Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 231, NWS Sioux Falls, SD

August 24, 1998Lyon County, Sioux County, Iowa; Rock County, Minnesota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 24, 1998, 9:19 AM CDT for Lyon County, Sioux County, Iowa; Rock County, Minnesota. It was in force for 61 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: Aug 24, 1998, 9:19 AM CDT (14:19 UTC)
Expired: Aug 24, 1998, 10:20 AM CDT
In force: 61 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties

Counties Lyon County, IA, Sioux County, IA, Rock County, MN

The radar

The Sioux Falls radar (KFSD), 48 km from the middle of the area, began a volume at 14:19 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
Aug 24, 9:32 AM CDT	Thunderstorm Wind 52	Lester, IA
Aug 24, 9:32 AM CDT	Hail 1	Lester, IA
Aug 24, 9:32 AM CDT	Hail 2	Rock Rapids, 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 24, 7:45 AM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 2.3 hours before the alert went out and 229 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: 377 J/kg
Mixed-layer CIN: -480 J/kg
Mixed-layer LCL: 2119 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: -145 m²/s²
0-3 km storm-relative helicity: -145 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

670 
WUUS1 KFSD 241420 RRA
SVRFSD
IAC119-167-MNC133-241520-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
919 AM CDT MON AUG 24 1998

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  ROCK COUNTY IN SOUTHWESTERN MINNESOTA
  LYON COUNTY IN NORTHWESTERN IOWA
  SIOUX COUNTY IN NORTHWESTERN IOWA

* UNTIL 1020 AM CDT

* AT 915 AM CDT... NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A LINE OF SEVERE THUNDERSTORMS FROM 8 MILES EAST OF SIOUX FALLS
  TO 5 MILES SOUTHWEST OF CANTON MOVING EAST AT 50 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  KLONDIKE                 AROUND 925 AM CDT
  LARCHWOOD                AROUND 925 AM CDT
  BRUCE                    AROUND 925 AM CDT
  LESTER                   AROUND 930 AM CDT
  ALVORD                   AROUND 930 AM CDT
  STEEN                    AROUND 930 AM CDT
  ROCK RAPIDS              AROUND 940 AM CDT


IF YOU ARE CAUGHT OUTSIDE... SEEK REFUGE FROM THE STORM IN A
STRONG BUILDING. BOATERS ON AREA LAKES SHOULD TAKE SHELTER.
DAMAGING WIND... LARGE HAIL... VERY HEAVY RAIN... AND DANGEROUS
LIGHTNING ARE ALL LIKELY. DO NOT SEEK SHELTER UNDER TREES OR OTHER
ISOLATED TALL OBJECTS. THESE ATTRACT LIGHTNING. DO NOT DRIVE INTO
AREAS WHERE WATER COVERS THE ROAD.

FUHS

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 23, 9:15 PM CDT, 12 hours 4 minutes earlier.

Area forecast discussion, Aug 23, 9:15 PM CDT, 12 hours 4 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
915 PM CDT SUN AUG 23 1998

INDEPTH HAND UPR ANLYS SHOWS UNDERFCST SHORT WV MOVG EWD THRU MONT AND
WY TNGT WITH RAPID DVLPMT OF WRM ADV SCT TSTMS INTO SW SD AND NW NEB
THIS EVE MOVG ENEWD. SINCE I UPDATED FOR HIGHER POPS LATE TNGT IN CWA
AND LOOKS LIKE YET HIGHER POPS FOR MON...WL GO INTO SECOND PERIOD OF
FCST TO BEEF UP WORDING...AND ALSO TO GO ALG WITH EARLY EVE QPF.
MOISTURE AVBL WITH THIS SYS WL BE RELATIVELY DEEP FEEDING NWD FM ERN
NEB AND KS THRU MON AND LCLLY HVY RAIN QUITE PSBL SOMEWHERE IN CWA...
BUT WHETHER IT IS TO THE N OR S IS A QUESTION AND WL NOT GO HIGHER
THAN 50 PCT POPS. CLDS AND PRECIP MAY ALSO INHIBIT TEMPS IN SOME AREAS
OF CWA ON MON. NO USE WAITING FOR MODELS THIS EVE AS THEY HAVE NOT
BEEN A LOT OF HELP WITH CONVECTION.

.FSD...NONE
RYRHOLM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 24, 8:01 AM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson	34 min
Aug 24, 9:22 AM CDT	Tornado Warning	FSD	Sioux	48 min
Aug 24, 8:20 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood	50 min
Aug 24, 8:36 AM CDT	Severe Thunderstorm Warning	FSD	Jackson	49 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1998 Severe Thunderstorm Warnings in Minnesota, 1998 Every severe thunderstorm warning 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.