Tornadoes · United States · Montana · 1999
F2 tornado, Baker, Montana, June 20, 1999
This F2 tornado ran 5.0 miles across Fallon County on June 20, 1999, touching down at 8:00 PM MDT and reaching 300 yards wide. It killed nobody.
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.
F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
F2113 to 157 mphthis tornado
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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
- F2
- Date
- June 20, 1999
- Touchdown
- 8:00 PM MDT (02:00 UTC)
- Path length
- 5.0 miles (8.0 km)
- Path width
- 300 yards (274 m)
- Deaths
- 0
- Injuries
- 0
- County
- Fallon County
- Touchdown point
- 46.530, -104.180
- Lift-off point
- 46.630, -104.280
- Record number
- 356
What the Weather Service recorded
A large tornado which touched down near Ollie Road, about 3 miles east of Montana Highway 7. The tornado travelled north to County Road 616 then northwest over Beaver Creek before lifting at the Fallon/Wibaux County border. The tornado destroyed a well built cattle shed, lifted up, twisted and moved a large irrigation pipe about 100 yards and sucked the water out of a section of Beaver Creek.
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.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 02:19 UTC | 03:10 UTC | Tornado Warning | BYZ |
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. The outlook in force was issued at 00:34 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.
Glasgow Intl Airport, MT (KGGW), 00:00Z
2.0 hours before the tornado, 255 km from the path. June 21, 1999.
- Mixed-layer CAPE
- 250 J/kg
- Mixed-layer CIN
- -33 J/kg
- Surface CAPE
- 801 J/kg
- Mixed-layer LCL
- 2259 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- 45 m²/s²
- 0-3 km storm-relative helicity
- 90 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
- 0-3 km lapse rate
- 8.6 K/km
Glasgow Intl Airport, MT (KGGW), 12:00Z
10.0 hours after it, 255 km from the path. June 21, 1999.
- Mixed-layer CAPE
- 156 J/kg
- Mixed-layer CIN
- -364 J/kg
- Surface CAPE
- 379 J/kg
- Mixed-layer LCL
- 1949 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 370 m²/s²
- 0-3 km storm-relative helicity
- 317 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 4.1 K/km
The surface observations
Baker (BHK), 26 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:53 UTC | 82 | 70 | 140° 20 kt | 28 | ||
| 01:53 UTC | 79 | 68 | 170° 11 kt | |||
| 02:53 UTC | 77 | 68 | 180° 5 kt | |||
| 03:29 UTC | 73.4 | 60.8 | 60° 20 kt | 26 | ||
| 03:53 UTC | 70 | 62 | 80° 17 kt | 24 |
From the Iowa Environmental Mesonet's archive of airport observations.
This ground now
The live radar over the trackEvery 1999 tornado in MontanaEvery tornado in Montana since 1950Warnings in force in Montana nowThe forecast where you are
The other tornadoes of June 20, 1999
4 more were confirmed in the United States that day.
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.