Alert archive / North Dakota / Tornado Watches in 2011

Tornado Watch 674

July 22, 2011Big Stone County, Traverse County, Wilkin County, Minnesota; 5 counties in North Dakota; 5 counties in South Dakota

The Storm Prediction Center issued this tornado watch at Jul 22, 2011, 6:14 PM CDT for Big Stone County, Traverse County, Wilkin County, Minnesota; 5 counties in North Dakota; 5 counties in South Dakota. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: Jul 22, 2011, 6:14 PM CDT (23:14 UTC)
Expired: Jul 23, 2011, 1:56 AM CDT
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

Counties Big Stone County, MN, Traverse County, MN, Wilkin County, MN, Dickey County, ND, LaMoure County, ND, Ransom County, ND, Richland County, ND, Sargent County, ND, Brown County, SD, Day County, SD, Grant County, SD, Marshall County, SD, Roberts County, SD

The radar

The Aberdeen radar (KABR), 68 km from the middle of the area, began a volume at 23:16 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: 30%
One or more EF2 to EF5 tornadoes: 10%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 22, 6:43 PM CDT	Flash Flood Warning	ABR	Codington, Grant	6 hr
Jul 22, 7:35 PM CDT	Severe Thunderstorm Warning	ABR	Codington, Deuel, Grant	40 min
Jul 23, 12:08 AM CDT	Severe Thunderstorm Warning	BIS	Dickey, Emmons, LaMoure, Logan, McIntosh, Sioux	52 min
Jul 23, 12:57 AM CDT	Severe Thunderstorm Warning	BIS	Dickey, Kidder, LaMoure, Logan, McIntosh	63 min
Jul 23, 1:06 AM CDT	Severe Thunderstorm Warning	ABR	Brown, Edmunds, Faulk, McPherson, Spink	54 min
Jul 23, 1:51 AM CDT	Severe Thunderstorm Warning	FGF	Ransom, Sargent	54 min
Jul 23, 1:55 AM CDT	Severe Thunderstorm Warning	BIS	Dickey, LaMoure	50 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

Aberdeen, SD (KABR), launched 12:00Z, 11.2 hours before the alert went out and 128 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: 593 J/kg
Mixed-layer CIN: -243 J/kg
Mixed-layer LCL: 2003 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 58 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

765 
WWUS20 KWNS 222315
SEL4  
SPC WW 222315
MNZ000-NDZ000-SDZ000-230700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 674
NWS STORM PREDICTION CENTER NORMAN OK
615 PM CDT FRI JUL 22 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       FAR WEST CENTRAL MINNESOTA
       SOUTHEAST NORTH DAKOTA
       NORTHEAST SOUTH DAKOTA

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 615 PM
UNTIL 200 AM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 100 MILES WEST NORTHWEST OF
ABERDEEN SOUTH DAKOTA TO 30 MILES NORTH NORTHEAST OF ORTONVILLE
MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 670...WW 671...WW
672...WW 673...

DISCUSSION...TSTMS FORMING ALONG W/E WARM FRONT IN NE SD MAY POSE A
THREAT FOR SVR WEATHER AS ACTIVITY BUILDS/MOVES GENERALLY NWD. 
OTHER STORMS...LIKELY SLIGHTLY ELEVATED...MAY FORM ALONG PARALLEL
BOUNDARY FARTHER N IN SE ND.  WHILE AREA SHEAR IS WEAKER THAN THAT
IN WRN ND/SD AREA...COMBINATION OF FAIRLY RICH LOW LVL MOISTURE WITH
LOW LVL VEERING WIND PROFILES /PER AREA VWPS/ SUGGESTS A CHANCE FOR
A TORNADO OR TWO...IN ADDITION TO LOCALLY DMGG WIND/HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 21020.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 22, 3:00 PM CDT	Mesoscale Discussion	SPC	Blue Earth, Brown, Carver, Chippewa, Cottonwood, Dakota and 32 more	90 min
Jul 22, 5:46 PM CDT	Mesoscale Discussion	SPC	Big Stone, Grant, Stevens, Traverse, Wilkin	89 min
Jul 22, 11:05 AM CDT	Mesoscale Discussion	SPC	Adams, Billings, Bowman, Dunn, Golden Valley, Grant and 8 more	55 min
Jul 22, 5:17 PM CDT	Mesoscale Discussion	SPC	Adams, Billings, Bowman, Dunn, Golden Valley, Grant and 8 more	88 min
Jul 22, 5:35 PM CDT	Tornado Watch	SPC	Adams, Billings, Bowman, Burke, Burleigh, Divide and 21 more	8 hr
Jul 21, 7:10 PM CDT	Mesoscale Discussion	SPC	Bennett, Jackson, Jones, Lyman, Mellette, Todd and 1 more	95 min
Jul 22, 6:22 PM CDT	Mesoscale Discussion	SPC	Brule, Buffalo, Gregory, Lyman, Mellette, Todd and 1 more	53 min

Nearby

Tornado Watches in North Dakota, 2011 Tornado Watches in South Dakota, 2011 Tornado Watches in Minnesota, 2011 Every tornado watch in 2011

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.