Alert archive / Iowa / Tornado Watches in 1997

Tornado Watch 551

July 1, 199754 counties in Iowa; Crawford County, Wisconsin

The Storm Prediction Center issued this tornado watch at Jul 1, 1997, 8:45 PM CDT for 54 counties in Iowa; Crawford County, Wisconsin. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jul 1, 1997, 8:45 PM CDT (01:45 UTC)
Expired: Jul 2, 1997, 2:00 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 55 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cedar County, IA, Cerro Gordo County, IA, Cherokee County, IA, Chickasaw County, IA, Clay County, IA, Clayton County, IA, Crawford County, IA, Delaware County, IA, Dickinson County, IA, Dubuque County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Ida County, IA, Jones County, IA, Kossuth County, IA, Linn County, IA, Lyon County, IA, Marshall County, IA, Mitchell County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Story County, IA, Tama County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Crawford County, WI

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 1, 8:56 PM CDT	Severe Thunderstorm Warning	ARX	Winneshiek	64 min
Jul 1, 9:24 PM CDT	Tornado Warning	ARX	Allamakee, Winneshiek	31 min
Jul 1, 9:53 PM CDT	Tornado Warning	ARX	Allamakee	37 min
Jul 1, 10:17 PM CDT	Tornado Warning	ARX	Crawford, Vernon	43 min
Jul 1, 10:29 PM CDT	Tornado Warning	ARX	Allamakee	31 min
Jul 1, 10:31 PM CDT	Tornado Warning	DVN	Delaware, Dubuque	59 min
Jul 1, 11:01 PM CDT	Tornado Warning	ARX	Crawford	49 min
Jul 1, 11:03 PM CDT	Severe Thunderstorm Warning	ARX	Clayton	57 min
Jul 1, 11:25 PM CDT	Tornado Warning	ARX	Clayton	45 min
Jul 1, 11:30 PM CDT	Tornado Warning	DVN	Dubuque	45 min
Jul 1, 11:52 PM CDT	Severe Thunderstorm Warning	ARX	Crawford	63 min

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 1.8 hours before the alert went out and 224 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: 1759 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 1186 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 303 m²/s²
0-3 km storm-relative helicity: 455 m²/s²
Significant tornado parameter: 4.3
Supercell composite: 21.5

Open this sounding in Storm Lab

The text

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

142 
WWUS9 KMKC 020122
SEL1  
MKC WW 020122
IAZ000-020700-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 551
STORM PREDICTION CENTER NORMAN OK
822 PM CDT TUE JUL 1 1997

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

   NORTHERN AND CENTRAL IOWA                             
 

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 845 PM
UNTIL 200 AM CDT.

TORNADOES...HAIL TO 2 1/2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS ALONG AND 60 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 25 MILES NORTH OF SIOUX CITY IOWA TO 70 MILES
NORTHEAST OF CEDAR RAPIDS IOWA.

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 550...

DISCUSSION...INDICATIONS ARE THAT THE CAP IS BEGINNING TO BREAK
ACROSS PORTIONS OF NORTHERN IA. A PAIR OF CELLS HAVE JUST DEVELOPED
OVER NORTHWEST IA ALONG THE DRY LINE. ALSO...THERE ARE SMALL
CUMULONIMBI DEVELOPING OVER NE IA. AIR MASS IS EXTREMELY
UNSTABLE...AND WIND FIELDS ARE BECOMING INCREASINGLY FAVORABLE FOR
SUPERCELLS. 



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 1/2 INCHES.  EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550.  MEAN STORM MOTION VECTOR 27025.


...VESCIO

433,0962 432,0904 414,0904 415,0962

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 1, 10:30 PM CDT	Tornado Watch	SPC	Dubuque	6 hr
Jul 1, 7:45 PM CDT	Tornado Watch	SPC	Barron, Buffalo, Burnett, Chippewa, Clark, Dunn and 12 more	5 hr

Nearby

Tornado Watches in Iowa, 1997 Tornado Watches in Wisconsin, 1997 Every tornado watch in 1997

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.