Tornadoes · United States · Montana · 2007

EF1 tornado, Malta, Montana, August 10, 2007

This EF1 tornado ran 0.1 miles across Phillips County on August 10, 2007, touching down at 6:15 PM MDT and reaching 10 yards wide. It killed nobody, and did $25,000 of property damage.

The rating scale

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

  1. EF065 to 85 mph

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

  2. EF186 to 110 mphthis tornado

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

  3. EF2111 to 135 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. EF3136 to 165 mph

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

  5. EF4166 to 200 mph

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

  6. EF5over 200 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
EF1
Date
August 10, 2007
Touchdown
6:15 PM MDT (00:15 UTC)
Lifted
6:21 PM MDT (00:21 UTC)
On the ground
6 minutes
Path length
0.1 miles (0.2 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
Property damage
$25,000
County
Phillips County
Touchdown point
48.207, -107.655
Lift-off point
48.207, -107.655
Record number
0708101815-01

What the Weather Service recorded

A vigorous upper level storm system and strong cold front produced a widespread severe weather outbreak in northeastern Montana. The majority of the events were high wind, a few reports of large hail, and two tornadoes.

Several outbuildings on the property were leaning to the east, and shingles were found at least 100 yards away. A refrigerator was flipped off the front porch of a house, and water was sucked up out of a four foot tall pool in the back yard. A windmill was also twisted and a steer barn collapsed. Based on the NWS damage survey the damage was estimated as EF1 where the steer barn collapsed, and the remainder of the damage was estimated at EF0.

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

The warnings

18 minutes of warning. NWS GGW issued a tornado warning for this county at 23:57 UTC, 18 minutes before the tornado touched down, in force until 01:00 UTC.

The county was under a severe thunderstorm watch, issued at 22:45 UTC and running to 04:44 UTC.

Issued (UTC)ExpiredProductOffice
18:00 UTC10:16 UTCFire Weather WatchGGW
18:00 UTC06:00 UTCRed Flag WarningGGW
22:45 UTC04:44 UTCSevere Thunderstorm WatchGGW
23:16 UTC23:45 UTCSevere Thunderstorm WarningGGW
23:44 UTC00:15 UTCSevere Thunderstorm WarningGGW
23:50 UTC00:45 UTCSevere Thunderstorm WarningGGW
23:57 UTC01:00 UTCTornado WarningGGW
00:14 UTC01:00 UTCSevere Thunderstorm WarningGGW
00:29 UTC00:57 UTCSevere Thunderstorm WarningGGW
00:37 UTC01:00 UTCSevere Thunderstorm WarningGGW

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 20:01 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

0.3 hours before the tornado, 78 km from the path. August 11, 2007.

Skew-T log-pSkew-T log-p diagram, Glasgow Intl Airport, MT at 00:00Z on 2007-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 49 joules per kilogram, CIN -240, lifted condensation level 3080 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 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, Glasgow Intl Airport, MT at 00:00Z on 2007-08-11The 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 -3 square meters per square second, 0 to 6 km bulk shear 57 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
49 J/kg
Mixed-layer CIN
-240 J/kg
Surface CAPE
650 J/kg
Mixed-layer LCL
3080 m above ground
0-6 km bulk shear
57 kt
0-1 km bulk shear
4 kt
0-1 km storm-relative helicity
-3 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1
0-3 km lapse rate
8.5 K/km

Open this sounding in Storm Lab

Glasgow Intl Airport, MT (KGGW), 12:00Z

11.7 hours after it, 78 km from the path. August 11, 2007.

Skew-T log-pSkew-T log-p diagram, Glasgow Intl Airport, MT at 12:00Z on 2007-08-11Temperature 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 -80257, lifted condensation level 1071 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, Glasgow Intl Airport, MT at 12:00Z on 2007-08-11The 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 -182 square meters per square second, 0 to 6 km bulk shear 52 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
-80257 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1071 m above ground
0-6 km bulk shear
52 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
-182 m²/s²
0-3 km storm-relative helicity
-77 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.0 K/km

Open this sounding in Storm Lab

The surface observations

Glasgow International Airport (GGW), 77 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:53 UTC8949350° 7 kt1006.8
23:53 UTC8747320° 3 kt1006.8
00:53 UTC8349280° 11 kt1008.5
01:04 UTC73.446.4280° 29 kt461009.1SQ
01:53 UTC6858150° 9 kt1011.5-RA

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

The radar

The Glasgow radar (KGGW), 76 km away, was scanning. The volume nearest the touchdown began at 00:12 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
00:00 UTCTSTM WND GST 704 Nne SacoPhillips, MTWIND THROWING ROCKS AGAINST HOUSES
00:10 UTCTSTM WND GST 608 E MaltaPhillips, MTCOTTONWOOD BRANCHES UP TO 4 INCHES IN DIAMETER SNAPPED OFF.
00:30 UTCTSTM WND GST 6046 Sw GlasgowValley, MT
00:35 UTCTSTM WND GST 606 N SacoPhillips, MT
00:35 UTCTSTM WND GST 704 Nne SacoPhillips, MTWIND BLOWING ROCKS INTO BUILDINGS
00:55 UTCTSTM WND GST 60HinsdaleValley, MT150 GALLON TANK WAS QUARTER FULL AND RAISED UP ON ITS SIDE FROM WIND GUST.
02:02 UTCTORNADO14 Se MaltaPhillips, MTOCCUPANT COULD NOT OPEN WINDOWS OR DOORS FROM INSIDE OF HOUSE. WATER SWIRLED UPWARD FROM POOL LOCATED NEXT TO HOUSE, POOL LOST 1-2 FEET OF WATER. BARN NOW LEANING TOWARD THE EAST. CAMPER TRAILER TURNED UPSIDE DOWN. WINDM

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

This ground now

The live radar over the trackEvery 2007 tornado in MontanaEvery tornado in Montana since 1950Warnings in force in Montana nowThe forecast where you are

The other tornadoes of August 10, 2007

7 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 102:18 PM CDTEF0Ramsey, ND1.525
August 102:30 PM CDTEF1Nelson, ND4.150
August 106:06 PM MDTEF0Corson, SD0.320
August 106:10 PM MDTEF0Corson, SD0.210
August 107:45 PM MDTEF1Valley, MT0.310$10,000
August 109:25 PM CDTEF0Walworth, SD0.110
August 1011:04 PM CDTEF0Williams, ND1.040

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.