Tornadoes · United States · Florida · 2004

F1 tornado, Green Cove Spgs, Florida, September 6, 2004

This F1 tornado ran 0.5 miles across Clay County on September 6, 2004, touching down at 6:45 PM EDT and reaching 75 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mphthis tornado

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 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. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 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
F1
Date
September 6, 2004
Touchdown
6:45 PM EDT (22:45 UTC)
Path length
0.5 miles (0.8 km)
Path width
75 yards (69 m)
Deaths
0
Injuries
0
County
Clay County
Touchdown point
30.000, -81.680
Lift-off point
30.000, -81.680
Record number
452

What the Weather Service recorded

Hurricane "Frances"NWS Storm Survey found 7 power boats, 6 sailboats and 1 houseboat destroyed and sunk by a F1 tornado. A 32 ft. boat was picked up and put on top of a houseboat on the other side of the pier. The tornado crossed Black Creek and entered the woods across U.S. highway 17 and damaged trees.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

6 minutes of warning. NWS JAX issued a tornado warning for this county at 22:39 UTC, 6 minutes before the tornado touched down, in force until 23:30 UTC.

Issued (UTC)ExpiredProductOffice
22:39 UTC23:30 UTCTornado WarningJAX
23:13 UTC00:00 UTCTornado WarningJAX
23:33 UTC00:00 UTCTornado WarningJAX
00:21 UTC01:00 UTCTornado WarningJAX

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 19:52 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.

Jacksonville, FL (KJAX), 12:00Z

10.8 hours before the tornado, 56 km from the path. September 6, 2004.

Skew-T log-pSkew-T log-p diagram, Jacksonville, FL at 12:00Z on 2004-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 830 joules per kilogram, CIN -4, lifted condensation level 653 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 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, Jacksonville, FL at 12:00Z on 2004-09-06The 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 235 square meters per square second, 0 to 6 km bulk shear 48 knots.19395878Sfc1 km3 km6 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
830 J/kg
Mixed-layer CIN
-4 J/kg
Surface CAPE
875 J/kg
Mixed-layer LCL
653 m above ground
0-6 km bulk shear
48 kt
0-1 km bulk shear
48 kt
0-1 km storm-relative helicity
235 m²/s²
0-3 km storm-relative helicity
235 m²/s²
Significant tornado parameter
1.1
Supercell composite
4.8
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

Jacksonville, FL (KJAX), 00:00Z

1.2 hours after it, 56 km from the path. September 7, 2004.

Skew-T log-pSkew-T log-p diagram, Jacksonville, FL at 00:00Z on 2004-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 307 joules per kilogram, CIN -7, lifted condensation level 785 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, Jacksonville, FL at 00:00Z on 2004-09-07The 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 19 square meters per square second, 0 to 6 km bulk shear 31 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
307 J/kg
Mixed-layer CIN
-7 J/kg
Surface CAPE
1302 J/kg
Mixed-layer LCL
785 m above ground
0-6 km bulk shear
31 kt
0-1 km bulk shear
5 kt
0-1 km storm-relative helicity
19 m²/s²
0-3 km storm-relative helicity
59 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3
0-3 km lapse rate
5.6 K/km

Open this sounding in Storm Lab

The surface observations

Jacksonville Nas (NIP), 26 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:55 UTC7971140° 19 kt261003.4-RA
21:55 UTC8071130° 25 kt341003-RA
22:55 UTC7874130° 18 kt311003.4-RABR
23:23 UTC7775150° 18 kt341003.4-RABR
23:55 UTC7775160° 17 kt311003.7RA BR

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

The radar

The Jacksonville radar (KJAX), 54 km away, was scanning. The volume nearest the touchdown began at 22:44 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
19:45 UTCTORNADO 1Green Cove SpringsClay, FL7 POWER BOATS...6 SAILBOATS..1 HOUSEBOAT...DESTROYED AND SUNK BY TORNADO. 32 FOOT BOAT PICKED UP AND PUT ON TOP OF HOUSEBOAT AND ACROSS PIER. TORNADO CROSSED BLACK CREEK AND ENTERED WOODS ACROSS US 17 DAMAGING TREES.
22:55 UTCFUNNEL CLOUDPalatkaPutnam, FLDEPUTY REPORTED FUNNEL CLOUD EAST OF STATE ROAD 19.
22:56 UTCFUNNEL CLOUDPalatkaPutnam, FLFIRE DEPARTMENT REPORTED FUNNEL CLOUD IN WESTERN SECTION OF TOWN.

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

This ground now

The live radar over the trackEvery 2004 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

The other tornadoes of September 6, 2004

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
September 62:15 AM EDTF0Saint Johns, FL1.075$60,000
September 63:30 AM EDTF0Bryan, GA0.530
September 64:20 AM EDTF0Bulloch, GA5.060
September 69:00 AM EDTF1Liberty, GA8.575
September 610:32 AM EDTF0Polk, FL0.330
September 610:02 AM CDTF1Chatham, GA to SC6.0300
September 61:05 PM EDTF0Colleton, SC0.540
September 62:40 PM EDTF1Beaufort, SC1.075
September 62:55 PM EDTF1Jasper, SC2.01001
September 64:40 PM EDTF0Palm Beach, FL0.210
September 67:10 PM EDTF0Saint Johns, FL1.075$10,000
September 67:20 PM EDTF0Saint Johns, FL1.075$20,000
September 610:00 PM EDTF0Pasco, FL0.230

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.