Tornadoes · United States · Florida · 2008

EF0 tornado, Sugarloaf Key, Florida, September 17, 2008

This EF0 tornado ran 0.0 miles across Monroe County on September 17, 2008, touching down at 12:40 PM EDT and reaching 20 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
September 17, 2008
Touchdown
12:40 PM EDT (16:40 UTC)
Path length
0.0 miles (0.0 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
Monroe County
Touchdown point
24.618, -81.592
Lift-off point
24.618, -81.592
Record number
0809171040-01

What the Weather Service recorded

A waterspout over Lower Sugarloaf Channel moved west and made landfall at a residential property in Bay Point.

A waterspout moved ashore along Bay Drive in Bay Point, overturning potted plants and trash cans.

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 forecast that day

The Storm Prediction Center had this point in a General Thunderstorms Risk. The outlook in force was issued at 16:11 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.

Key West, FL (KEYW), 12:00Z

4.7 hours before the tornado, 14 km from the path. September 17, 2008.

Skew-T log-pSkew-T log-p diagram, Key West, FL at 12:00Z on 2008-09-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1828 joules per kilogram, CIN -4, lifted condensation level 759 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, Key West, FL at 12:00Z on 2008-09-17The 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 1 square meters per square second, 0 to 6 km bulk shear 9 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
1828 J/kg
Mixed-layer CIN
-4 J/kg
Surface CAPE
2229 J/kg
Mixed-layer LCL
759 m above ground
0-6 km bulk shear
9 kt
0-1 km bulk shear
1 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
-29 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.1 K/km

Open this sounding in Storm Lab

Key West, FL (KEYW), 00:00Z

7.3 hours after it, 14 km from the path. September 18, 2008.

Skew-T log-pSkew-T log-p diagram, Key West, FL at 00:00Z on 2008-09-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2352 joules per kilogram, CIN -7, lifted condensation level 811 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, Key West, FL at 00:00Z on 2008-09-18The 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 -30 square meters per square second, 0 to 6 km bulk shear 6 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
2352 J/kg
Mixed-layer CIN
-7 J/kg
Surface CAPE
2676 J/kg
Mixed-layer LCL
811 m above ground
0-6 km bulk shear
6 kt
0-1 km bulk shear
7 kt
0-1 km storm-relative helicity
-30 m²/s²
0-3 km storm-relative helicity
-4 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.1 K/km

Open this sounding in Storm Lab

The surface observations

Key West Nas (NQX), 11 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
14:53 UTC86.3676110° 4 kt1015.6
15:53 UTC86.547680° 5 kt1015.6
16:42 UTC8675.2350° 5 kt1015.6-RA
16:53 UTC86.187620° 3 kt1015.2
17:02 UTC8675.20° 0 kt1015.2VCTS -RA
17:16 UTC8675.230° 9 kt1015.2-TSRA
17:20 UTC8675.240° 5 kt1015.2-TSRA
17:43 UTC8675.20° 0 kt1015.2-TSRA
17:53 UTC86.1876330° 3 kt1015.2-TSRA

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

The radar

The Key West radar (KBYX), 11 km away, was scanning. The volume nearest the touchdown began at 16:39 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
16:36 UTCWATER SPOUTNne Bay PointLower Keys In Monr, FLA TRAINED SPOTTER OBSERVED A WATERSPOUT OVER LOWER SUGARLOAF CHANNEL SOUTH OF MILE MARKER 17. DURATION 2 MINUTES. THE WATERSPOUT APPARENTLY MOVED WESTWARD AND MADE LANDFALL AS A WEAK TORNADO AT BAY POINT BEFORE QUICKLY D
16:38 UTCTORNADONne Bay PointLower Keys In Monr, FLA WATERSPOUT MOVED WEST FROM LOWER SUGARLOAF CHANNEL TO BAY POINT...QUICKLY DISSIPATING AFTER TURNING OVER POTTED PLANTS AND TRASH CANS NEAR ONE HOME ON BAY DRIVE.

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

This ground now

The live radar over the trackEvery 2008 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.