Alert archive / Iowa / Tornado Watches in 2002

Tornado Watch 528

July 24, 200213 counties in Iowa; 6 counties in Minnesota; Burt County, Dakota County, Thurston County, Nebraska

The Storm Prediction Center issued this tornado watch at Jul 24, 2002, 8:25 PM CDT for 13 counties in Iowa; 6 counties in Minnesota; Burt County, Dakota County, Thurston County, Nebraska. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jul 24, 2002, 8:25 PM CDT (01:25 UTC)
Expired: Jul 25, 2002, 12:00 AM CDT
In force: 4 hr
Issued by: the Storm Prediction Center

All 22 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Burt County, NE, Dakota County, NE, Thurston County, NE

The radar

The Sioux Falls radar (KFSD), 115 km from the middle of the area, began a volume at 01:24 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

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

Issued	Product	Office	Counties	Lasted
Jul 24, 8:46 PM CDT	Severe Thunderstorm Warning	FSD	Rock	44 min
Jul 24, 9:27 PM CDT	Severe Thunderstorm Warning	FSD	Jackson	33 min

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.4 hours before the alert went out and 157 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: 735 J/kg
Mixed-layer CIN: -160 J/kg
Mixed-layer LCL: 2139 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 70 m²/s²
0-3 km storm-relative helicity: 310 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 250123
SEL8  
SPC WW 250125
IAZ000-MNZ000-NEZ000-250500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 528
STORM PREDICTION CENTER NORMAN OK
825 PM CDT WED JUL 24 2002

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

   NORTHWEST IOWA                               
   SOUTHWEST MINNESOTA                          
   NORTHEAST NEBRASKA                           

EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 825 PM
UNTIL MIDNIGHT 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 40 STATUTE MILES EAST AND WEST
OF A LINE FROM 50 MILES SOUTH SOUTHEAST OF SIOUX CITY IOWA TO 35
MILES NORTH OF WORTHINGTON 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 525...WW 526...WW 527...

DISCUSSION...INTENSE SUPERCELLS THUNDERSTORMS SERN SD EXPECTED TO
REMAIN A THREAT FOR ISOLATED TORNADOES AND DAMAGING WINDS AS WIND
PROFILES REMAIN VERY FAVORABLE AHEAD OF STORMS.  ACTIVITY WILL
DEVELOP/MOVE INTO NWRN IA AND ADJACENT MN AREA.


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 600. 
MEAN STORM MOTION VECTOR 29035.


...HALES

440,0944 414,0951 414,0964 440,0962

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 25, 3:05 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Audubon, Boone, Buena Vista, Calhoun and 37 more	5 hr
Jul 25, 12:25 AM CDT	Severe Thunderstorm Watch	SPC	Becker, Big Stone, Cass, Chippewa, Clay, Douglas and 12 more	4 hr
Jul 25, 3:45 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Banner, Chase, Cheyenne, Deuel, Dundy and 14 more	6 hr

Nearby

Tornado Watches in Iowa, 2002 Tornado Watches in Minnesota, 2002 Tornado Watches in Nebraska, 2002 Every tornado watch in 2002

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.