Tornadoes · United States · Florida · 2009

EF0 tornado, Saint Johns County, Florida, April 13, 2009

This EF0 tornado ran 0.2 miles across Saint Johns County on April 13, 2009, touching down at 10:10 PM EDT and reaching 100 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
April 13, 2009
Touchdown
10:10 PM EDT (02:10 UTC)
Lifted
10:11 PM EDT (02:11 UTC)
On the ground
1 minutes
Path length
0.2 miles (0.3 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
County
Saint Johns County
Touchdown point
29.762, -81.252
Lift-off point
29.762, -81.249
Record number
0904132010-01

The warnings

10 minutes of warning. NWS JAX issued a tornado warning for this county at 02:00 UTC, 10 minutes before the tornado touched down, in force until 02:30 UTC.

The county was under a tornado watch, issued at 22:54 UTC and running to 03:42 UTC.

Issued (UTC)ExpiredProductOffice
16:32 UTC22:54 UTCTornado WatchJAX
22:30 UTC23:30 UTCTornado WarningJAX
22:54 UTC03:42 UTCTornado WatchJAX
23:38 UTC00:01 UTCSevere Thunderstorm WarningJAX
02:00 UTC02:30 UTCTornado WarningJAX
02:37 UTC03:01 UTCFlood 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 01:02 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), 00:00Z

2.2 hours before the tornado, 93 km from the path. April 14, 2009.

Skew-T log-pSkew-T log-p diagram, Jacksonville, FL at 00:00Z on 2009-04-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 611 joules per kilogram, CIN -29, lifted condensation level 616 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 2009-04-14The 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 136 square meters per square second, 0 to 6 km bulk shear 55 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
611 J/kg
Mixed-layer CIN
-29 J/kg
Surface CAPE
634 J/kg
Mixed-layer LCL
616 m above ground
0-6 km bulk shear
55 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
136 m²/s²
0-3 km storm-relative helicity
280 m²/s²
Significant tornado parameter
1.0
Supercell composite
7.2
0-3 km lapse rate
5.8 K/km

Open this sounding in Storm Lab

Jacksonville, FL (KJAX), 12:00Z

9.8 hours after it, 93 km from the path. April 14, 2009.

Skew-T log-pSkew-T log-p diagram, Jacksonville, FL at 12:00Z on 2009-04-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 445 joules per kilogram, CIN -154, lifted condensation level 867 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 12:00Z on 2009-04-14The 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 464 square meters per square second, 0 to 6 km bulk shear 68 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
445 J/kg
Mixed-layer CIN
-154 J/kg
Surface CAPE
102 J/kg
Mixed-layer LCL
867 m above ground
0-6 km bulk shear
68 kt
0-1 km bulk shear
44 kt
0-1 km storm-relative helicity
464 m²/s²
0-3 km storm-relative helicity
680 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.5
0-3 km lapse rate
5.1 K/km

Open this sounding in Storm Lab

The surface observations

St Augustine Airpt (SGJ), 24 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:24 UTC71.666.2150° 13 kt231013.9-RA
00:43 UTC71.668180° 13 kt201013.9-RA
00:58 UTC7168170° 15 kt231014.2-RA
01:03 UTC71.668160° 12 kt231014.2-TSRA
01:12 UTC71.668160° 19 kt301013.5TSRA
01:58 UTC69.868280° 5 kt1015.6+TSRA BR
02:23 UTC69.866.2230° 5 kt1015.6VCTS -RA
02:46 UTC6967 3 kt1014.9RA
02:58 UTC6865290° 26 kt371016.3RA
03:08 UTC66.262.6310° 30 kt411016.6-RA
03:17 UTC66.262.6340° 14 kt321016.6-RA
03:21 UTC66.262.6320° 14 kt271016.9-RA
03:26 UTC66.262.6330° 18 kt211016.6
03:58 UTC6562320° 8 kt1015.6

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

The radar

The Jacksonville radar (KJAX), 91 km away, was scanning. The volume nearest the touchdown began at 02:08 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
00:20 UTCTSTM WND DMGGuana River State ParkSt. Johns, FL2 TREES DOWN ON TRAIL AT GUANA RIVER STATE PARK. TIME ESTIMATED BY RADAR.
02:10 UTCTSTM WND DMG2 Nnw Crescent BeachSt. Johns, FLPOSSIBLE TORNADO CAUSED DAMAGE TO HOMES ON GASSETT ROAD. PART OF A ROOF WAS BLOWN OFF A HOUSE. A WOOD FENCE WAS BLOWN INTO A YARD.
03:05 UTCTSTM WND DMGEspanolaFlagler, FLTHE EMERGENCY MANAGER RECEIVED A REPORT OF A POWERLINE DOWN ON MAIN STREET IN ESPANOLA.
03:07 UTCTSTM WND GST 50N Palm CoastFlagler, FLFLAGLER COUNTY EMERGENCY MANAGEMENT REPORTS NUMEROUS 45 TO 50 KNOT WIND GUSTS IN PALM COAST.
03:16 UTCTSTM WND DMGFruit CoveSt. Johns, FLTREE DOWN ON FRUIT COVE DRIVE.

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

This ground now

The live radar over the trackEvery 2009 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

The other tornadoes of April 13, 2009

5 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 138:00 AM CDTEF0Geneva, AL0.350$150,000
April 1312:40 PM EDTEF1Ben Hill, GA2.9100$200,000
April 132:40 PM EDTEF0Appling, GA5.5100
April 134:40 PM EDTEF1McIntosh, GA8.0770$35,000
April 138:45 PM CDTEF0Coffee, TN0.530$12,000

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.