Alert archive / South Dakota / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 9, NWS Sioux Falls, SD

May 3, 1999Clay County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 3, 1999, 10:11 PM CDT for Clay County, South Dakota. It was in force for 34 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 3, 1999, 10:11 PM CDT (03:11 UTC)
Expired: May 3, 1999, 10:45 PM CDT
In force: 34 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties

County Clay County, SD

The watch it was issued in

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

Issued	Product	Office	Lasted
May 3, 9:00 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 3.2 hours before the alert went out and 184 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: 1468 J/kg
Mixed-layer CIN: -16 J/kg
Mixed-layer LCL: 1303 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 89 m²/s²
0-3 km storm-relative helicity: 242 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 6.5

Open this sounding in Storm Lab

The text

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

999 
WUUS1 KFSD 040310 RRA
SVRFSD
SDC027-040345-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1011 PM CDT MON MAY 3 1999

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CLAY COUNTY IN SOUTHEASTERN SOUTH DAKOTA

* UNTIL 1045 PM CDT

* AT 1009 PM CDT... NATIONAL WEATHER SERVICE DOPPLER RADAR
  INDICATED A SEVERE THUNDERSTORM WITH LARGE HAIL 14 MILES EAST OF
  YANKTON OR 11 MILES SOUTHWEST OF WESTERVILLE... MOVING NORTH AT
  30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MECKLING                 AROUND 1015 PM CDT
  WESTERVILLE              AROUND 1030 PM CDT
  WAKONDA                  AROUND 1040 PM CDT

THIS IS A DANGEROUS STORM. STAY INDOORS AWAY FROM WINDOWS.

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 May 3, 9:50 PM CDT, 21 minutes earlier.

Area forecast discussion, May 3, 9:50 PM CDT, 21 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
950 PM CDT MON MAY 3 1999

LN OF STG TSTMS MOVG NNE INTO SERN SD ATTM...SEEMS TO BE STAYING W OF
IA/MN BORDER ATTM...BUT COULD DO A RIGHT TURN WITH TIME. SEEMS TO BE
ASSCD WITH A VORT LOBE ROTATING AHEAD OF MAIN SYS AND THERE SHUD BE
BRK BEHIND IT AFT 2 AM AFT WATCH EXPIRES. UPDATED EARLIER FOR WATCH
AND NO POPS...BUT STILL WENT SCT AS OVERALL COVERAGE SHUD DCRS BY 2 AM.

.FSD...NONE
RYRHOLM

The office that day

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

Issued	Product	Office	Counties	Lasted
May 3, 9:11 PM CDT	Severe Thunderstorm Warning	FSD	Gregory	34 min
May 3, 9:23 PM CDT	Severe Thunderstorm Warning	FSD	Yankton	32 min
May 3, 9:40 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Charles Mix	50 min
May 3, 9:49 PM CDT	Tornado Warning	FSD	Yankton	31 min
May 3, 9:54 PM CDT	Severe Thunderstorm Warning	FSD	Gregory	36 min
May 3, 10:22 PM CDT	Severe Thunderstorm Warning	FSD	Hutchinson, Yankton	38 min
May 3, 10:27 PM CDT	Tornado Warning	FSD	Clay	33 min
May 3, 10:33 PM CDT	Severe Thunderstorm Warning	FSD	Douglas	47 min
May 3, 10:46 PM CDT	Tornado Warning	FSD	Clay	34 min
May 3, 11:00 PM CDT	Severe Thunderstorm Warning	FSD	Turner	35 min
May 3, 11:47 PM CDT	Severe Thunderstorm Warning	FSD	Minnehaha	33 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 1999 Every severe thunderstorm warning in 1999

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.