Alert archive / Minnesota / Tornado Watches in 2001

Tornado Watch 646

July 31, 200117 counties in Minnesota; 16 counties in North Dakota

The Storm Prediction Center issued this tornado watch at Jul 31, 2001, 4:00 PM CDT for 17 counties in Minnesota; 16 counties in North Dakota. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 31, 2001, 4:00 PM CDT (21:00 UTC)
Expired: Jul 31, 2001, 10:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 33 counties

Becker County, MN, Beltrami County, MN, Cass County, MN, Clay County, MN, Clearwater County, MN, Hubbard County, MN, Itasca County, MN, Kittson County, MN, Koochiching County, MN, Lake of the Woods County, MN, Mahnomen County, MN, Marshall County, MN, Norman County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN, Roseau County, MN, Barnes County, ND, Cass County, ND, Dickey County, ND, Eddy County, ND, Foster County, ND, Grand Forks County, ND, Griggs County, ND, LaMoure County, ND, Nelson County, ND, Pembina County, ND, Ramsey County, ND, Ransom County, ND, Steele County, ND, Stutsman County, ND, Traill County, ND, Walsh County, ND

The radar

The Fargo/Grand Forks radar (KMVX), 66 km from the middle of the area, began a volume at 21:00 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 31, 4:35 PM CDT	Flash Flood Warning	FGF	Marshall	6 hr
Jul 31, 4:39 PM CDT	Flash Flood Warning	FGF	Polk	4 hr
Jul 31, 4:41 PM CDT	Severe Thunderstorm Warning	FGF	Cass	49 min
Jul 31, 4:54 PM CDT	Severe Thunderstorm Warning	FGF	Polk	51 min
Jul 31, 4:58 PM CDT	Severe Thunderstorm Warning	FGF	Traill	32 min
Jul 31, 5:16 PM CDT	Severe Thunderstorm Warning	FGF	Lake of the Woods, Roseau	44 min
Jul 31, 5:39 PM CDT	Tornado Warning	FGF	Beltrami, Lake of the Woods	36 min
Jul 31, 6:05 PM CDT	Flash Flood Warning	FGF	Beltrami, Lake of the Woods, Marshall, Roseau	6 hr
Jul 31, 6:13 PM CDT	Severe Thunderstorm Warning	FGF	Clay	32 min
Jul 31, 6:15 PM CDT	Tornado Warning	FGF	Lake of the Woods	30 min
Jul 31, 6:23 PM CDT	Flash Flood Warning	FGF	Pennington, Polk, Red Lake	6 hr
Jul 31, 6:24 PM CDT	Severe Thunderstorm Warning	FGF	Norman	36 min
Jul 31, 6:54 PM CDT	Severe Thunderstorm Warning	FGF	Polk, Red Lake	36 min
Jul 31, 6:58 PM CDT	Severe Thunderstorm Warning	FGF	Norman	32 min
Jul 31, 7:30 PM CDT	Severe Thunderstorm Warning	FGF	Polk, Red Lake	30 min
Jul 31, 7:35 PM CDT	Severe Thunderstorm Warning	DLH	Koochiching	55 min
Jul 31, 7:58 PM CDT	Severe Thunderstorm Warning	FGF	Polk	32 min
Jul 31, 8:08 PM CDT	Severe Thunderstorm Warning	FGF	Clearwater	52 min
Jul 31, 8:23 PM CDT	Severe Thunderstorm Warning	FGF	Pennington	37 min
Jul 31, 8:43 PM CDT	Severe Thunderstorm Warning	FGF	Beltrami	32 min
Jul 31, 9:00 PM CDT	Severe Thunderstorm Warning	FGF	Marshall, Pennington	30 min

The nearest sounding before it

International Fa, MN (KINL), launched 12:00Z, 9.0 hours before the alert went out and 260 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: 2851 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 485 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 179 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 7.8

Open this sounding in Storm Lab

The text

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

923 
WWUS9 KMKC 312045
SEL6  
MKC WW 312035
MNZ000-NDZ000-010300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 646
STORM PREDICTION CENTER NORMAN OK
335 PM CDT TUE JUL 31 2001

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

   NORTHERN AND WESTERN MINNESOTA                          
   EASTERN NORTH DAKOTA                       

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 400 PM UNTIL 1000
PM 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 ALONG AND 90 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 25 MILES NORTHWEST OF JAMESTOWN NORTH DAKOTA
TO 20 MILES SOUTHEAST OF INTERNATIONAL FALLS MINNESOTA.

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.

DISCUSSION...THUNDERSTORMS EXPECTED TO DEVELOP/INCREASE INVOF FRONT
EXTENDING ENE FROM SURFACE LOW S OF BIS DURING THE NEXT FEW HOURS. 
SUFFICIENT SHEAR WILL BE PRESENT TO SUPPORT SUPERCELLS/BOWING
SEGMENTS.  PRESENCE OF RICH BOUNDARY LAYER MOISTURE AND BACKED
NEAR-SURFACE FLOW SUGGEST POTENTIAL FOR TORNADOES...ESPECIALLY WITH
ANY STORMS MOVING WELL TO RIGHT OF MEAN WIND.   

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 24030.

...CORFIDI

482,0990 494,0930 470,0930 455,0990

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 31, 4:45 AM CDT	Severe Thunderstorm Watch	SPC	Beltrami, Clearwater, Hubbard, Kittson, Lake of the Woods, Mahnomen and 6 more	3 hr
Jul 30, 11:45 PM CDT	Severe Thunderstorm Watch	SPC	Barnes, Cass, Dickey, Emmons, Foster, Grand Forks and 12 more	5 hr

Nearby

Tornado Watches in Minnesota, 2001 Tornado Watches in North Dakota, 2001 Every tornado watch in 2001

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.