Tornadoes · United States · Florida · 1997
F1 tornado, Mulberry, Florida, October 31, 1997
This F1 tornado ran 4.0 miles across Polk County on October 31, 1997, touching down at 2:15 PM EST and reaching 23 yards wide. It killed nobody, and did $400,000 of property damage.
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.
F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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
- October 31, 1997
- Touchdown
- 2:15 PM EST (19:15 UTC)
- Path length
- 4.0 miles (6.4 km)
- Path width
- 23 yards (21 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $400,000
- County
- Polk County
- Touchdown point
- 27.900, -82.030
- Lift-off point
- 27.930, -81.950
- Record number
- 604
What the Weather Service recorded
A tornado touched down and damaged a warehouse distribution center, overturned two tractor trailers, tore down 100 feet of chain link fence and blew down several power poles along State Road 60 near County Road 676.The tornado touched down a second time and damaged several roofs of homes and downed trees and power poles at the Christina Grove subdivision near State Road 37 and County Road 540A before it lifted and dissipated.
A tornado touched down along State Road 37 near State Road 640 and uprooted or snapped, half-way up, 50 to 60 pine trees, destroyed a shed and caused structural damage to a home in rural western Polk county before it lifted and dissipated.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
6 minutes of warning. NWS TBW issued a tornado warning for this county at 19:09 UTC, 6 minutes before the tornado touched down, in force until 19:55 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 19:09 UTC | 19:55 UTC | Tornado Warning | TBW |
| 19:50 UTC | 20:35 UTC | Tornado Warning | TBW |
| 20:44 UTC | 21:15 UTC | Severe Thunderstorm Warning | TBW |
| 22:31 UTC | 23:20 UTC | Severe Thunderstorm Warning | TBW |
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. The outlook in force was issued at 18:27 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.
Tampa Bay, FL (KTBW), 12:00Z
7.3 hours before the tornado, 47 km from the path. October 31, 1997.
- Mixed-layer CAPE
- 1009 J/kg
- Mixed-layer CIN
- -17 J/kg
- Surface CAPE
- 37 J/kg
- Mixed-layer LCL
- 577 m above ground
- 0-6 km bulk shear
- 17 kt
- 0-1 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 146 m²/s²
- 0-3 km storm-relative helicity
- 197 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.0
- 0-3 km lapse rate
- 4.9 K/km
Tampa Bay, FL (KTBW), 00:00Z
4.7 hours after it, 47 km from the path. November 1, 1997.
- Mixed-layer CAPE
- 2425 J/kg
- Mixed-layer CIN
- -2 J/kg
- Surface CAPE
- 2135 J/kg
- Mixed-layer LCL
- 555 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 166 m²/s²
- 0-3 km storm-relative helicity
- 168 m²/s²
- Significant tornado parameter
- 2.1
- Supercell composite
- 12.7
- 0-3 km lapse rate
- 6.1 K/km
This ground now
The live radar over the trackEvery 1997 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are
The other tornadoes of October 31, 1997
6 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| October 31 | 12:00 PM EST | F0 | Sarasota, FL | 0.1 | 10 | |||
| October 31 | 12:25 PM EST | F0 | Manatee, FL | 0.1 | 10 | $10,000 | ||
| October 31 | 12:58 PM EST | F0 | Manatee, FL | 0.1 | 10 | $10,000 | ||
| October 31 | 1:17 PM EST | F0 | Manatee, FL | 0.3 | 10 | $60,000 | ||
| October 31 | 2:30 PM EST | F1 | Polk, FL | 0.5 | 30 | $50,000 | ||
| October 31 | 5:12 PM EST | F0 | Hillsborough, FL | 1.0 | 10 | $10,000 |
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.