Alert archive / North Dakota / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 282

May 21, 200734 counties in North Dakota

The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2007, 1:11 PM MDT for 34 counties in North Dakota. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued: May 21, 2007, 1:11 PM MDT (19:11 UTC)
Expired: May 21, 2007, 10:00 PM MDT
In force: 9 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2.5 in
Strongest gust expected: 60 kt

All 34 counties

Adams County, ND, Benson County, ND, Billings County, ND, Bottineau County, ND, Bowman County, ND, Burleigh County, ND, Cavalier County, ND, Dunn County, ND, Eddy County, ND, Emmons County, ND, Foster County, ND, Grant County, ND, Hettinger County, ND, Kidder County, ND, Logan County, ND, McHenry County, ND, McIntosh County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Mountrail County, ND, Oliver County, ND, Pierce County, ND, Ramsey County, ND, Renville County, ND, Rolette County, ND, Sheridan County, ND, Sioux County, ND, Slope County, ND, Stark County, ND, Stutsman County, ND, Towner County, ND, Ward County, ND, Wells County, ND

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: 5%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 80%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 95%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 21, 3:50 PM MDT	Severe Thunderstorm Warning	BIS	Ward	55 min
May 21, 4:42 PM MDT	Severe Thunderstorm Warning	BIS	Ward	63 min
May 21, 4:57 PM MDT	Tornado Warning	BIS	Ward	33 min
May 21, 4:58 PM MDT	Severe Thunderstorm Warning	BIS	Burleigh, Sheridan	62 min
May 21, 5:21 PM MDT	Severe Thunderstorm Warning	BIS	Mercer, Oliver	54 min
May 21, 5:25 PM MDT	Severe Thunderstorm Warning	BIS	Morton	65 min
May 21, 5:36 PM MDT	Severe Thunderstorm Warning	BIS	McHenry	54 min
May 21, 5:41 PM MDT	Severe Thunderstorm Warning	BIS	Bottineau	64 min
May 21, 5:46 PM MDT	Severe Thunderstorm Warning	BIS	Mountrail	59 min
May 21, 6:00 PM MDT	Severe Thunderstorm Warning	BIS	Sheridan	60 min
May 21, 6:05 PM MDT	Tornado Warning	BIS	Morton	25 min
May 21, 6:12 PM MDT	Severe Thunderstorm Warning	BIS	McHenry	47 min
May 21, 6:14 PM MDT	Severe Thunderstorm Warning	BIS	Mercer, Oliver	61 min
May 21, 6:17 PM MDT	Severe Thunderstorm Warning	BIS	Renville	28 min
May 21, 6:22 PM MDT	Tornado Warning	BIS	Oliver	38 min
May 21, 6:29 PM MDT	Tornado Warning	BIS	Morton	31 min
May 21, 6:35 PM MDT	Severe Thunderstorm Warning	BIS	Ward	55 min
May 21, 6:47 PM MDT	Severe Thunderstorm Warning	BIS	Pierce, Rolette	58 min
May 21, 6:50 PM MDT	Severe Thunderstorm Warning	BIS	Bottineau	25 min
May 21, 6:53 PM MDT	Severe Thunderstorm Warning	BIS	McLean	67 min
May 21, 7:00 PM MDT	Severe Thunderstorm Warning	BIS	Morton, Oliver	60 min
May 21, 7:08 PM MDT	Severe Thunderstorm Warning	BIS	Pierce, Rolette	67 min
May 21, 7:17 PM MDT	Severe Thunderstorm Warning	BIS	Mercer	25 min
May 21, 7:25 PM MDT	Severe Thunderstorm Warning	BIS	Ward	38 min
May 21, 7:40 PM MDT	Severe Thunderstorm Warning	FGF	Benson, Towner	65 min
May 21, 7:58 PM MDT	Severe Thunderstorm Warning	BIS	Burleigh, McLean, Morton, Oliver, Sheridan	62 min
May 21, 8:49 PM MDT	Severe Thunderstorm Warning	FGF	Benson	56 min
May 21, 9:00 PM MDT	Severe Thunderstorm Warning	BIS	Burleigh	50 min
May 21, 9:16 PM MDT	Severe Thunderstorm Warning	FGF	Cavalier	59 min
May 21, 9:45 PM MDT	Severe Thunderstorm Warning	FGF	Towner	33 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, 7.2 hours before the alert went out and 118 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: 124 J/kg
Mixed-layer CIN: -413 J/kg
Mixed-layer LCL: 1282 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 231 m²/s²
0-3 km storm-relative helicity: 150 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 2:59 AM MDT	Mesoscale Discussion	SPC	Barnes, Benson, Bottineau, Burke, Cass, Cavalier and 20 more	91 min
May 21, 12:22 PM MDT	Mesoscale Discussion	SPC	Adams, Benson, Bottineau, Bowman, Burleigh, Dunn and 20 more	83 min
May 21, 5:17 PM MDT	Mesoscale Discussion	SPC	Adams, Benson, Bottineau, Burleigh, Dunn, Emmons and 18 more	88 min

Nearby

Severe Thunderstorm Watches in North Dakota, 2007 Every severe thunderstorm watch in 2007

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.