Tornadoes · United States · Florida · 2009

EF0 tornado, Casselberry, Florida, May 19, 2009

This EF0 tornado ran 0.1 miles across Seminole County on May 19, 2009, touching down at 11:42 PM EDT and reaching 50 yards wide. It killed nobody, and did $100,000 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
May 19, 2009
Touchdown
11:42 PM EDT (03:42 UTC)
Lifted
11:43 PM EDT (03:43 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.1 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$100,000
County
Seminole County
Touchdown point
28.672, -81.308
Lift-off point
28.672, -81.308
Record number
0905192142-01

What the Weather Service recorded

A nearly stationary upper-level low over the Gulf of Mexico combined with a weak surface low near south Florida produced favorable shear conditions for shallow rotation within several onshore-moving showers and thunderstorms. One of these cells produced a brief EF0 tornado touchdown, removing large portion of roofs from several homes in Casselberry and carrying debris downstream. An isolated severe thunderstorm also produced minor wind damage in Orange County.

A EF0 tornado touched down briefly and removed the roofs from a single family home and mobile home. Portions of the roofs and other debris were carried downstream, with large metal pieces deposited in trees. Another 8 homes sustained minor damage.

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

The warnings

7 minutes of warning. NWS MLB issued a tornado warning for this county at 03:35 UTC, 7 minutes before the tornado touched down, in force until 04:00 UTC.

Issued (UTC)ExpiredProductOffice
13:05 UTC00:00 UTCFlood WatchMLB
03:35 UTC04:00 UTCTornado WarningMLB
04:05 UTC04:30 UTCTornado WarningMLB
05:11 UTC07:15 UTCFlood AdvisoryMLB
05:26 UTC06:00 UTCTornado WarningMLB
07:17 UTC09:15 UTCFlood AdvisoryMLB
15:00 UTC00:00 UTCLake Wind AdvisoryMLB

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 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.

Cape Canaveral, FL (KXMR), 00:00Z

3.7 hours before the tornado, 82 km from the path. May 20, 2009.

Skew-T log-pSkew-T log-p diagram, Cape Canaveral, FL at 00:00Z on 2009-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 597 joules per kilogram, CIN 0, lifted condensation level 509 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 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, Cape Canaveral, FL at 00:00Z on 2009-05-20The 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 47 square meters per square second, 0 to 6 km bulk shear 20 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
597 J/kg
Mixed-layer CIN
0 J/kg
Surface CAPE
1410 J/kg
Mixed-layer LCL
509 m above ground
0-6 km bulk shear
20 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
47 m²/s²
0-3 km storm-relative helicity
64 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6
0-3 km lapse rate
5.8 K/km

Open this sounding in Storm Lab

The radar

The Melbourne radar (KMLB), 89 km away, was scanning. The volume nearest the touchdown began at 03:39 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
03:42 UTCTSTM WND DMGCasselberrySeminole, FLPOSSIBLE ROOF DAMAGE ON LAKE SHORE DRIVE IN CASSELBERRY...FIRE CREWS RESPONDING
03:42 UTCTORNADOCasselberrySeminole, FLLOW END EF0 TORNADO -65 MPH- WIDTH 50 YARDS PATH LENGTH 1.5 MILES AT LAKE SHORE AND LAKE AVE
03:50 UTCTSTM WND DMGApopkaOrange, FLTREE ON A HOUSE ON CLARCONA ROAD IN APOPKA
04:46 UTCTSTM WND GST 54SanfordSeminole, FLKSFB AIRPORT MEASURED 54 MPH.

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 May 19, 2009

1 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 193:22 PM MDTEF0Mesa, CO0.350

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.