Alert archive / Iowa / Tornado Warnings in 2001

Tornado Warning 8, NWS Omaha, NE

April 11, 2001Harrison County, Iowa

NWS Omaha, NE issued this tornado warning at Apr 11, 2001, 1:04 PM CDT for Harrison County, Iowa. It was in force for 26 min. 1 report 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: Apr 11, 2001, 1:04 PM CDT (18:04 UTC)
Expired: Apr 11, 2001, 1:30 PM CDT
In force: 26 min
Issued by: NWS Omaha, NE
Area: Whole counties

County Harrison County, IA

The radar

The Omaha radar (KOAX), 61 km from the middle of the area, began a volume at 18:06 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	Remark
Apr 11, 1:30 PM CDT	Thunderstorm Wind 60 E	Little Sioux, IA	Thunderstorm wind gust over 60 mph blew the windows out of some outbuildings north of Little Sioux, Iowa. From the same mini-supercell which produced the tornadoes near Crescent, Treynor and Mineola, Iowa. Reported by a cooperative observer.

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
Apr 11, 10:45 AM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 6.1 hours before the alert went out and 61 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1274 m above ground
0-6 km bulk shear: 77 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 163 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.

000 
WFUS53 KOAX 111807
TOROMA
IAC085-111830-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE OMAHA NE
104 PM CDT WED APR 11 2001

THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A

* TORNADO WARNING FOR...
  HARRISON COUNTY IN SOUTHWEST IOWA

* UNTIL 130 PM CDT

* AT 100 PM CDT...A TORNADO WAS REPORTED ON THE GROUND SOUTHEAST OF 
CRESCENT MOVING NORTHEAST AT 40 MPH.  

* THE TORNADO IS EXPECTED TO BE NEAR...
  MISSOURI VALLEY AROUND 115 PM CDT
  LOGAN 130 PM CDT

TAKE SHELTER IMMEDIATELY IF YOU ARE IN THE PATH OF THIS STORM.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 400 PM CDT WEDNESDAY
AFTERNOON FOR SOUTHWESTERN IOWA AND EASTERN NEBRASKA.

LAT...LON 415y1 9595 4154 9568 4159 9556 4175 9587


ZAPOTOCNY

The office that day

Everything else NWS Omaha, NE issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 11, 12:20 AM CDT	Severe Thunderstorm Warning	OAX	Monona	40 min
Apr 11, 3:21 AM CDT	Severe Thunderstorm Warning	OAX	Fremont	39 min
Apr 11, 3:34 AM CDT	Severe Thunderstorm Warning	OAX	Mills	41 min
Apr 11, 3:45 AM CDT	Severe Thunderstorm Warning	OAX	Montgomery, Page	45 min
Apr 11, 3:57 AM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	48 min
Apr 11, 12:38 PM CDT	Tornado Warning	OAX	Mills	37 min
Apr 11, 12:45 PM CDT	Tornado Warning	OAX	Pottawattamie	30 min
Apr 11, 1:12 PM CDT	Tornado Warning	OAX	Pottawattamie	18 min
Apr 11, 1:29 PM CDT	Tornado Warning	OAX	Shelby	31 min
Apr 11, 1:30 PM CDT	Tornado Warning	OAX	Harrison	30 min
Apr 11, 1:40 PM CDT	Tornado Warning	OAX	Monona	35 min

Nearby

Tornado Warnings in Iowa, 2001 Every tornado warning in 2001 Tornadoes 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.