Alert archive / North Dakota / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 428

July 21, 201720 counties in Minnesota; 29 counties in North Dakota; 17 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2017, 3:07 PM CDT for 20 counties in Minnesota; 29 counties in North Dakota; 17 counties in South Dakota. It was in force for 10 hr.

The area

The outline as issued.

The facts

Issued: Jul 21, 2017, 3:07 PM CDT (20:07 UTC)
Expired: Jul 22, 2017, 1:00 AM CDT
In force: 10 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 66 counties

Aitkin County, MN, Becker County, MN, Beltrami County, MN, Carlton County, MN, Cass County, MN, Clay County, MN, Clearwater County, MN, Crow Wing County, MN, Grant County, MN, Hubbard County, MN, Mahnomen County, MN, Norman County, MN, Otter Tail County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN, Saint Louis County, MN, Traverse County, MN, Wadena County, MN, Wilkin County, MN, Barnes County, ND, Bottineau County, ND, Burleigh County, ND, Cass County, ND, Dickey County, ND, Eddy County, ND, Emmons County, ND, Foster County, ND, Grand Forks County, ND, Grant County, ND, Griggs County, ND, Kidder County, ND, LaMoure County, ND, Logan County, ND, McHenry County, ND, McIntosh County, ND, Morton County, ND, Nelson County, ND, Pierce County, ND, Ransom County, ND, Richland County, ND, Rolette County, ND, Sargent County, ND, Sheridan County, ND, Sioux County, ND, Steele County, ND, Stutsman County, ND, Traill County, ND, Wells County, ND, Brown County, SD, Campbell County, SD, Corson County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Marshall County, SD, McPherson County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Sully County, SD, Walworth County, SD

The radar

The Fargo/Grand Forks radar (KMVX), 127 km from the middle of the area, began a volume at 20:09 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 20%
One or more EF2 to EF5 tornadoes: 10%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 60%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

68 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 21, 3:24 PM CDT	Severe Thunderstorm Warning	FGF	Barnes, Eddy, Griggs, Steele	66 min
Jul 21, 3:37 PM CDT	Severe Thunderstorm Warning	FGF	Beltrami	23 min
Jul 21, 4:10 PM CDT	Severe Thunderstorm Warning	FGF	Norman, Polk	65 min
Jul 21, 4:15 PM CDT	Severe Thunderstorm Warning	FGF	Beltrami, Clearwater, Polk, Red Lake	60 min
Jul 21, 4:51 PM CDT	Severe Thunderstorm Warning	FGF	Becker, Beltrami, Clearwater, Hubbard, Mahnomen, Polk	54 min
Jul 21, 4:51 PM CDT	Severe Thunderstorm Warning	FGF	Clay	54 min
Jul 21, 5:24 PM CDT	Severe Thunderstorm Warning	DLH	Cass	36 min
Jul 21, 5:29 PM CDT	Severe Thunderstorm Warning	FGF	Becker, Clearwater, Mahnomen	61 min
Jul 21, 5:44 PM CDT	Severe Thunderstorm Warning	FGF	Beltrami, Clearwater, Hubbard	35 min
Jul 21, 5:48 PM CDT	Severe Thunderstorm Warning	DLH	Cass, Itasca	12 min
Jul 21, 5:49 PM CDT	Severe Thunderstorm Warning	FGF	Becker, Clay, Otter Tail, Wilkin	56 min
Jul 21, 5:59 PM CDT	Severe Thunderstorm Warning	DLH	Cass, Itasca	46 min
Jul 21, 6:01 PM CDT	Severe Thunderstorm Warning	FGF	Richland	35 min
Jul 21, 6:16 PM CDT	Severe Thunderstorm Warning	ABR	Roberts	44 min
Jul 21, 6:21 PM CDT	Severe Thunderstorm Warning	DLH	Aitkin, Cass, Crow Wing, Itasca	39 min
Jul 21, 6:28 PM CDT	Severe Thunderstorm Warning	FGF	Becker	31 min
Jul 21, 6:34 PM CDT	Severe Thunderstorm Warning	DLH	Saint Louis	26 min
Jul 21, 6:43 PM CDT	Severe Thunderstorm Warning	BIS	Grant, Sioux	62 min
Jul 21, 6:48 PM CDT	Severe Thunderstorm Warning	DLH	Cass, Itasca	11 min
Jul 21, 6:50 PM CDT	Severe Thunderstorm Warning	DLH	Cass, Crow Wing	40 min
Jul 21, 6:53 PM CDT	Severe Thunderstorm Warning	DLH	Aitkin, Cass, Crow Wing, Itasca	37 min
Jul 21, 6:56 PM CDT	Severe Thunderstorm Warning	ABR	Traverse	51 min
Jul 21, 6:57 PM CDT	Severe Thunderstorm Warning	FGF	Otter Tail, Wilkin	63 min
Jul 21, 6:59 PM CDT	Severe Thunderstorm Warning	DLH	Saint Louis	46 min
Jul 21, 7:09 PM CDT	Severe Thunderstorm Warning	DLH	Aitkin, Carlton, Crow Wing	51 min
Jul 21, 7:14 PM CDT	Severe Thunderstorm Warning	DLH	Aitkin, Carlton, Itasca, Saint Louis	46 min
Jul 21, 7:18 PM CDT	Severe Thunderstorm Warning	BIS	Bottineau, Burke, Renville	57 min
Jul 21, 7:19 PM CDT	Severe Thunderstorm Warning	BIS	Emmons, Logan, McIntosh	56 min
Jul 21, 7:31 PM CDT	Severe Thunderstorm Warning	ABR	Corson	44 min
Jul 21, 7:37 PM CDT	Flash Flood Warning	DLH	Carlton, Saint Louis	6 hr
Jul 21, 7:49 PM CDT	Severe Thunderstorm Warning	DLH	Aitkin, Carlton, Pine	41 min
Jul 21, 7:49 PM CDT	Severe Thunderstorm Warning	ABR	Edmunds	41 min
Jul 21, 7:59 PM CDT	Severe Thunderstorm Warning	DLH	Carlton, Saint Louis	46 min
Jul 21, 8:09 PM CDT	Severe Thunderstorm Warning	ABR	Faulk, Hyde, Potter, Sully	51 min
Jul 21, 8:10 PM CDT	Severe Thunderstorm Warning	BIS	LaMoure, Logan, Stutsman	65 min
Jul 21, 8:10 PM CDT	Severe Thunderstorm Warning	BIS	McHenry, McLean, Sheridan, Ward	65 min
Jul 21, 8:14 PM CDT	Severe Thunderstorm Warning	BIS	Bottineau, Renville	61 min
Jul 21, 8:14 PM CDT	Severe Thunderstorm Warning	ABR	Edmunds, McPherson	28 min
Jul 21, 8:16 PM CDT	Severe Thunderstorm Warning	BIS	Burleigh, McLean, Oliver	59 min
Jul 21, 8:25 PM CDT	Severe Thunderstorm Warning	ABR	Edmunds, Faulk	50 min
Jul 21, 8:29 PM CDT	Severe Thunderstorm Warning	DLH	Carlton, Pine	33 min
Jul 21, 8:48 PM CDT	Tornado Warning	BIS	Burleigh, Oliver	27 min
Jul 21, 8:52 PM CDT	Severe Thunderstorm Warning	ABR	Faulk, Hand	38 min
Jul 21, 9:09 PM CDT	Severe Thunderstorm Warning	BIS	Bottineau, McHenry, Pierce, Rolette	66 min
Jul 21, 9:13 PM CDT	Severe Thunderstorm Warning	BIS	Burleigh	62 min
Jul 21, 9:21 PM CDT	Severe Thunderstorm Warning	ABR	Edmunds, Walworth	11 min
Jul 21, 9:40 PM CDT	Severe Thunderstorm Warning	BIS	McHenry, Pierce, Ward	65 min
Jul 21, 9:44 PM CDT	Severe Thunderstorm Warning	BIS	Dickey, LaMoure	61 min
Jul 21, 9:47 PM CDT	Severe Thunderstorm Warning	BIS	Burleigh, Morton, Oliver	58 min
Jul 21, 9:48 PM CDT	Severe Thunderstorm Warning	ABR	Faulk, Hand, Spink	42 min
Jul 21, 9:58 PM CDT	Severe Thunderstorm Warning	ABR	Potter	18 min
Jul 21, 10:12 PM CDT	Severe Thunderstorm Warning	BIS	McHenry, Pierce	33 min
Jul 21, 10:16 PM CDT	Tornado Warning	BIS	Pierce	29 min
Jul 21, 10:21 PM CDT	Severe Thunderstorm Warning	ABR	Faulk, Hand, Spink	39 min
Jul 21, 10:24 PM CDT	Severe Thunderstorm Warning	BIS	Burleigh, Morton	66 min
Jul 21, 10:27 PM CDT	Severe Thunderstorm Warning	ABR	Hand, Spink	48 min
Jul 21, 10:42 PM CDT	Severe Thunderstorm Warning	ABR	Spink	48 min
Jul 21, 10:44 PM CDT	Severe Thunderstorm Warning	ABR	Brown, Spink	46 min
Jul 21, 10:51 PM CDT	Severe Thunderstorm Warning	BIS	Pierce	54 min
Jul 21, 10:52 PM CDT	Severe Thunderstorm Warning	BIS	Burleigh, Emmons, Morton	68 min
Jul 21, 11:00 PM CDT	Severe Thunderstorm Warning	BIS	LaMoure	15 min
Jul 21, 11:11 PM CDT	Severe Thunderstorm Warning	ABR	Clark, Spink	64 min
Jul 21, 11:13 PM CDT	Severe Thunderstorm Warning	ABR	Hand, Spink	32 min
Jul 21, 11:18 PM CDT	Severe Thunderstorm Warning	ABR	Hand, Hyde	42 min
Jul 21, 11:27 PM CDT	Severe Thunderstorm Warning	ABR	Clark, Codington, Day, Hamlin, Spink	63 min
Jul 21, 11:41 PM CDT	Severe Thunderstorm Warning	BIS	Logan, McIntosh	64 min
Jul 21, 11:47 PM CDT	Severe Thunderstorm Warning	ABR	Buffalo, Hand, Hyde	28 min
Jul 22, 12:25 AM CDT	Severe Thunderstorm Warning	FGF	Eddy	27 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 12:00Z, 8.1 hours before the alert went out and 162 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: 211 J/kg
Mixed-layer CIN: -475 J/kg
Mixed-layer LCL: 1536 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 85 m²/s²
0-3 km storm-relative helicity: 238 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 9:42 AM CDT	Mesoscale Discussion	SPC	Kittson, Marshall	93 min
Jul 21, 12:47 PM CDT	Mesoscale Discussion	SPC	Clearwater, Kittson, Mahnomen, Marshall, Norman, Pennington and 2 more	88 min
Jul 21, 2:20 PM CDT	Mesoscale Discussion	SPC	Becker, Beltrami, Clay, Clearwater, Hubbard, Mahnomen and 7 more	2 hr
Jul 21, 3:53 PM CDT	Mesoscale Discussion	SPC	Becker, Beltrami, Clay, Clearwater, Mahnomen, Norman and 4 more	97 min
Jul 21, 6:25 PM CDT	Mesoscale Discussion	SPC	Aitkin, Becker, Benton, Big Stone, Carlton, Cass and 16 more	95 min
Jul 20, 7:31 PM CDT	Mesoscale Discussion	SPC	Emmons, Grant, Morton, Sioux	89 min
Jul 20, 10:26 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Campbell, Edmunds, Faulk, Hand, Hyde and 5 more	3 hr
Jul 20, 11:25 PM CDT	Mesoscale Discussion	SPC	Brown, Campbell, Edmunds, Faulk, McPherson, Potter and 3 more	65 min

Nearby

Severe Thunderstorm Watches in North Dakota, 2017 Severe Thunderstorm Watches in Minnesota, 2017 Severe Thunderstorm Watches in South Dakota, 2017 Every severe thunderstorm watch in 2017

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.