Alert archive / Iowa / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 49, NWS Sioux Falls, SD

April 18, 2004O'Brien County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Apr 18, 2004, 6:38 PM CDT for O'Brien County, Iowa. It was in force for 67 min. 4 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Apr 18, 2004, 6:38 PM CDT (23:38 UTC)
Expired: Apr 18, 2004, 7:45 PM CDT
In force: 67 min
Issued by: NWS Sioux Falls, SD
Area: Counties, with a storm outline in the text

County O'Brien County, IA

The radar

The Sioux Falls radar (KFSD), 99 km from the middle of the area, began a volume at 23:38 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
Apr 18, 6:38 PM CDT	HAIL 0.75	Sheldon, A
Apr 18, 7:09 PM CDT	TSTM WND GST 60	Archer, A
Apr 18, 7:09 PM CDT	HAIL 0.88	Archer, A
Apr 18, 7:13 PM CDT	TSTM WND GST 60	Archer, A

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

Issued	Product	Office	Lasted
Apr 18, 4:40 PM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.6 hours before the alert went out and 208 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: 256 J/kg
Mixed-layer CIN: -464 J/kg
Mixed-layer LCL: 995 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 365 m²/s²
0-3 km storm-relative helicity: 406 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.

995 
WUUS53 KFSD 182338
SVRFSD
IAC141-190045-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
638 PM CDT SUN APR 18 2004

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  OBRIEN COUNTY IN NORTHWEST IOWA

* UNTIL 745 PM CDT

* AT 633 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING NICKEL SIZE
  HAIL...AND DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THESE STORMS
  WERE LOCATED ALONG A LINE EXTENDING FROM 7 MILES NORTHWEST OF
  SANBORN TO 18 MILES WEST OF PAULLINA...OR FROM 23 MILES NORTHEAST
  OF ORANGE CITY TO 4 MILES SOUTH OF ORANGE CITY...MOVING EAST AT 25
  MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  ARCHER AROUND 645 PM CDT
  SANBORN AROUND 650 PM CDT
  PRIMGHAR AROUND 700 PM CDT
  PAULLINA...HARTLEY AROUND 705 PM CDT
  SUTHERLAND AROUND 720 PM CDT

THIS STORM WILL PRODUCE LARGE HAIL AND DAMAGING WIND. GO INSIDE A
STURDY BUILDING AND STAY AWAY FROM WINDOWS.

LAT...LON 4325 9584 4292 9586 4293 9546 4325 9541

$$

BOUSTEAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 18, 4:04 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	26 min
Apr 18, 4:20 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	25 min
Apr 18, 4:45 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	30 min
Apr 18, 4:56 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	49 min
Apr 18, 5:18 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	42 min
Apr 18, 5:51 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	24 min
Apr 18, 5:59 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	61 min
Apr 18, 6:19 PM CDT	Severe Thunderstorm Warning	FSD	Osceola	56 min
Apr 18, 6:26 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	64 min
Apr 18, 6:55 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	50 min
Apr 18, 6:59 PM CDT	Severe Thunderstorm Warning	FSD	Dickinson	46 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2004 Every severe thunderstorm warning in 2004

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.