Alert archive / Minnesota / Tornado Watches in 2001

Tornado Watch 137

April 11, 200118 counties in Minnesota; 14 counties in Wisconsin

The Storm Prediction Center issued this tornado watch at Apr 11, 2001, 5:30 PM CDT for 18 counties in Minnesota; 14 counties in Wisconsin. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Apr 11, 2001, 5:30 PM CDT (22:30 UTC)
Expired: Apr 11, 2001, 11:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 32 counties

Anoka County, MN, Dakota County, MN, Dodge County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Hennepin County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Ramsey County, MN, Rice County, MN, Scott County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Washington County, MN, Winona County, MN, Buffalo County, WI, Chippewa County, WI, Clark County, WI, Dunn County, WI, Eau Claire County, WI, Jackson County, WI, La Crosse County, WI, Monroe County, WI, Pepin County, WI, Pierce County, WI, Saint Croix County, WI, Taylor County, WI, Trempealeau County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 93 km from the middle of the area, began a volume at 22:31 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 11, 6:03 PM CDT	Severe Thunderstorm Warning	ARX	Fillmore, Olmsted	42 min

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 10.5 hours before the alert went out and 156 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: 5 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 454 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 130 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WWUS9 KMKC 112219
SEL7  

SEL7  
MKC WW 112212
MNZ000-WIZ000-120400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 137
STORM PREDICTION CENTER NORMAN OK
512 PM CDT WED APR 11 2001

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

   SOUTHEAST MINNESOTA                          
   WEST CENTRAL AND SOUTHWEST WISCONSIN                          

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 515 PM UNTIL
1100 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 85 STATUTE MILES EAST AND WEST
OF A LINE FROM 45 MILES NORTHWEST OF EAU CLAIRE WISCONSIN TO 40
MILES SOUTHWEST OF LA CROSSE WISCONSIN.

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 135...WW 136...

DISCUSSION...SUPERCELLS OVER ERN IA EXPECTED TO CONTINUE RAPIDLY
NNEWD THIS EVENING AS BOUNDARY WARM SECTOR SWEEPS NNW INTO SE
MN/WRN WI.  COOL LOW LEVEL AIR ORIGINATING OVER LK MI SHOULD LIMIT
NEWD PENETRATION OF SIGNIFICANT SEVERE INTO WI...WHILE STRONGEST
BOUNDARY LAYER WARMING/MOISTENING SURGES NNW UP THE MS RVR VLY.   

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 400. 
MEAN STORM MOTION VECTOR 23045.

...CORFIDI

;451,0902 432,0900 432,0933 451,0935;

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 11, 4:00 PM CDT	Tornado Watch	SPC	Crawford, Grant, Iowa, Lafayette	6 hr

Nearby

Tornado Watches in Minnesota, 2001 Tornado Watches in Wisconsin, 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.