Tornadoes · United States · Florida · 2020

Unrated tornado, Palm Harbor to Denham, Florida, November 30, 2020

From Palm Harbor to Denham, this Unrated tornado ran 12.4 miles across Pinellas and Pasco counties on November 30, 2020, touching down at 6:00 AM EST and reaching 50 yards wide. It killed nobody, and did $1,000 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 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 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. Unratedthis tornado

    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
Unrated
Date
November 30, 2020
Touchdown
6:00 AM EST (11:00 UTC)
Lifted
6:25 AM EST (11:25 UTC)
On the ground
25 minutes
Path length
12.4 miles (20.0 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$1,000
Counties
Pinellas and Pasco counties
Touchdown point
28.100, -82.690
Lift-off point
28.200, -82.520
Record number
2011300500-01

What the Weather Service recorded

Low pressure system moving across the eastern U.S. with attendant cold front extending into the Gulf of Mexico causes thunderstorms producing a tornado and straight-line wind damage.

Developing tornado initially reported via public near Cambridge Blvd. in East Lake in Pinellas County. No damage reported in Pinellas County as path continued northeast intermittently into Pasco County. The tornado was then reported via a storm spotter near SR 54 and Suncoast Parkway where a nearby residence reported downed tree limbs and patio furniture blown around.

Tornado initially reported via public in Pinellas County near Cambridge Blvd. in East Lake before entering Pasco County near Odessa. Tornado then continued for 3 miles and was reported via a storm spotter near SR 54 and Suncoast Parkway, with a nearby residence reporting downed tree limbs and patio furniture blown around.

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

The warnings

4 minutes of warning. NWS TBW issued a tornado warning for this county at 10:56 UTC, 4 minutes before the tornado touched down, in force until 11:30 UTC.

Issued (UTC)ExpiredProductOffice
10:56 UTC11:30 UTCTornado WarningTBW
12:00 UTC00:00 UTCRip Currents StatementTBW
15:00 UTC00:00 UTCHigh Surf AdvisoryTBW

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 Marginal Risk. The outlook in force was issued at 05:50 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), 00:00Z

11.0 hours before the tornado, 53 km from the path. November 30, 2020.

Skew-T log-pSkew-T log-p diagram, Tampa Bay, FL at 00:00Z on 2020-11-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -64045, lifted condensation level 1268 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, Tampa Bay, FL at 00:00Z on 2020-11-30The 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 56 square meters per square second, 0 to 6 km bulk shear 32 knots.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
-64045 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1268 m above ground
0-6 km bulk shear
32 kt
0-1 km bulk shear
16 kt
0-1 km storm-relative helicity
56 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.8 K/km

Open this sounding in Storm Lab

Tampa Bay, FL (KTBW), 12:00Z

1.0 hours after it, 53 km from the path. November 30, 2020.

Skew-T log-pSkew-T log-p diagram, Tampa Bay, FL at 12:00Z on 2020-11-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 328 joules per kilogram, CIN -11, lifted condensation level 739 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, Tampa Bay, FL at 12:00Z on 2020-11-30The 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 309 square meters per square second, 0 to 6 km bulk shear 39 knots.1939587897Sfc1 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
328 J/kg
Mixed-layer CIN
-11 J/kg
Surface CAPE
620 J/kg
Mixed-layer LCL
739 m above ground
0-6 km bulk shear
39 kt
0-1 km bulk shear
33 kt
0-1 km storm-relative helicity
309 m²/s²
0-3 km storm-relative helicity
336 m²/s²
Significant tornado parameter
0.5
Supercell composite
4.8
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

The surface observations

Tampa International Airport (TPA), 22 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
09:53 UTC7570190° 15 kt211010.8
10:53 UTC7570190° 16 kt211010.8
11:00 UTC7570190° 14 kt211010.8VCTS
11:15 UTC7570190° 14 kt1010.5
11:43 UTC7470190° 16 kt211010.8TSRA BR
11:49 UTC73.469.8240° 11 kt261010.8TSRA BR
11:53 UTC73.469.8240° 13 kt261011.2TSRA BR
12:08 UTC7269260° 9 kt1011.2-TSRA BR
12:12 UTC7269270° 14 kt201011.2-TSRA
12:33 UTC7268290° 15 kt241011.5-RA
12:53 UTC7066300° 13 kt221011.9-RA BR

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

The radar

The Tampa radar (KTBW), 53 km away, was scanning. The volume nearest the touchdown began at 11:01 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
11:02 UTCTORNADO4 N OldsmarPinellas, FLPUBLIC REPORTED TORNADO FORMING OVER CAMBRIDGE BLVD. IN PALM HARBOR. TIME ESTIMATED BY RADAR.
11:20 UTCTORNADO4 E OdessaPasco, FLSPOTTER REPORT OF A TORNADO BETWEEN 620-625 AM NEAR STATE ROAD 54 AND SUNCOAST PARKWAY. FAMILY RECEIVED WARNING ON MOBILE PHONE ALERT AND TOOK SHELTER IN BATHROOM. SPOTTER MENTIONED HEARING WIND/TRAIN SOUND AS BRIEF TORN

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

This ground now

The live radar over the trackEvery 2020 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

The other tornadoes of November 30, 2020

4 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
November 303:10 AM ESTEF1Madison, FL5.5475$100,000
November 302:37 PM ESTEF1Cecil, MD3.475
November 303:13 PM ESTEF0Caroline, MD5.375
November 303:52 PM ESTEF0Montgomery, PA0.9100

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.