Tornadoes · United States · Oregon · 2018

EF0 tornado, Forest Grove, Oregon, October 29, 2018

This EF0 tornado ran 0.1 miles across Washington County on October 29, 2018, touching down at 2:17 PM PDT and reaching 20 yards wide. It killed nobody, and did $100,000 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 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
October 29, 2018
Touchdown
2:17 PM PDT (21:17 UTC)
Lifted
2:18 PM PDT (21:18 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.1 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
Property damage
$100,000
County
Washington County
Touchdown point
45.559, -123.139
Lift-off point
45.558, -123.137
Record number
1810291517-01

What the Weather Service recorded

A cold front which moved through on October 27th brought a much cooler air mass in aloft, which destabilized the atmosphere enough for thunderstorm development across the area on the 28th and 29th. There was enough vertical shear in the environment for a few of theses vigorous showers and thunderstorms to start to rotate, three of which went on to produce tornadoes.

Multiple greenhouse structures were damaged at a farm on Thatcher Road. Witness accounts also confirmed a tornado. The tornado was likely on the ground for about 30 seconds to 1 minute.

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.

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 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.

Salem/Mcnary, OR (KSLE), 12:00Z

9.3 hours before the tornado, 72 km from the path. October 29, 2018.

Skew-T log-pSkew-T log-p diagram, Salem/Mcnary, OR at 12:00Z on 2018-10-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3 joules per kilogram, CIN -4, lifted condensation level 483 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, Salem/Mcnary, OR at 12:00Z on 2018-10-29The 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 67 square meters per square second, 0 to 6 km bulk shear 32 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
3 J/kg
Mixed-layer CIN
-4 J/kg
Surface CAPE
9 J/kg
Mixed-layer LCL
483 m above ground
0-6 km bulk shear
32 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
67 m²/s²
0-3 km storm-relative helicity
73 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.9 K/km

Open this sounding in Storm Lab

Salem/Mcnary, OR (KSLE), 00:00Z

2.7 hours after it, 72 km from the path. October 30, 2018.

Skew-T log-pSkew-T log-p diagram, Salem/Mcnary, OR at 00:00Z on 2018-10-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 98 joules per kilogram, CIN -3, lifted condensation level 1009 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, Salem/Mcnary, OR at 00:00Z on 2018-10-30The 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 59 square meters per square second, 0 to 6 km bulk shear 52 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
98 J/kg
Mixed-layer CIN
-3 J/kg
Surface CAPE
531 J/kg
Mixed-layer LCL
1009 m above ground
0-6 km bulk shear
52 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
81 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.5 K/km

Open this sounding in Storm Lab

The surface observations

Portland/Hillsboro (HIO), 15 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
19:20 UTC210° 6 kt1023.7
19:25 UTC190° 5 kt1023.7
19:30 UTC200° 7 kt1023.7
19:35 UTC210° 7 kt1023.7
19:40 UTC200° 6 kt1023.7
19:45 UTC210° 8 kt1023.7
19:50 UTC220° 6 kt1023.7
19:53 UTC5750 4 kt1023.7
19:55 UTC220° 6 kt1023.7
20:00 UTC200° 5 kt1023.7
20:05 UTC230° 5 kt1023.7
20:10 UTC200° 7 kt1023.7
20:15 UTC180° 7 kt1023.7
20:20 UTC220° 5 kt1023.7
20:25 UTC240° 6 kt1023.7
20:30 UTC210° 5 kt1023.7
20:35 UTC220° 6 kt1023.7
20:40 UTC210° 6 kt1023.7
20:45 UTC200° 4 kt1023.7
20:50 UTC200° 6 kt1023.7-RA
20:53 UTC5748210° 4 kt1023.7-RA
20:55 UTC240° 4 kt1023.7-RA
21:00 UTC210° 5 kt1023.7
21:05 UTC230° 4 kt1023.7-RA
21:10 UTC240° 5 kt1023.7-RA
21:15 UTC170° 5 kt1023.7-RA
21:20 UTC160° 7 kt1023.7
21:25 UTC200° 5 kt1023.4
21:30 UTC170° 6 kt1023.7
21:35 UTC190° 8 kt1023.7
21:40 UTC160° 8 kt1023.4-RA
21:45 UTC170° 7 kt1023.4-RA
21:50 UTC190° 5 kt1023.7-RA
21:53 UTC5750260° 6 kt1023.7-RA
21:55 UTC290° 5 kt1023.7-RA
22:00 UTC30° 4 kt1023.7+RA
22:05 UTC350° 4 kt1023.7+RA
22:10 UTC60° 4 kt1023.7+RA
22:15 UTC80° 4 kt1023.7-RA
22:20 UTC0° 0 kt1023.7-RA
22:25 UTC0° 0 kt1023.7
22:30 UTC0° 0 kt1023.7
22:35 UTC0° 0 kt1024
22:40 UTC0° 0 kt1024
22:45 UTC0° 0 kt1024
22:50 UTC0° 0 kt1024
22:53 UTC54510° 0 kt1024
22:55 UTC0° 0 kt1024
23:00 UTC0° 0 kt1024
23:05 UTC0° 0 kt1024
23:10 UTC70° 3 kt1024
23:15 UTC0° 0 kt1024

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

The radar

The Portland,OR radar (KRTX), 22 km away, was scanning. The volume nearest the touchdown began at 21:14 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
21:17 UTCFUNNEL CLOUD3 Nnw Forest GroveWashington, ORMULTIPLE REPORTS OF A FUNNEL CLOUD WERE REPORTED NORTH OF FOREST GROVE. SOME REPORTS INDICATED A POSSIBLE TORNADO TOUCHDOWN. DUE TO NIGHTFALL, NWS EMPLOYEES WILL DO A SURVEY TUESDAY MORNING. THE TIME HAS BEEN CORRECTED F
21:17 UTCTORNADO 03 Nnw Forest GroveWashington, ORNWS STORM SURVEY TEAM HAS CONFIRMED A WEAK TORNADO, RATED EF-0, BRIEFLY OCCURRED ON OCTOBER 29 AROUND 217 PM. DAMAGE TO SEVERAL GREENHOUSE STRUCTURES AT A FARM ALONG KEMPER RD WAS CONSISTENT WITH TORNADO DAMAGE. TORNADO
22:00 UTCFUNNEL CLOUD2 N Forest GroveWashington, ORA FUNNEL CLOUD WAS REPORTED VIA SOCIAL MEDIA BY THE PUBLIC NEAR FOREST GROVE. TIME AND LOCATION IS ESTIMATED VIA RADAR AND THE PUBLIC REPORT.

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

This ground now

The live radar over the trackEvery 2018 tornado in OregonEvery tornado in Oregon since 1950Warnings in force in Oregon nowThe forecast where you are

The other tornadoes of October 29, 2018

4 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
October 297:35 AM EDTEF1Suffolk, NY2.0100$50,000
October 297:58 AM EDTEF0Southeastern Connecticut Planning Region, CT2.3100$50,000
October 299:58 AM EDTEF0Barnstable, MA0.110$300
October 293:30 PM PDTEF0Marion, OR0.110$200

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.