Tornadoes · United States · Virginia · 2017

EF0 tornado, Weems to Irvington, Virginia, August 7, 2017

From Weems to Irvington, this EF0 tornado ran 2.1 miles across Lancaster County on August 7, 2017, touching down at 2:51 PM EDT and reaching 50 yards wide. It killed nobody, and did $15,000 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
August 7, 2017
Touchdown
2:51 PM EDT (18:51 UTC)
Lifted
2:55 PM EDT (18:55 UTC)
On the ground
4 minutes
Path length
2.1 miles (3.4 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$15,000
County
Lancaster County
Touchdown point
37.657, -76.450
Lift-off point
37.668, -76.415
Record number
1708071251-01

The damage survey

7 damage points were recorded along this path by NWS AKQ, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 63 mph.

  • End Point of visible damage

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

Scattered severe thunderstorms associated with low pressure and a cold front produced damaging winds, one tornado, and heavy rain across portions of central and eastern Virginia.

A weak tornado caused a few shingles and siding to be blown off a couple of homes, and trees were also blown down in the area.

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.

Issued (UTC)ExpiredProductOffice
16:00 UTC01:37 UTCFlash Flood WatchAKQ

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, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 16:30 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.

Wallops Is Stn, VA (KWAL), 12:00Z

6.9 hours before the tornado, 95 km from the path. August 7, 2017.

Skew-T log-pSkew-T log-p diagram, Wallops Is Stn, VA at 12:00Z on 2017-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 57 joules per kilogram, CIN -91, lifted condensation level 996 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, Wallops Is Stn, VA at 12:00Z on 2017-08-07The 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 176 square meters per square second, 0 to 6 km bulk shear 45 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
57 J/kg
Mixed-layer CIN
-91 J/kg
Surface CAPE
492 J/kg
Mixed-layer LCL
996 m above ground
0-6 km bulk shear
45 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
176 m²/s²
0-3 km storm-relative helicity
193 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3
0-3 km lapse rate
5.8 K/km

Open this sounding in Storm Lab

Wallops Is Stn, VA (KWAL), 00:00Z

5.1 hours after it, 95 km from the path. August 8, 2017.

Skew-T log-pSkew-T log-p diagram, Wallops Is Stn, VA at 00:00Z on 2017-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 700 joules per kilogram, CIN -22, lifted condensation level 784 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, Wallops Is Stn, VA at 00:00Z on 2017-08-08The 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 150 square meters per square second, 0 to 6 km bulk shear 33 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
700 J/kg
Mixed-layer CIN
-22 J/kg
Surface CAPE
1716 J/kg
Mixed-layer LCL
784 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
23 kt
0-1 km storm-relative helicity
150 m²/s²
0-3 km storm-relative helicity
202 m²/s²
Significant tornado parameter
0.4
Supercell composite
4.3
0-3 km lapse rate
5.2 K/km

Open this sounding in Storm Lab

The surface observations

Saluda Hummel Field (W75), 7 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
16:55 UTC77.476.8200° 7 kt1014.6
17:15 UTC7876.6200° 6 kt1013.9
17:35 UTC79.377200° 7 kt1013.9
17:55 UTC8076200° 6 kt1013.5
18:15 UTC79.775.6190° 6 kt1013.2
18:35 UTC80.676200° 8 kt1012.9
18:55 UTC81.576200° 11 kt171012.5
19:15 UTC82.476.3200° 13 kt191012.2
19:35 UTC8376210° 5 kt171011.9
19:55 UTC82.875.2230° 7 kt141011.9
20:15 UTC82.275.4210° 5 kt1011.5
20:35 UTC83.876230° 5 kt1011.2

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

The radar

The Norfolk radar (KAKQ), 91 km away, was scanning. The volume nearest the touchdown began at 18:49 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
18:59 UTCTSTM WND DMG1 Ene WeemsLancaster, VASOME SCATTERED TREES AND POWERLINES DOWNED IN THE IRVINGTON AND WEEMS AREA. PATIO FURNITURE AND POOL CANOPY DAMAGED. SOME SHINGLES AND SIDING DAMAGED ON HOMES, BUT NO STRUCTURAL DAMAGE.
19:37 UTCTSTM WND DMG1 E NassawadoxNorthampton, VALARGE BRANCHES, 1 TO 3 INCHES IN DIAMETER, BROKEN.
19:45 UTCFUNNEL CLOUDBirdsnestNorthampton, VAFUNNEL CLOUD SPOTTED NEAR BIRDSNEST, VA.
19:45 UTCTSTM WND DMGNassawadoxNorthampton, VATREE KNOCKED DOWN ALONG SEASIDE ROAD. TIME ESTIMATED FROM RADAR.
19:47 UTCTSTM WND DMG2 Ese Willis WharfAccomack, VALARGE BRANCHES, 1 TO 3 INCHES IN DIAMETER, BROKEN.

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

This ground now

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

The other tornadoes of August 7, 2017

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 71:40 PM EDTEF1Wicomico, MD1.5150$750,000
August 74:22 PM MDTEF0Chase, NE0.110

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.