Alert archive / Iowa / Tornado Warnings in 2001

Tornado Warning 7, NWS Omaha, NE

April 11, 2001Pottawattamie County, Iowa

NWS Omaha, NE issued this tornado warning at Apr 11, 2001, 12:45 PM CDT for Pottawattamie County, Iowa. It was in force for 30 min. 2 reports came from 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, with what was reported inside it.

The facts

Issued: Apr 11, 2001, 12:45 PM CDT (17:45 UTC)
Expired: Apr 11, 2001, 1:15 PM CDT
In force: 30 min
Issued by: NWS Omaha, NE
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Pottawattamie County, IA

The radar

The Omaha radar (KOAX), 63 km from the middle of the area, began a volume at 17:45 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, 12:55 PM CDT	Tornado F1	Carson, IA	This tornado was caught on film by a storm chaser. Two large barns and an outbuilding were destroyed, and a roof was taken off of a house. From the same mini-supercell that first produced a tornado near Emerson, Iowa.
Apr 11, 12:55 PM CDT	Tornado F0	Treynor, IA	This tornado was caught on film by a storm chaser as it touched down in open country west of Treynor, Iowa. From the same mini-supercell which produced the tornado near Mineola, Iowa.

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, 5.8 hours before the alert went out and 63 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 111746
TOROMA
IAC155-111815-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE OMAHA NE
1245 PM CDT WED APR 11 2001

THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A

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

* UNTIL 115 PM CDT

* AT 1240 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  TORNADO NEAR GLENWOOD IOWA AND A SECOND TORNADO NEAR EMERSON 
IOWA...MOVING NORTH AT 40 MPH.  IN ADDITION...THE PUBLIC HAS 
REPORTED FUNNEL CLOUDS AT THESE LOCATIONS.

* THE TORNADO IS EXPECTED TO BE NEAR...
  TREYNOR AROUND 1255 PM CDT
  OAKLAND AROUND 1255 PM CDT

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

LAT...LON 4119 9584 4117 9544 4130 9539 4145 9560

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, 1:04 PM CDT	Tornado Warning	OAX	Harrison	26 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.