F1 tornado, Franklin, Massachusetts, August 21, 2004

1. F040 to 72 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. F173 to 112 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. 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.

4. 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.

5. F4207 to 260 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. 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.

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.

Rating

F1

Date

August 21, 2004

Touchdown

3:55 PM EDT (19:55 UTC)

Path length

6.0 miles (9.7 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

Property damage

$1.5 million

County

Norfolk County

Touchdown point

42.080, -71.400

Lift-off point

42.070, -71.330

Record number

468

An early morning severe thunderstorm in Leominster downed large tree limbs.Thunderstorms developed again that afternoon and caused damage in parts of eastern Massachusetts. One storm spawned a weak tornado that took a long and narrow, but very discrete path across western Norfolk County, according to a National Weather Service storm survey. The tornado touched down near Farm Hill Road in West Wrentham near the Rhode Island border. It traveled on the ground for 6 miles to the northeast, passing over southeasternmost Franklin, Interstate 495, Lake Pearl, the northern part of Lake Archer, and ending up near the Wrentham State School, which is near the border with the town of Norfolk. The tornado damage was classified as F1 at two locations: on Summer Street in Franklin and in a subdivision between Lake Pearl and Lake Archer. Wind speeds were estimated at 90 mph in these areas. Tall oak and pine trees were snapped and uprooted at their bases. Many large trees landed on houses throughout Wrentham causing additional damage. The remainder of the tornado's track was considered as F0 with estimated wind speeds of 70 mph. The path width ranged from as narrow as 40 feet to as wide as 120 feet, or 40 yards. One eyewitness near the initial touchdown site saw trees swirling around in mid-air from the front window of her home and heard an unusual roaring sound. No injuries were reported.The same thunderstorm which spawned the tornado weakened as it moved across central and eastern Norfolk County, but downed several trees from Foxborough to Walpole, Sharon and Dedham. It also downed large branches in Watertown, South Boston, and Hingham.In Townsend, three golfers were struck by lightning at a country club.

F1 tornado

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

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

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 Storm Prediction Center had this point in a Slight Risk. The outlook in force was issued at 16:05 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 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.

Pawtucket (Awos) (SFZ), 20 km from the path, in the two hours either side.

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

The Boston radar (KBOX), 23 km away, was scanning. The volume nearest the touchdown began at 19:53 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.

The live radar over the trackEvery 2004 tornado in MassachusettsEvery tornado in Massachusetts since 1950Warnings in force in Massachusetts nowThe forecast where you are

3 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.