Alert archive / South Dakota / Severe Thunderstorm Watches in 1997

Severe Thunderstorm Watch 721

September 1, 199717 counties in Nebraska; 29 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Sep 1, 1997, 2:30 PM CDT for 17 counties in Nebraska; 29 counties in South Dakota. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Sep 1, 1997, 2:30 PM CDT (19:30 UTC)
Expired: Sep 1, 1997, 8:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 46 counties

Antelope County, NE, Blaine County, NE, Boyd County, NE, Brown County, NE, Cedar County, NE, Custer County, NE, Dixon County, NE, Garfield County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Logan County, NE, Loup County, NE, Pierce County, NE, Rock County, NE, Thomas County, NE, Wheeler County, NE, Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Deuel County, SD, Douglas County, SD, Gregory County, SD, Hamlin County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, Lyman County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Tripp County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 177 km from the middle of the area, began a volume at 19:31 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

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

Issued	Product	Office	Counties	Lasted
Sep 1, 6:13 PM CDT	Severe Thunderstorm Warning	LBF	Thomas	47 min
Sep 1, 7:51 PM CDT	Severe Thunderstorm Warning	LBF	Blaine, Custer	64 min

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 7.5 hours before the alert went out and 188 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: 1775 J/kg
Mixed-layer CIN: -205 J/kg
Mixed-layer LCL: 910 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 201 m²/s²
0-3 km storm-relative helicity: 204 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

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

915 
WWUS9 KMKC 011904
SEL1  
MKC WW 011904
SDZ000-NEZ000-020100-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 721
STORM PREDICTION CENTER NORMAN OK
204 PM CDT MON SEP 1 1997

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   EASTERN AND SOUTH CENTRAL SOUTH DAKOTA                       
   NORTHEASTERN AND CENTRAL NEBRASKA                           

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 800
PM CDT.

HAIL TO 1 3/4 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 90 STATUTE MILES
NORTH AND SOUTH OF A LINE FROM 30 MILES WEST SOUTHWEST OF AINSWORTH
NEBRASKA TO 25 MILES NORTHEAST OF SIOUX FALLS SOUTH DAKOTA.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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 720...

DISCUSSION...STRONG COLD FRONT AND UPPER VORT AXIS MOVING INTO
MOIST UNSTABLE AIR WHERE CAPES EXCEED 3000 J/KG. 30 TO 40 KT MID
LEVEL FLOW AND MID LEVEL DRY LAYER INDICATES POTENTIAL FOR LARGE
HAIL AND DAMAGING DOWNBURSTS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 3/4 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM
MOTION VECTOR 26030.


...ROGASH

434,1003 450,0962 423,0962 410,1003

Nearby

Severe Thunderstorm Watches in South Dakota, 1997 Severe Thunderstorm Watches in Nebraska, 1997 Every severe thunderstorm 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; radar from the NEXRAD Level II archive.