Alert archive / North Dakota / Tornado Warnings in 2021

Tornado Warning 8, NWS Grand Forks, ND

August 20, 2021Barnes County, Cass County, North Dakota

NWS Grand Forks, ND issued this tornado warning at Aug 20, 2021, 2:43 PM CDT for Barnes County, Cass County, North Dakota. It was in force for 47 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 20, 2021, 2:43 PM CDT (19:43 UTC)
Expired
Aug 20, 2021, 3:30 PM CDT
In force
47 min
Issued by
NWS Grand Forks, ND
Area
Storm-based polygon
Tornado
Radar indicated
Hail
0.75 in

Counties Barnes County, ND, Cass County, ND

The radar

The Fargo/Grand Forks radar (KMVX), 92 km from the middle of the area, began a volume at 19:45 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 20, 2:24 PM CDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 7.7 hours before the alert went out and 212 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 12:00Z on 2021-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1019 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Aberdeen, SD at 12:00Z on 2021-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 45 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1019 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
682 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
45 m²/s²
0-3 km storm-relative helicity
73 m²/s²
Significant tornado parameter
0.3
Supercell composite
2.2

Open this sounding in Storm Lab

The text

As transmitted.

464 
WFUS53 KFGF 201943
TORFGF
NDC003-017-202030-
/O.NEW.KFGF.TO.W.0008.210820T1943Z-210820T2030Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Grand Forks ND
243 PM CDT Fri Aug 20 2021

The National Weather Service in Grand Forks has issued a

* Tornado Warning for...
  Southwestern Cass County in southeastern North Dakota...
  Southeastern Barnes County in southeastern North Dakota...

* Until 330 PM CDT.
    
* At 243 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Lucca, or 21 miles southeast of Valley City,
  moving northeast at 25 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Lucca around 250 PM CDT.
  Fingal around 255 PM CDT.

Other locations in the path of this tornadic thunderstorm include
Alice, Tower City and Buffalo.

This includes Interstate 94 in North Dakota between mile markers 303
and 327.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4665 9786 4700 9778 4688 9729 4663 9767
      4663 9776
TIME...MOT...LOC 1943Z 210DEG 21KT 4668 9774 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

CJ
2 follow-up statements
878 
WWUS53 KFGF 202010
SVSFGF

Severe Weather Statement
National Weather Service Grand Forks ND
310 PM CDT Fri Aug 20 2021

NDC003-202018-
/O.CAN.KFGF.TO.W.0008.000000T0000Z-210820T2030Z/
Barnes ND-
310 PM CDT Fri Aug 20 2021

...THE TORNADO WARNING FOR SOUTHEASTERN BARNES COUNTY IS CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
southeastern North Dakota.

LAT...LON 4677 9768 4698 9768 4688 9729 4667 9760
TIME...MOT...LOC 2008Z 210DEG 21KT 4681 9763 

$$

NDC017-202030-
/O.CON.KFGF.TO.W.0008.000000T0000Z-210820T2030Z/
Cass ND-
310 PM CDT Fri Aug 20 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 330 PM CDT FOR
SOUTHWESTERN CASS COUNTY...
    
At 308 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Alice, or 19 miles southeast of Valley City, moving
northeast at 25 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation. At 2:34 PM CDT, numerous reports 
         of a rotating wall cloud have been reported near Enderlin 
         to near Alice.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
  Tower City and Buffalo.

This includes Interstate 94 in North Dakota between mile markers 308
and 327.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4677 9768 4698 9768 4688 9729 4667 9760
TIME...MOT...LOC 2008Z 210DEG 21KT 4681 9763 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

CJ
660 
WWUS53 KFGF 202025
SVSFGF

Severe Weather Statement
National Weather Service Grand Forks ND
325 PM CDT Fri Aug 20 2021

NDC017-202035-
/O.EXP.KFGF.TO.W.0008.000000T0000Z-210820T2030Z/
Cass ND-
325 PM CDT Fri Aug 20 2021

...THE TORNADO WARNING FOR SOUTHWESTERN CASS COUNTY WILL EXPIRE AT
330 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning will be allowed to expire.  However gusty
winds are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
southeastern North Dakota.

LAT...LON 4677 9768 4698 9768 4688 9729 4667 9760
TIME...MOT...LOC 2025Z 210DEG 21KT 4689 9756 

$$

CJ

The office that day

Everything else NWS Grand Forks, ND issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 20, 9:47 AM CDTSpecial Weather StatementFGFGrand Forks28 min
Aug 20, 11:04 AM CDTAreal Flood AdvisoryFGFGrand Forks4 hr
Aug 20, 11:12 AM CDTSpecial Weather StatementFGFCass33 min
Aug 20, 3:24 PM CDTSpecial Weather StatementFGFCass36 min
Aug 20, 3:49 PM CDTSpecial Weather StatementFGFGriggs56 min
Aug 20, 4:00 PM CDTSpecial Weather StatementFGFTraill60 min
Aug 20, 4:11 PM CDTTornado WarningFGFBarnes, Griggs, Steele49 min
Aug 20, 4:13 PM CDTTornado WarningFGFCass, Traill47 min
Aug 20, 4:49 PM CDTSevere Thunderstorm WarningFGFTraill26 min
Aug 20, 4:51 PM CDTSpecial Weather StatementFGFSteele54 min
Aug 20, 5:11 PM CDTSpecial Weather StatementFGFRamsey49 min
Aug 20, 5:13 PM CDTSevere Thunderstorm Warning Considerable damage threatFGFGrand Forks, Traill39 min
Aug 20, 6:24 PM CDTSpecial Weather StatementFGFWalsh51 min

Nearby

Tornado Warnings in North Dakota, 2021Every tornado warning in 2021Tornadoes in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.