Tornadoes · United States · Minnesota · 2017

EF0 tornado, Brandon to Carlos, Minnesota, July 17, 2017

From Brandon to Carlos, this EF0 tornado ran 4.7 miles across Douglas County on July 17, 2017, touching down at 6:07 PM CDT and reaching 200 yards wide. It killed nobody.

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 mphthis tornado

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

  2. EF186 to 110 mph

    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
EF0
Date
July 17, 2017
Touchdown
6:07 PM CDT (23:07 UTC)
Lifted
6:16 PM CDT (23:16 UTC)
On the ground
9 minutes
Path length
4.7 miles (7.5 km)
Path width
200 yards (183 m)
Deaths
0
Injuries
0
County
Douglas County
Touchdown point
45.981, -95.376
Lift-off point
45.995, -95.281
Record number
1707171707-01

The damage survey

17 damage points were recorded along this path by NWS MPX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 75 mph.

  • Numerous trees down. Definite convergent pattern.
  • Tree down from south to north. Beginning of tornado just west of here.
  • definitely convergent. Tree on northern end was downed from north to south. Tornado began just west of here.
  • mostly to n or ne. southern edge of circulation

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

What the Weather Service recorded

There were several reports of trees and branches that were blown down, which turned out to be associated with tornadoes and associated rear flank downdraft winds. Carlos Creek Winery was among the areas hit. The storm also produced large hail and heavy rain, including 3.2 inches of rainfall near Brandon. Power outages also occurred. At the height of the storm, about 950 Runestone Electric Association members were without electricity.

The tornado knocked down a few dozen trees, but there was no structural damage.

Hundreds of trees were uprooted or broken near Lake Carlos. Some trees fell on power lines. No structural damage was noted or reported.

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

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Twin Cities, MN wrote its last area forecast discussion before the tornado touched down at Jul 17, 4:11 PM CDT, 1 hour 56 minutes earlier.

Area forecast discussion, Jul 17, 4:11 PM CDT, 1 hour 56 minutes before
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Hazardous weather outlook, Jul 17, 3:21 PM CDT, 2 hours 46 minutes before
Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
321 PM CDT Mon Jul 17 2017

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
182030-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-
Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington-
Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota-
Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth-
Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk-
St. Croix-Pierce-Dunn-Pepin-Eau Claire-
321 PM CDT Mon Jul 17 2017

This Hazardous Weather Outlook is for portions of central and
southern Minnesota...and west central Wisconsin.

.DAY ONE...This Afternoon and Tonight

There is a slight risk of severe thunderstorms over parts of
central Minnesota into tonight. Large hail and damaging winds
would be the main threat.

Heat indices of near 100 to 105 degrees will continue through the
afternoon for much of Minnesota.this afternoon. People who are
active outdoors will need to remember to stay hydrated and take
breaks in the shade as needed.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

There is a slight risk of severe thunderstorms for much of
southern Minnesota and west central Wisconsin for Tuesday and
Tuesday night. The risk for severe storms remains into Wednesday
night as well. Along with damaging winds and large hail,
excessive rainfall is also a possibility, especially across
southern Minnesota Tuesday into Wednesday night. Thunderstorm
chances will finally end Sunday.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed across central Minnesota
this evening.

In the hours before

Local storm report, Jul 17, 5:48 PM CDT, 19 minutes before
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Local storm report, Jul 17, 5:49 PM CDT, 18 minutes before
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Local storm report, Jul 17, 6:04 PM CDT, 3 minutes before
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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.

Minneapolis, MN (KMPX), 12:00Z

11.1 hours before the tornado, 185 km from the path. July 17, 2017.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2017-07-17Temperature 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 -57917, lifted condensation level 1041 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, Minneapolis, MN at 12:00Z on 2017-07-17The 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 140 square meters per square second, 0 to 6 km bulk shear 27 knots.1939Sfc1 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
-57917 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1041 m above ground
0-6 km bulk shear
27 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
214 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
2.9 K/km

Open this sounding in Storm Lab

Minneapolis, MN (KMPX), 00:00Z

0.9 hours after it, 185 km from the path. July 18, 2017.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2017-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3117 joules per kilogram, CIN -3, lifted condensation level 998 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 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, Minneapolis, MN at 00:00Z on 2017-07-18The 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 100 square meters per square second, 0 to 6 km bulk shear 41 knots.193958Sfc1 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
3117 J/kg
Mixed-layer CIN
-3 J/kg
Surface CAPE
4617 J/kg
Mixed-layer LCL
998 m above ground
0-6 km bulk shear
41 kt
0-1 km bulk shear
16 kt
0-1 km storm-relative helicity
100 m²/s²
0-3 km storm-relative helicity
191 m²/s²
Significant tornado parameter
2.0
Supercell composite
13.1
0-3 km lapse rate
7.3 K/km

Open this sounding in Storm Lab

The surface observations

Alexandria (AXN), 14 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:00 UTC

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

The radar

The Minneapolis radar (KMPX), 187 km away, was scanning. The volume nearest the touchdown began at 23:07 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.

This ground now

The live radar over the trackEvery 2017 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

The other tornadoes of July 17, 2017

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 175:39 PM CDTEF0Todd, MN4.4200
July 175:46 PM CDTEF0Douglas, MN1.975

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.