Alert archive / Minnesota / Tornado Watches in 1998

Tornado Watch 761

July 20, 199840 counties in Minnesota; Deuel County, South Dakota

The Storm Prediction Center issued this tornado watch at Jul 20, 1998, 5:45 PM CDT for 40 counties in Minnesota; Deuel County, South Dakota. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jul 20, 1998, 5:45 PM CDT (22:45 UTC)
Expired: Jul 20, 1998, 11:00 PM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 41 counties

Anoka County, MN, Benton County, MN, Big Stone County, MN, Brown County, MN, Carver County, MN, Chippewa County, MN, Chisago County, MN, Dakota County, MN, Dodge County, MN, Douglas County, MN, Goodhue County, MN, Grant County, MN, Hennepin County, MN, Isanti County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Le Sueur County, MN, McLeod County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Nicollet County, MN, Pope County, MN, Ramsey County, MN, Redwood County, MN, Renville County, MN, Rice County, MN, Scott County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Steele County, MN, Stevens County, MN, Swift County, MN, Todd County, MN, Traverse County, MN, Washington County, MN, Wilkin County, MN, Wright County, MN, Yellow Medicine County, MN, Deuel County, SD

The radar

The Minneapolis radar (KMPX), 139 km from the middle of the area, began a volume at 22:45 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.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 10.8 hours before the alert went out and 137 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2372 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 103 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.

139 
WWUS9 KMKC 202226
SEL1  
MKC WW 202226
MNZ000-210400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 761
STORM PREDICTION CENTER NORMAN OK
526 PM CDT MON JUL 20 1998

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

   SOUTHERN MINNESOTA                          

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 545 PM UNTIL 1100
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 65 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 70 MILES WEST SOUTHWEST OF ALEXANDRIA
MINNESOTA TO 25 MILES EAST OF MINNEAPOLIS 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.

OTHER WATCH INFORMATION...  CONTINUE...WW 759...WW 760...

DISCUSSION...LINE OF THUNDERSTORMS WILL INCREASE AS IT MOVES
SOUTHEASTWARD INTO WATCH AREA...ALONG COLD FRONT AND AHEAD OF UPPER
SHORT WAVE. AIR MASS VERY UNSTABLE WITH CAPES EXCEEDING 4000 J/KG.
VEERING WIND PROFILE AND 40 KT MID LEVEL FLOW WILL PROVIDE
FAVORABLE SHEAR FOR A FEW TORNADIC SUPERCELLS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. 
MEAN STORM MOTION VECTOR 29035.

...ROGASH

462,0964 454,0924 435,0924 443,0964

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 2:15 PM CDT	Tornado Watch	SPC	Aitkin, Becker, Beltrami, Carlton, Cass, Clay and 21 more	6 hr
Jul 20, 4:00 PM CDT	Severe Thunderstorm Watch	SPC	Fillmore, Houston, Olmsted, Winona	5 hr

Nearby

Tornado Watches in Minnesota, 1998 Tornado Watches in South Dakota, 1998 Every tornado watch in 1998

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.