Tornadoes · United States · Montana · 1988

F3 tornado, Chouteau County, Montana, July 5, 1988

This F3 tornado ran 10.0 miles across Chouteau County on July 5, 1988, touching down at 5:45 PM MDT and reaching 200 yards wide. It killed nobody, and did $500 to $5,000 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 mph

    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 mphthis tornado

    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
F3
Date
July 5, 1988
Touchdown
5:45 PM MDT (23:45 UTC)
Path length
10.0 miles (16.1 km)
Path width
200 yards (183 m)
Deaths
0
Injuries
0
Property damage
$500 to $5,000
County
Chouteau County
Touchdown point
47.870, -109.920
Lift-off point
47.950, -109.770
Record number
310

The warnings

3 minutes of warning. NWS TFX issued a tornado warning for this county at 23:42 UTC, 3 minutes before the tornado touched down, in force until 00:15 UTC.

Issued (UTC)ExpiredProductOffice
20:58 UTC22:00 UTCSevere Thunderstorm WarningTFX
22:01 UTC22:45 UTCSevere Thunderstorm WarningTFX
23:13 UTC00:15 UTCSevere Thunderstorm WarningTFX
23:42 UTC00:15 UTCTornado WarningTFX

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 06:24 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.

Great_falls, MT (KTFX), 12:00Z

11.8 hours before the tornado, 75 km from the path. July 5, 1988.

Skew-T log-pSkew-T log-p diagram, Great_falls, MT at 12:00Z on 1988-07-05Temperature 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 -77466, lifted condensation level 3665 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, Great_falls, MT at 12:00Z on 1988-07-05The 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 109 square meters per square second, 0 to 6 km bulk shear 48 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
-77466 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
3665 m above ground
0-6 km bulk shear
48 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
109 m²/s²
0-3 km storm-relative helicity
154 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.8 K/km

Open this sounding in Storm Lab

Great_falls, MT (KTFX), 00:00Z

0.2 hours after it, 75 km from the path. July 6, 1988.

Skew-T log-pSkew-T log-p diagram, Great_falls, MT at 00:00Z on 1988-07-06Temperature 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 -88861, lifted condensation level 3630 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, Great_falls, MT at 00:00Z on 1988-07-06The 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 -132 square meters per square second, 0 to 6 km bulk shear 49 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
-88861 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
3630 m above ground
0-6 km bulk shear
49 kt
0-1 km bulk shear
29 kt
0-1 km storm-relative helicity
-132 m²/s²
0-3 km storm-relative helicity
-39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

The surface observations

Havre (HVR), 71 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:00 UTC7963310° 10 kt1003TS
23:00 UTC6962290° 35 kt1003+TSRA
00:00 UTC6461300° 5 kt1005.1TSRA
01:00 UTC6759320° 11 kt1007.1-SHRA

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

This ground now

The live radar over the trackEvery 1988 tornado in MontanaEvery tornado in Montana since 1950Warnings in force in Montana nowThe forecast where you are

The other tornadoes of July 5, 1988

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 55:57 PM CDTF0Cavalier, ND0.213
July 56:17 PM CDTF0Cavalier, ND0.213
July 55:30 PM MDTF3Chouteau, MT3.02002$50,000 to $500,000
July 55:45 PM MDTF3Chouteau, MT12.0200$5,000 to $50,000
July 56:00 PM MDTF1Cascade, MT0.210$5,000 to $50,000
July 56:40 PM MDTF0Chouteau, MT0.210
July 58:50 PM CDTF0Barnes, ND0.210$5,000 to $50,000
July 59:30 PM MDTF0Valley, MT0.210
July 59:30 PM MDTF0Valley, MT0.210
July 59:30 PM MDTF0Valley, MT0.210
July 59:30 PM MDTF0Valley, MT0.210
July 59:30 PM MDTF0Valley, MT0.210
July 511:00 PM MDTF0Sheridan, MT0.210

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.