 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles northwest of Hastings to near Marion.
Movement was southeast at 40 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Litchville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4663 9843 4674 9844 4663 9803
TIME...MOT...LOC 0018Z 293DEG 36KT 4677 9818 4659 9826

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Perroux

Special Weather Statement
National Weather Service Grand Forks ND
726 PM CDT Mon Aug 18 2025

NDZ029-030-190100-
Steele ND-Traill ND-
726 PM CDT Mon Aug 18 2025

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN TRAILL AND NORTHEASTERN
STEELE COUNTIES THROUGH 800 PM CDT...

At 726 PM CDT, Doppler radar was tracking a strong thunderstorm near
Portland, or 30 miles southwest of Grand Forks, moving southeast at 5
mph.

HAZARD...Wind gusts of 50 to 55 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Mayville, Hatton, Portland, Cummings, and Roseville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4767 9750 4767 9745 4756 9695 4738 9751
      4762 9762
TIME...MOT...LOC 0026Z 331DEG 4KT 4755 9745

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH

Perroux

Special Weather Statement
National Weather Service Grand Forks ND
728 PM CDT Mon Aug 18 2025

MNZ002-003-NDZ030-039-049-053-190130-
Clay MN-Norman MN-Ransom ND-Traill ND-Richland ND-Cass ND-
728 PM CDT Mon Aug 18 2025

...STRONG THUNDERSTORMS WILL IMPACT CLAY...WESTERN NORMAN...
NORTHEASTERN RANSOM...CASS...SOUTHERN TRAILL AND NORTHWESTERN
RICHLAND COUNTIES THROUGH 830 PM CDT...

At 728 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Hillsboro to Harwood to Anselm. Movement
was east at 40 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Fargo, Moorhead, West Fargo, Dilworth, Horace, Casselton, and Hawley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4656 9769 4704 9742 4740 9747 4757 9693
      4753 9686 4750 9685 4750 9679 4733 9644
      4682 9628 4663 9664 4663 9678 4657 9675
      4637 9711
TIME...MOT...LOC 0028Z 291DEG 35KT 4745 9713 4699 9688 4654 9747

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Perroux