Tornadoes · United States · Iowa · 2005

F1 tornado, Hospers, Iowa, November 12, 2005

This F1 tornado ran 1.0 miles across Sioux County on November 12, 2005, touching down at 4:30 PM CST and reaching 100 yards wide. It killed nobody, and did $800,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mphthis tornado

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 mph

    Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

  4. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 mph

    Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

  7. Unrated

    The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating
F1
Date
November 12, 2005
Touchdown
4:30 PM CST (22:30 UTC)
Path length
1.0 miles (1.6 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
Property damage
$800,000
County
Sioux County
Touchdown point
43.070, -95.900
Lift-off point
43.070, -95.870
Record number
553

What the Weather Service recorded

A tornado destroyed the wall and part of the roof of a business in Hospers, and caused minor damage to contents in the building.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

The county was under a tornado watch, issued at 19:47 UTC and running to 00:08 UTC.

Issued (UTC)ExpiredProductOffice
19:47 UTC00:08 UTCTornado WatchFSD
22:01 UTC22:30 UTCSevere Thunderstorm WarningFSD
22:33 UTC23:00 UTCTornado WarningFSD
00:00 UTC14:50 UTCWind AdvisoryFSD

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:16 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Omaha, NE (KOAX), 12:00Z

10.5 hours before the tornado, 199 km from the path. November 12, 2005.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2005-11-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -106103, lifted condensation level 1049 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 12:00Z on 2005-11-12The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 155 square meters per square second, 0 to 6 km bulk shear 43 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-106103 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1049 m above ground
0-6 km bulk shear
43 kt
0-1 km bulk shear
30 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.5 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 00:00Z

1.5 hours after it, 199 km from the path. November 13, 2005.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2005-11-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -108143, lifted condensation level 1645 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 00:00Z on 2005-11-13The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 43 square meters per square second, 0 to 6 km bulk shear 33 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-108143 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1645 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
19 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
45 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.1 K/km

Open this sounding in Storm Lab

The surface observations

Sheldon (SHL), 16 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:35 UTC60.855.4170° 12 kt992.2HZ
20:40 UTC60.855.4170° 12 kt992.2
20:55 UTC60.855.4170° 12 kt17991.9HZ
21:00 UTC60.855.4170° 12 kt17991.9
21:15 UTC62.655.4170° 12 kt18991.5HZ
21:20 UTC62.655.4170° 12 kt18991.5
21:35 UTC62.655.4160° 10 kt991.2HZ
21:40 UTC62.655.4160° 10 kt991.2
21:55 UTC60.855.4160° 10 kt990.5HZ
22:00 UTC60.855.4160° 10 kt990.5
22:15 UTC60.855.4160° 12 kt990.5HZ
22:20 UTC60.855.4160° 12 kt990.5
22:35 UTC60.853.6150° 12 kt989.8+RA
22:40 UTC60.853.6150° 12 kt989.8
22:55 UTC55.450120° 7 kt22990.5RA
23:00 UTC55.450120° 7 kt22990.5
23:15 UTC55.450150° 4 kt990.2
23:20 UTC55.450150° 4 kt990.2
23:35 UTC55.450250° 14 kt19990.2
23:40 UTC55.450250° 14 kt19990.2
23:55 UTC53.648.2270° 24 kt31990.9
00:00 UTC53.648.2270° 24 kt31990.9
00:15 UTC5044.6270° 25 kt36991.5
00:20 UTC5044.6270° 25 kt36991.5

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Sioux Falls radar (KFSD), 89 km away, was scanning. The volume nearest the touchdown began at 22:27 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
22:10 UTCHAIL 0.752 S Rock ValleySioux, IA
22:30 UTCTORNADOHospersSioux, IATORNADO TOUCHED DOWN JUST WEST OF HOSPERS. TORNADO STRUCK A BUSINESS IN THE SOUTHWEST CORNER OF HOSPERS REMOVING A WALL AND PART OF THE ROOF.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2005 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of November 12, 2005

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
November 123:50 PM CSTF1Greene, IA1.045$10,000
November 124:26 PM CSTF2Dallas, IA14.01002$3.3 million
November 124:27 PM CSTF3Boone, IA17.615013$12 million
November 124:48 PM CSTF1Boone, IA6.075$200,000
November 124:56 PM CSTF0Story, IA0.230$2,000
November 124:58 PM CSTF2Boone, IA12.01001$350,000
November 125:15 PM CSTF0Story, IA1.650$50,000
November 125:20 PM CSTF1Story, IA8.075$730,000
November 125:27 PM CSTF0Hamilton, IA1.530$10,000
November 125:50 PM CSTF0Hardin, IA0.730$10,000
November 126:40 PM CSTF1Monroe, IA1.550$50,000
November 127:40 PM CSTF1Lawrence, MO5.0751$750,000
November 1210:27 PM CSTF0Polk, AR3.530

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.