Alert archive / Iowa / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 14, NWS Sioux Falls, SD

April 11, 2001Woodbury County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Apr 11, 2001, 12:38 AM CDT for Woodbury County, Iowa. It was in force for 37 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.

The facts

Issued: Apr 11, 2001, 12:38 AM CDT (05:38 UTC)
Expired: Apr 11, 2001, 1:15 AM CDT
In force: 37 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Woodbury County, IA

The radar

The Omaha radar (KOAX), 108 km from the middle of the area, began a volume at 05:39 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 5.6 hours before the alert went out and 108 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: 18 J/kg
Mixed-layer CIN: -145 J/kg
Mixed-layer LCL: 493 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 131 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.6

Open this sounding in Storm Lab

The text

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

463 
WUUS53 KFSD 110538
SVRFSD
IAC193-110615-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1238 AM CDT WED APR 11 2001

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

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

* UNTIL 115 AM CDT

* AT 1238 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 7 MILES WEST OF SLOAN...OR ABOUT 20 MILES SOUTH
  OF SIOUX CITY...MOVING NORTHEAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  SALIX...SLOAN AROUND 1245 AM CDT
  LAWTON AROUND 105 AM CDT

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

LAT...LON 4220 9639 4218 9635 4235 9595 4251 9618

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 Apr 10, 9:25 PM CDT, 3 hours 13 minutes earlier.

Area forecast discussion, Apr 10, 9:25 PM CDT, 3 hours 13 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
925 PM CDT TUE APR 10 2001

KFSD 88D SHOWING BANDS OF MAINLY SHOWERS DEVELOPING ACROSS NORTHERN
AND WESTERN CWA IN AREA OF INCREASING WARM ADVECTION PER 18Z MESOETA
FORECAST.  LARGER AREA OF SHOWERS AND THUNDERSTORMS IN SOUTHEAST CWA
HAS BEEN DIMINISHING IN THE COUPLE OF HOURS...BUT DID PRODUCE A FEW
REPORTS OF PEA-DIME SIZE HAIL EARLIER THIS EVENING.

CONCERN AT THIS POINT IS STRONGER CELLS DEVELOPING ON KUEX/KOAX 88DS
ALONG 850MB WARM FRONT.  CURRENT MOVEMENT ON STRONGEST CELL IN NERN
PART OF KUEX CWA WOULD BRING IT INTO OUR FAR SRN CWA AFTER MIDNIGHT.
HOWEVER OTHER ACTIVITY ALSO DEVELOPING JUST SOUTH OF CWA WEST OF
DENISON.  LATEST SWOMCD BRINGS RISK OF SEVERE TSRA INTO OUR FAR SRN
COUNTIES...WHICH DOES NOT SEEM UNREASONABLE.

WILL LIKELY UPDATE ZONES TO TWEAK WORDING/TIMING OF SHRA DEVELOPMENT
IN NWRN CWA...BUT MAY WAIT A LITTLE WHILE TO SEE IF SPC DECIDES TO
ACT ON SWOMCD.

.FSD...NONE
 HAMEN

In the hours before

Local storm report, Apr 10, 10:16 PM CDT, 2 hours 22 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1016 PM CDT TUE APR 10 2001

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0549 PM    3 W PAULLINA              IA   .75 INCH HAIL
04/10/01   OBRIEN                         REPORTED BY MEDIA.

0558 PM    ORANGE CITY               IA   .75 INCH HAIL
04/10/01   SIOUX                          REPORTED BY STORM
  f                                        SPOTTER.

0615 PM    BOYDEN                    IA   .75 INCH HAIL
04/10/01   SIOUX                          REPORTED BY STORM
                                          SPOTTER.

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 11, 1:56 PM CDT	Tornado Warning	FSD	Woodbury	34 min
Apr 11, 2:28 PM CDT	Tornado Warning	FSD	Woodbury	32 min
Apr 11, 2:37 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida	23 min
Apr 11, 2:58 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	32 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2001 Every severe thunderstorm warning in 2001

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.