Alert archive / Minnesota / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 93, NWS Grand Forks, ND

August 9, 20214 counties in Minnesota

NWS Grand Forks, ND issued this severe thunderstorm warning at Aug 9, 2021, 11:29 PM CDT for 4 counties in Minnesota. It was in force for 61 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 9, 2021, 11:29 PM CDT (04:29 UTC)
Expired: Aug 10, 2021, 12:30 AM CDT
In force: 61 min
Issued by: NWS Grand Forks, ND
Area: Storm-based polygon
Tornado: Possible
Damage threat: Considerable
Hail: 1.0 in
Wind: 70.0 mph

Counties Marshall County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN

The radar

The Fargo/Grand Forks radar (KMVX), 123 km from the middle of the area, began a volume at 04:31 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 9, 11:31 PM CDT	TSTM WND DMG	3 Nne Dorothy, MN	PICTURE RECEIVED OF DOWNED LARGE TREE, WITH REPORT OF ADDITIONAL TREES DAMAGE AROUND THE AREA. TIME ESTIMATED FROM RADAR. REPORT VIA SOCIAL MEDIA.
Aug 9, 11:31 PM CDT	TSTM WND DMG	3 Nne Dorothy, MN	PICTURE RECEIVED OF LARGE TREE DOWN, WITH REPORT OF ADDITIONAL TREES DAMAGE AROUND THE AREA. TIME ESTIMATED FROM RADAR. REPORT VIA SOCIAL MEDIA.
Aug 9, 11:31 PM CDT	TSTM WND DMG	3 Nne Dorothy, MN	SEVERAL LARGE TREES BLOWN DOWN, ALONG WITH NUMEROUS LARGE TREE BRANCHES AND LIMBS. REPORT AND PHOTOS POSTED VUA SOCIAL MEDIA. TIME ESTIMATED BASED ON RADAR.

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

The nearest sounding before it

International Fa, MN (KINL), launched 00:00Z, 4.5 hours before the alert went out and 205 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: 1281 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 1326 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 220 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted.

135 
WUUS53 KFGF 100429
SVRFGF
MNC089-113-119-125-100530-
/O.NEW.KFGF.SV.W.0093.210810T0429Z-210810T0530Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Grand Forks ND
1129 PM CDT Mon Aug 9 2021

The National Weather Service in Grand Forks has issued a

* Severe Thunderstorm Warning for...
  Eastern Marshall County in northwestern Minnesota...
  Red Lake County in northwestern Minnesota...
  Central Polk County in northwestern Minnesota...
  Pennington County in northwestern Minnesota...

* Until 1230 AM CDT.

* At 1129 PM CDT, severe thunderstorms were located along a line
  extending from near Old Mill State Park to 7 miles northwest of St.
  Hilaire to near Gentilly, moving northeast at 35 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Severe thunderstorms will be near...
  Carpenters Corner around 1130 PM CDT.
  St. Hilaire around 1135 PM CDT.
  Newfolden and Rosewood around 1140 PM CDT.
  Thief River Falls, Perault and Dakota Junction around 1145 PM CDT.

Other locations in the path of these severe thunderstorms include Red
Lake Falls.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4854 9565 4832 9560 4795 9559 4774 9652
      4799 9654 4841 9660
TIME...MOT...LOC 0429Z 241DEG 29KT 4834 9645 4807 9634 4777 9648 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

TG

3 follow-up statements

905 
WWUS53 KFGF 100448
SVSFGF

Severe Weather Statement
National Weather Service Grand Forks ND
1148 PM CDT Mon Aug 9 2021

MNC119-100457-
/O.CAN.KFGF.SV.W.0093.000000T0000Z-210810T0530Z/
Polk MN-
1148 PM CDT Mon Aug 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL POLK COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4854 9565 4832 9560 4795 9559 4786 9628
      4800 9634 4829 9639
TIME...MOT...LOC 0447Z 250DEG 29KT 4798 9619 

$$

MNC089-113-125-100530-
/O.CON.KFGF.SV.W.0093.000000T0000Z-210810T0530Z/
Marshall MN-Red Lake MN-Pennington MN-
1148 PM CDT Mon Aug 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM CDT
FOR EASTERN MARSHALL...NORTHEASTERN RED LAKE AND PENNINGTON
COUNTIES...

At 1147 PM CDT, a severe thunderstorm was located over St. Hilaire,
or 9 miles south of Thief River Falls, moving east at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
  Hazel, Plummer, Mavie, High Landing and Goodridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4854 9565 4832 9560 4795 9559 4786 9628
      4800 9634 4829 9639
TIME...MOT...LOC 0447Z 250DEG 29KT 4798 9619 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

TG

020 
WWUS53 KFGF 100509
SVSFGF

Severe Weather Statement
National Weather Service Grand Forks ND
1209 AM CDT Tue Aug 10 2021

MNC089-113-125-100530-
/O.CON.KFGF.SV.W.0093.000000T0000Z-210810T0530Z/
Marshall MN-Red Lake MN-Pennington MN-
1209 AM CDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM CDT
FOR EASTERN MARSHALL...NORTHEASTERN RED LAKE AND EASTERN PENNINGTON
COUNTIES...

At 1209 AM CDT, a severe thunderstorm was located over Goodridge, or
18 miles east of Thief River Falls, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Grygla, Goodridge, Gatzke, Mavie, High Landing, Espelie and Roland. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4854 9565 4832 9560 4795 9559 4790 9594
      4805 9598 4839 9610
TIME...MOT...LOC 0509Z 253DEG 36KT 4811 9578 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

TG

156 
WWUS53 KFGF 100528
SVSFGF

Severe Weather Statement
National Weather Service Grand Forks ND
1228 AM CDT Tue Aug 10 2021

MNC089-113-125-100538-
/O.EXP.KFGF.SV.W.0093.000000T0000Z-210810T0530Z/
Marshall MN-Red Lake MN-Pennington MN-
1228 AM CDT Tue Aug 10 2021

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN MARSHALL...
NORTHEASTERN RED LAKE AND EASTERN PENNINGTON COUNTIES WILL EXPIRE AT
1230 AM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

LAT...LON 4854 9565 4832 9560 4795 9559 4790 9594
      4805 9598 4839 9610
TIME...MOT...LOC 0528Z 241DEG 29KT 4817 9561 

$$

Riddle

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 9:54 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FGF	Polk	66 min
Aug 9, 10:42 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FGF	Norman, Pennington, Polk, Red Lake	63 min
Aug 9, 11:05 PM CDT	Tornado Warning	FGF	Polk	25 min
Aug 10, 2:20 AM CDT	Special Weather Statement	FGF	Lake of the Woods	25 min
Aug 10, 2:55 AM CDT	Special Weather Statement	FGF	Lake of the Woods	35 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 2021 Every severe thunderstorm warning 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.