Tornadoes · United States · Florida · 2017

EF0 tornado, Apalachicola, Florida, June 20, 2017

This EF0 tornado ran 0.4 miles across Franklin County on June 20, 2017, touching down at 10:15 AM EDT and reaching 50 yards wide. It killed nobody, and did $10,000 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
June 20, 2017
Touchdown
10:15 AM EDT (14:15 UTC)
Lifted
10:20 AM EDT (14:20 UTC)
On the ground
5 minutes
Path length
0.4 miles (0.6 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$10,000
County
Franklin County
Touchdown point
29.639, -84.908
Lift-off point
29.645, -84.909
Record number
1706200815-01

The damage survey

5 damage points were recorded along this path by NWS TAE, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 85 mph.

  • Several small pine trees snapped or uprooted.
  • Minor metal roof damage to well-build coastal home.
  • Minor roof damage to newer coastal home.
  • Minor metal roof damage to newer coastal home.

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

On the morning of June 20, a low-topped supercell associated with a tropical disturbance (future Tropical Storm Cindy) moved across the western portion of St. George Island. The cell produced a weak tornado as it crossed the island.

A tornadic waterspout moved onshore western portion of St. George Island, causing minor tree damage and minor roof damage to 3 well-built coastal homes. Video on social media confirms that the tornado was on the ground as it crossed the beach. Damage was supportive of high end EF0 rating with max winds estimated near 85 mph. The survey was conducted with help and data from Franklin County Emergency Management.

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
03:00 UTC00:00 UTCSmall Craft AdvisoryTAE
13:30 UTC14:30 UTCMarine WarningTAE
13:47 UTC14:45 UTCMarine WarningTAE
14:36 UTC15:30 UTCMarine WarningTAE
15:26 UTC17:00 UTCMarine WarningTAE
03:00 UTC05:00 UTCMarine WarningTAE
03:24 UTC15:00 UTCTornado WatchTAE
04:55 UTC05:53 UTCMarine WarningTAE

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 General Thunderstorms Risk. The outlook in force was issued at 12:58 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.

Tallahassee Rgnl, FL (KTLH), 12:00Z

2.3 hours before the tornado, 103 km from the path. June 20, 2017.

Skew-T log-pSkew-T log-p diagram, Tallahassee Rgnl, FL at 12:00Z on 2017-06-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 110 joules per kilogram, CIN -17, lifted condensation level 580 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, Tallahassee Rgnl, FL at 12:00Z on 2017-06-20The 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 88 square meters per square second, 0 to 6 km bulk shear 23 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
110 J/kg
Mixed-layer CIN
-17 J/kg
Surface CAPE
322 J/kg
Mixed-layer LCL
580 m above ground
0-6 km bulk shear
23 kt
0-1 km bulk shear
13 kt
0-1 km storm-relative helicity
88 m²/s²
0-3 km storm-relative helicity
130 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.1 K/km

Open this sounding in Storm Lab

Tallahassee Rgnl, FL (KTLH), 00:00Z

9.7 hours after it, 103 km from the path. June 21, 2017.

Skew-T log-pSkew-T log-p diagram, Tallahassee Rgnl, FL at 00:00Z on 2017-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 439 joules per kilogram, CIN -17, lifted condensation level 713 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, Tallahassee Rgnl, FL at 00:00Z on 2017-06-21The 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 173 square meters per square second, 0 to 6 km bulk shear 35 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
439 J/kg
Mixed-layer CIN
-17 J/kg
Surface CAPE
1666 J/kg
Mixed-layer LCL
713 m above ground
0-6 km bulk shear
35 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
173 m²/s²
0-3 km storm-relative helicity
249 m²/s²
Significant tornado parameter
0.3
Supercell composite
4.8
0-3 km lapse rate
6.0 K/km

Open this sounding in Storm Lab

The surface observations

Apalachicola Municipal (Asos) (AAF), 15 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
12:53 UTC757550° 7 kt1015.6+RA BR
13:09 UTC757550° 7 kt1015.6RA BR
13:53 UTC757550° 7 kt1015.6RA BR
14:05 UTC757590° 4 kt1015.9+RA BR
14:15 UTC747420° 6 kt1015.9+RA BR
14:24 UTC740° 0 kt1015.9+RA
14:37 UTC747450° 4 kt1016.3+RA FG
14:53 UTC7474290° 13 kt1015.9+RA BR
14:57 UTC7474320° 10 kt1015.9+RA BR
15:02 UTC74740° 0 kt1015.9+RA BR
15:24 UTC73.473.40° 0 kt1016.3+RA FG
15:34 UTC747430° 13 kt1016.3+RA BR
15:38 UTC73.473.420° 9 kt1016.3+RA BR
15:53 UTC747420° 7 kt1016.3+RA BR
15:57 UTC747430° 7 kt1016.3RA BR
16:05 UTC 1016.3RA BR

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

The radar

The Tallahassee radar (KTLH), 101 km away, was scanning. The volume nearest the touchdown began at 14:12 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
14:15 UTCTORNADO3 Wsw St George IslandFranklin, FLTORNADO MOVED ONSHORE WESTERN PORTION OF ST. GEORGE ISLAND, CAUSING MINOR DAMAGE TO TREES AND THREE HOMES. VIDEO CONFIRMED TORNADO WAS ON GROUND AS IT CROSSED THE BEACH. DAMAGE CONSISTENT WITH HIGH-END EF0 RATING AND MAX

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 FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

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.