Tornadoes · United States · Florida · 2017

EF2 tornado, Saint Johns County, Florida, September 10, 2017

This EF2 tornado ran 1.2 miles across Saint Johns County on September 10, 2017, touching down at 1:15 AM EDT and reaching 300 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 mph

    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 mphthis tornado

    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
EF2
Date
September 10, 2017
Touchdown
1:15 AM EDT (05:15 UTC)
Lifted
1:20 AM EDT (05:20 UTC)
On the ground
5 minutes
Path length
1.2 miles (1.9 km)
Path width
300 yards (274 m)
Deaths
0
Injuries
0
County
Saint Johns County
Touchdown point
29.720, -81.230
Lift-off point
29.720, -81.250
Record number
1709102315-01

The damage survey

16 damage points were recorded along this path by NWS JAX, in the Damage Assessment Toolkit the survey teams carry. The highest wind the damage implies is 62 mph.

  • approximately 2 inches of storm surge at this particular house which is about 60 inches above street level.
  • 53 East Park Ave Saint Augustine 32084. there was approximately 2 inches of storm surge inundated at 53 E. Park Ave., Saint Augustine, FL 32084. this is about 33 inches up from street level.
  • 45 Bayview Drive. Saint Augustine. storm surge 15" below Matthew surge and 7" above ground.
  • 73 Magnolia Ave. water was about 12 inches above ground level at this particular residence. 6 inches above ground level on the side of house.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a tornado watch, issued at 03:50 UTC and running to 12:00 UTC.

Issued (UTC)ExpiredProductOffice
16:02 UTC03:50 UTCTornado WatchJAX
16:05 UTC16:30 UTCMarine WarningJAX
03:50 UTC12:00 UTCTornado WatchJAX
12:16 UTC21:26 UTCTropical Storm WarningJAX
21:26 UTC19:29 UTCSmall Craft AdvisoryJAX

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 01:12 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

5.3 hours before the tornado, 97 km from the path. September 11, 2017.

Skew-T log-pSkew-T log-p diagram, Jacksonville, FL at 00:00Z on 2017-09-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 270 joules per kilogram, CIN 0, lifted condensation level 514 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 2017-09-11The 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 282 square meters per square second, 0 to 6 km bulk shear 39 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
270 J/kg
Mixed-layer CIN
0 J/kg
Surface CAPE
474 J/kg
Mixed-layer LCL
514 m above ground
0-6 km bulk shear
39 kt
0-1 km bulk shear
42 kt
0-1 km storm-relative helicity
282 m²/s²
0-3 km storm-relative helicity
319 m²/s²
Significant tornado parameter
0.4
Supercell composite
2.9
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

The radar

The Jacksonville radar (KJAX), 96 km away, was scanning. The volume nearest the touchdown began at 05:13 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
02:55 UTCTROPICAL STORMBunnellFlagler, FLFIN ASOS REPORTED A GUST OF 51 KNOTS.
03:49 UTCFLASH FLOOD6 W East PalatkaPutnam, FLPUTNAM COUNTY EM REPORTS FLOODING OF A NURSING HOME IN PALATKA WITH EVACUATIONS ORDERED. PATIENTS ARE BEING TRANSPORTED TO A NEARBY HOSPITAL.
04:25 UTCHURRICANEFlagler BeachFlagler, FL75 MPH WIND GUST REPORTED AT FLAGLER BEACH.
04:25 UTCTROPICAL STORMBunnellFlagler, FL72 MPH WIND GUST REPORTED AT THE FLAGLER EOC.
05:30 UTCHURRICANE5 Sw St. AugustineSt. Johns, FLROOF BLOWN OFF A BARN AT THE 2500 BLOCK OF DEERWOOD LANE. REPORT RELAYED THROUGH MEDIA.
06:00 UTCSTORM SURGE 2Palm CoastFlagler, FLSPOTTER REPORTED WATER JUST OVER 2 FEET OVER THE SEA WALL IN PALM COAST. REPORT RELAYED THROUGH EMA.
07:13 UTCFLASH FLOOD3 Ne BunnellFlagler, FLWAIST DEEP WATER ON EMERSON DRIVE FROM RAINFALL IN PALM COAST.
07:20 UTCHURRICANEFlagler BeachFlagler, FLEMERGENCY MANAGER REPORTED 83 MPH AT FLAGLER BEACH.
07:23 UTCHEAVY RAIN 9.57Palm CoastFlagler, FLEMERGENCY MANAGER REPORTS 9.57 INCHES OF STORM TOTAL RAINFALL. 4.07 INCHES OF RAIN PAST 24 HOURS.
07:30 UTCTROPICAL STORM4 Se Fruit CoveSt. Johns, FLPUBLIC REPORTED MULTIPLE TREES DOWN AT THE TRINITY RESCUE MISSION FREEDOM FARM FACILITY. ALSO A ROOF WAS BLOWN OFF ONE OF THE BUILDINGS AS WELL AS A FENCE DOWN ON THE PROPERTY. TIME IS ESTIMATED.
07:47 UTCFLOOD1 N Daytona BeachVolusia, FLDAYTONA BEACH POLICE REPORT SIGNIFICANT FLOODING EAST OF US 1
08:00 UTCSTORM SURGE 04 Sse MarinelandFlagler, FLREPORTS OF STORM SURGE IN MARINELAND ACRES JUST SOUTH OF WASHINGTON OAKS STATE PARK. PUBLIC REPORTS OF SURGE SIMILAR TO HURRICANE MATTHEW.

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

This ground now

The live radar over the trackEvery 2017 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

The other tornadoes of September 10, 2017

15 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
September 108:59 AM EDTEF1Hardee, FL0.050$40,000
September 109:19 AM EDTEF0Brevard, FL0.250
September 1011:00 AM EDTEF1Brevard, FL1.375
September 1011:19 AM EDTEF2Polk, FL0.650$20,000
September 1011:24 AM EDTEF1Brevard, FL1.275
September 101:40 PM EDTEF1Saint Johns, FL1.250
September 105:48 PM EDTEF2Brevard, FL1.6125
September 106:00 PM EDTEF1Brevard, FL0.560
September 106:28 PM EDTEF1Lake, FL3.8500
September 107:50 PM EDTEF1Saint Johns, FL5.0200
September 108:13 PM EDTEF0Flagler, FL4.1200
September 109:04 PM EDTEF1Volusia, FL0.8175
September 109:04 PM EDTEF1Brevard, FL1.250
September 109:14 PM EDTEF1Brevard, FL0.360
September 109:48 PM EDTEF1Brevard, FL3.460

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.