Alert archive / Iowa / Tornado Warnings in 1998

Tornado Warning 15, NWS Sioux Falls, SD

May 28, 1998Plymouth County, Woodbury County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 28, 1998, 7:20 PM CDT for Plymouth County, Woodbury County, Iowa. It was in force for 30 min. 3 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: May 28, 1998, 7:20 PM CDT (00:20 UTC)
Expired: May 28, 1998, 7:50 PM CDT
In force: 30 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties

Counties Plymouth County, IA, Woodbury County, IA

The radar

The Sioux Falls radar (KFSD), 124 km from the middle of the area, began a volume at 00:19 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.

What was reported inside it

Time	Report	Where
May 28, 7:20 PM CDT	Hail 1.75	Sioux City, IA
May 28, 7:30 PM CDT	Hail 2.5	Le Mars, IA
May 28, 7:55 PM CDT	Hail 0.75	Hinton, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.3 hours before the alert went out and 140 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: 2835 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 1954 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 7.5

Open this sounding in Storm Lab

The text

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

341 
WFUS1 KFSD 290020 RRA
TORFSD
IAC149-193-290050-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
720 PM CDT THU MAY 28 1998

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  WESTERN PLYMOUTH COUNTY IN NORTHWESTERN IOWA
  WESTERN WOODBURY COUNTY IN NORTHWESTERN IOWA

* UNTIL 750 PM CDT

* AT 717 PM CDT... NATIONAL WEATHER SERVICE SPOTTERS REPORTED A
  DEVELOPING TORNADO 9 MILES NORTHWEST OF SIOUX CITY  OR 9 MILES
  WEST OF JAMES MOVING EAST AT 35 MPH.

* THE TORNADO IS EXPECTED TO BE NEAR...
  NORTH SIOUX CITY         AROUND 725 PM CDT
  JAMES                    AROUND 725 PM CDT
  HINTON                   AROUND 725 PM CDT
  NEPTUNE                  AROUND 740 PM CDT



IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A NEARBY REINFORCED
BUILDING.  AS A LAST RESORT...SEEK SHELTER IN A CULVERT...DITCH OR
LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

HOLMES
&

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 28, 7:12 PM CDT	Tornado Warning	FSD	Cherokee	33 min
May 28, 7:42 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	33 min
May 28, 7:52 PM CDT	Tornado Warning	FSD	Plymouth, Woodbury	33 min
May 28, 8:26 PM CDT	Tornado Warning	FSD	Woodbury	34 min
May 28, 9:04 PM CDT	Tornado Warning	FSD	Woodbury	31 min

Nearby

Tornado Warnings in Iowa, 1998 Every tornado warning in 1998 Tornadoes 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.