Alert archive / North Dakota / Tornado Warnings in 2021

Tornado Warning 10, NWS Grand Forks, ND

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

NWS Grand Forks, ND issued this tornado warning at Aug 20, 2021, 4:13 PM CDT for Cass County, Traill County, North Dakota. It was in force for 47 min. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 20, 2021, 4:13 PM CDT (21:13 UTC)
Expired: Aug 20, 2021, 5:00 PM CDT
In force: 47 min
Issued by: NWS Grand Forks, ND
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Cass County, ND, Traill County, ND

The radar

The Fargo/Grand Forks radar (KMVX), 38 km from the middle of the area, began a volume at 21:17 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.

What was reported inside it

Time	Report	Where	Remark
Aug 20, 4:18 PM CDT	TORNADO 0	4 E Erie, ND	A FUNNEL WITH BRIEF TOUCHDOWN. REPORT POSTED VIA SOCIAL MEDIA. SOME TREE BRANCHES AND CORN STALKS WERE SEEN SWIRLING IN THE DEBRIS. PEAK WINDS ESTIMATED TO 70 MPH. MAXIMUM WIDTH TO 40 YARDS. TRACK LENGTH OF LESS THAN ONE HALF MILE TO THE EAST-NORTHEAST BY 419
Aug 20, 4:18 PM CDT	TORNADO 0	4 E Erie, ND	A FUNNEL WITH BRIEF TOUCHDOWN. REPORT POSTED VIA SOCIAL MEDIA. SOME TREE BRANCHES AND CORN STALKS WERE SEEN SWIRLING IN THE DEBRIS. PEAK WINDS ESTIMATED TO 70 MPH. MAXIMUM WIDTH TO 40 YARDS. TRACK LENGTH OF LESS THAN ONE QUARTER MILE TO THE EAST-NORTHEAST BY 4
Aug 20, 4:18 PM CDT	TORNADO	4 E Erie, ND	A FUNNEL WITH BRIEF TOUCHDOWN. REPORT POSTED VIA SOCIAL MEDIA.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

Issued	Product	Office	Lasted
Aug 20, 2:24 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 12:00Z, 9.2 hours before the alert went out and 266 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 306 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 609 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 163 m²/s²
0-3 km storm-relative helicity: 141 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

448 
WFUS53 KFGF 202113
TORFGF
NDC017-097-202200-
/O.NEW.KFGF.TO.W.0010.210820T2113Z-210820T2200Z/

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

The National Weather Service in Grand Forks has issued a

* Tornado Warning for...
  North central Cass County in southeastern North Dakota...
  Southeastern Traill County in southeastern North Dakota...

* Until 500 PM CDT.
    
* At 413 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Erie, or 28 miles northwest of Fargo, 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...
  Arthur around 425 PM CDT.

Other locations in the path of this tornadic thunderstorm include
Hunter, Kelso, Blanchard and Grandin.

This includes Interstate 29 between mile markers 91 and 101.
 
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 4708 9741 4745 9728 4730 9689 4702 9727
TIME...MOT...LOC 2113Z 211DEG 20KT 4708 9733 

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

$$

CJ

2 follow-up statements

335 
WWUS53 KFGF 202139
SVSFGF

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

NDC017-097-202200-
/O.CON.KFGF.TO.W.0010.000000T0000Z-210820T2200Z/
Cass ND-Traill ND-
439 PM CDT Fri Aug 20 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CDT FOR NORTH
CENTRAL CASS AND SOUTHEASTERN TRAILL COUNTIES...
    
At 439 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Hunter, or 29 miles northwest of Fargo, 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.

Locations impacted include...
  Blanchard, Grandin and Kelso.

This includes Interstate 29 between mile markers 91 and 101.
 
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 4745 9728 4730 9689 4720 9703 4719 9737
TIME...MOT...LOC 2139Z 211DEG 20KT 4721 9722 

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

$$

CJ

627 
WWUS53 KFGF 202153
SVSFGF

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

NDC017-097-202202-
/O.EXP.KFGF.TO.W.0010.000000T0000Z-210820T2200Z/
Cass ND-Traill ND-
453 PM CDT Fri Aug 20 2021

...THE TORNADO WARNING FOR NORTH CENTRAL CASS AND SOUTHEASTERN TRAILL
COUNTIES WILL EXPIRE AT 500 PM CDT...
    
The tornado threat has diminished and the Tornado Warning has been 
cancelled. However, damaging winds remain likely and a Severe 
Thunderstorm Warning remains in effect for the area. 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 4745 9728 4730 9689 4720 9703 4719 9737
TIME...MOT...LOC 2152Z 211DEG 20KT 4726 9717 

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 9:47 AM CDT	Special Weather Statement	FGF	Grand Forks	28 min
Aug 20, 11:04 AM CDT	Areal Flood Advisory	FGF	Grand Forks	4 hr
Aug 20, 11:12 AM CDT	Special Weather Statement	FGF	Cass	33 min
Aug 20, 2:43 PM CDT	Tornado Warning	FGF	Barnes, Cass	47 min
Aug 20, 3:24 PM CDT	Special Weather Statement	FGF	Cass	36 min
Aug 20, 3:49 PM CDT	Special Weather Statement	FGF	Griggs	56 min
Aug 20, 4:00 PM CDT	Special Weather Statement	FGF	Traill	60 min
Aug 20, 4:11 PM CDT	Tornado Warning	FGF	Barnes, Griggs, Steele	49 min
Aug 20, 4:49 PM CDT	Severe Thunderstorm Warning	FGF	Traill	26 min
Aug 20, 4:51 PM CDT	Special Weather Statement	FGF	Steele	54 min
Aug 20, 5:11 PM CDT	Special Weather Statement	FGF	Ramsey	49 min
Aug 20, 5:13 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FGF	Grand Forks, Traill	39 min
Aug 20, 6:24 PM CDT	Special Weather Statement	FGF	Walsh	51 min

Nearby

Tornado Warnings in North Dakota, 2021 Every tornado warning in 2021 Tornadoes 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.