Alert archive / Minnesota / Tornado Watches in 1998

Tornado Watch 751

July 18, 19986 counties in Iowa; 22 counties in Minnesota; 10 counties in South Dakota

The Storm Prediction Center issued this tornado watch at Jul 18, 1998, 8:45 PM CDT for 6 counties in Iowa; 22 counties in Minnesota; 10 counties in South Dakota. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jul 18, 1998, 8:45 PM CDT (01:45 UTC)
Expired
Jul 19, 1998, 3:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 38 counties

Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Sioux County, IA, Big Stone County, MN, Brown County, MN, Chippewa County, MN, Cottonwood County, MN, Jackson County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Lincoln County, MN, Lyon County, MN, Meeker County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Pope County, MN, Redwood County, MN, Renville County, MN, Rock County, MN, Stearns County, MN, Stevens County, MN, Swift County, MN, Traverse County, MN, Yellow Medicine County, MN, Brookings County, SD, Deuel County, SD, Grant County, SD, Hamlin County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Moody County, SD, Turner County, SD

The radar

The Sioux Falls radar (KFSD), 74 km from the middle of the area, began a volume at 01:45 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.

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 18, 8:50 PM CDTSevere Thunderstorm WarningFSDMcCook35 min
Jul 18, 9:05 PM CDTTornado WarningMPXStevens60 min
Jul 18, 9:09 PM CDTSevere Thunderstorm WarningFSDMinnehaha31 min
Jul 18, 9:28 PM CDTSevere Thunderstorm WarningFSDLincoln, Turner32 min
Jul 18, 9:31 PM CDTSevere Thunderstorm WarningFSDLyon34 min
Jul 18, 9:39 PM CDTSevere Thunderstorm WarningFSDMinnehaha11 min
Jul 18, 9:45 PM CDTSevere Thunderstorm WarningFSDSioux45 min
Jul 18, 9:47 PM CDTSevere Thunderstorm WarningMPXRedwood33 min
Jul 18, 9:55 PM CDTSevere Thunderstorm WarningFSDNobles45 min
Jul 18, 10:03 PM CDTSevere Thunderstorm WarningMPXStevens, Swift62 min
Jul 18, 10:06 PM CDTSevere Thunderstorm WarningMPXBrown, Watonwan49 min
Jul 18, 10:07 PM CDTSevere Thunderstorm WarningFSDLyon, Osceola33 min
Jul 18, 10:23 PM CDTSevere Thunderstorm WarningFSDO'Brien32 min
Jul 18, 10:41 PM CDTSevere Thunderstorm WarningFSDClay, Dickinson29 min
Jul 18, 11:39 PM CDTSevere Thunderstorm WarningFSDMcCook31 min
Jul 19, 12:08 AM CDTSevere Thunderstorm WarningFSDTurner32 min

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 1.8 hours before the alert went out and 185 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-pSkew-T log-p diagram, Aberdeen, SD at 00:00Z on 1998-07-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2715 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Aberdeen, SD at 00:00Z on 1998-07-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -26 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2715 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
1730 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
-26 m²/s²
0-3 km storm-relative helicity
-4 m²/s²
Significant tornado parameter
-0.1
Supercell composite
-1.6

Open this sounding in Storm Lab

The text

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

000 
WWUS9 KMKC 190118 
MKC WW 190118 
MNZ000-SDZ000-IAZ000-190800-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 751
STORM PREDICTION CENTER NORMAN OK
818 PM CDT SAT JUL 18 1998

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

WEST CENTRAL AND SOUTHWEST MINNESOTA
EASTERN SOUTH DAKOTA
NORTHWEST IOWA

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 845 PM UNTIL
300 AM CDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 70 STATUTE MILES EAST AND WEST
OF A LINE FROM 40 MILES SOUTH SOUTHEAST OF SIOUX FALLS SOUTH DAKOTA
TO ALEXANDRIA 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...THIS TORNADO WATCH REPLACES TORNADO WATCH
NUMBER 750.  WATCH NUMBER 750 WILL NOT BE IN EFFECT AFTER 845 PM
CDT.  CONTINUE...WW 749...

DISCUSSION...BAND OF INTENSE THUNDERSTORMS...SOME WITH
ROTATION..CONTINUE TO MOVE EASTWARD TO EAST SOUTHEASTWARD ALONG AND
JUST NORTH OF QUASISTATIONARY FRONT IN VERY UNSTABLE AIRMASS.  VAD
WINDS AT MPX AND FSD SUGGEST SUPERCELLS ARE POSSIBLE.  HOWEVER...
ACTIVITY MAY EVANTUALLY EVOLVE INTO A BOW ECHO.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. 
MEAN STORM MOTION VECTOR 28035.


...JOHNS

;430,0974 455,0965 455,0935 430,0950;

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 18, 10:30 PM CDTSevere Thunderstorm WatchSPCBremer, Buena Vista, Butler, Cerro Gordo, Chickasaw, Emmet and 14 more6 hr
Jul 19, 1:30 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 10 more6 hr

Nearby

Tornado Watches in Minnesota, 1998Tornado Watches in South Dakota, 1998Tornado Watches in Iowa, 1998Every 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.