Tornadoes · United States · Florida · 2010

EF0 tornado, Key Largo Pt Arpt, Florida, August 30, 2010

This EF0 tornado ran 0.1 miles across Monroe County on August 30, 2010, touching down at 7:10 PM EDT and reaching 15 yards wide. It killed nobody, and did $500 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 30, 2010
Touchdown
7:10 PM EDT (23:10 UTC)
Path length
0.1 miles (0.2 km)
Path width
15 yards (14 m)
Deaths
0
Injuries
0
Property damage
$500
County
Monroe County
Touchdown point
25.090, -80.431
Lift-off point
25.090, -80.431
Record number
1008301710-01

What the Weather Service recorded

A waterspout moved ashore as a weak tornado in Key Largo. Very minor damage occurred near the immediate shore.

A retired air traffic controller observed a waterspout moving onshore from the Atlantic waters in the Winston Waterways section of Key Largo. A few tree branches were downed with some patio furniture tossed about. A minor power outage occurred nearby to 5 customers. The duration was only a few seconds with path length around 400 feet. Maximum winds were estimated between 50 to 60 mph.

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 19:35 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.

Miami, FL (KMFL), 12:00Z

11.2 hours before the tornado, 82 km from the path. August 30, 2010.

Skew-T log-pSkew-T log-p diagram, Miami, FL at 12:00Z on 2010-08-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2910 joules per kilogram, CIN 0, lifted condensation level 555 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Miami, FL at 12:00Z on 2010-08-30The 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 -43 square meters per square second, 0 to 6 km bulk shear 7 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
2910 J/kg
Mixed-layer CIN
0 J/kg
Surface CAPE
3276 J/kg
Mixed-layer LCL
555 m above ground
0-6 km bulk shear
7 kt
0-1 km bulk shear
12 kt
0-1 km storm-relative helicity
-43 m²/s²
0-3 km storm-relative helicity
15 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

Miami, FL (KMFL), 00:00Z

0.8 hours after it, 82 km from the path. August 31, 2010.

Skew-T log-pSkew-T log-p diagram, Miami, FL at 00:00Z on 2010-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1650 joules per kilogram, CIN -5, lifted condensation level 599 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Miami, FL at 00:00Z on 2010-08-31The 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 43 square meters per square second, 0 to 6 km bulk shear 21 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
1650 J/kg
Mixed-layer CIN
-5 J/kg
Surface CAPE
2484 J/kg
Mixed-layer LCL
599 m above ground
0-6 km bulk shear
21 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
6 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.4 K/km

Open this sounding in Storm Lab

The surface observations

Homestead Afb (HST), 45 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
21:13 UTC867770° 10 kt1016.3VCTS
21:15 UTC867770° 11 kt1016.3TS
21:17 UTC867770° 8 kt1016.6TS
21:27 UTC84.275.270° 19 kt1016.6-TSRA
21:28 UTC84.275.270° 18 kt241016.6-TSRA
21:32 UTC80.675.270° 12 kt241016.9TSRA
21:34 UTC80.675.270° 10 kt241016.9+TSRA
21:37 UTC78.875.280° 9 kt1016.9+TSRA BR
21:39 UTC78.875.2100° 7 kt1016.9TSRA BR
21:41 UTC78.875.2100° 6 kt1016.6-RA BR
21:48 UTC7775.270° 6 kt1016.6RA
21:49 UTC7775.260° 6 kt1016.6RA BR
21:55 UTC77.3674.6660° 6 kt1016.6RA BR
22:00 UTC7775.250° 4 kt1016.6-RA
22:04 UTC7775.240° 5 kt1016.6-RA
22:07 UTC7775.240° 4 kt1016.6RA
22:13 UTC7775.240° 4 kt1016.6-RA
22:16 UTC78.875.240° 4 kt1016.6-RA
22:19 UTC78.875.240° 3 kt1016.6-RA
22:23 UTC78.875.20° 0 kt1016.6
22:55 UTC79.77670° 12 kt161016.9-RA
23:02 UTC78.875.2100° 10 kt161016.9RA BR
23:04 UTC7775.2110° 6 kt161016.9RA BR
23:08 UTC7775.2100° 7 kt161016.9-RA BR
23:14 UTC78.87790° 8 kt1016.9
23:17 UTC78.87790° 8 kt1016.9-RA
23:31 UTC7775.2100° 10 kt1016.9+RA BR
23:34 UTC7775.2100° 9 kt1016.9+RA BR
23:36 UTC7775.2100° 11 kt1017.3+RA BR
23:38 UTC7775.290° 11 kt1017.3+RA BR
23:40 UTC7775.290° 12 kt171017.3+RA BR
23:42 UTC7775.290° 10 kt171017.3RA BR
23:44 UTC7775.290° 8 kt171017.3RA BR
23:47 UTC7775.290° 7 kt171017.3-RA BR
23:49 UTC7775.290° 6 kt1017.3-RA BR
23:55 UTC77.3675.3890° 6 kt1017.3-RA BR
00:06 UTC7775.2100° 10 kt1017.3VCTS -RA
00:09 UTC7775.2100° 9 kt1017.6VCTS RA BR
00:13 UTC7775.2100° 10 kt1017.6VCTS RA BR
00:34 UTC7775.2120° 9 kt141017.6-RA BR
00:36 UTC7775.2130° 10 kt141017.3+RA BR
00:38 UTC7775.2130° 11 kt1017.3+RA BR
00:41 UTC75.273.4140° 10 kt1017.3+RA BR
00:42 UTC75.273.4130° 8 kt1017.3+RA BR
00:47 UTC75.273.4130° 9 kt1017.3-RA BR
00:55 UTC75.7474140° 5 kt1017.3+RA BR
01:02 UTC75.275.2140° 3 kt1017.3-RA
01:03 UTC75.275.2130° 3 kt1017.3

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

The radar

The Miami radar (KAMX), 58 km away, was scanning. The volume nearest the touchdown began at 23:08 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 2010 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

The other tornadoes of August 30, 2010

1 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 301:51 PM MDTEF1Washakie, WY4.530$70,000

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.