F1 tornado, Mt Airy, North Carolina, September 29, 1999

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

September 29, 1999

Touchdown

6:20 PM EDT (22:20 UTC)

Path length

2.0 miles (3.2 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

Property damage

$150,000

County

Surry County

Touchdown point

36.530, -80.570

Lift-off point

36.550, -80.550

Record number

647

Thunderstorms during the early evening of the 29th produced damaging winds, damaging lightning, and spawned a tornado.Thunderstorm winds downed several trees 3.5 miles northeast of Mt Airy.Lightning struck a house, starting a fire that caused major damage.A thunderstorm spawned a tornado 3.5 miles northeast of Mt Airy in Surry County at 1720 EST. The tornado was periodically on the ground for about 2 miles, before dissipating 5.5 miles northeast of Mt Airy. The average width of the tornado was 40 yards wide, with a maximum width of 70 yards wide. The tornado destroyed a mobile home, a large carport and associated garage, damaged or destroyed several out buildings, tore a portion of a roof off of a house, caused minor damage to several other homes, killed several chickens, uprooted numerous trees, knocked down power poles and power lines, and broke off large tree limbs. Some of the debris from the tornado was carried up to 2 miles downstream. Wooden attic stairs, that likely weighed in excess of 80 pounds, were carried about a quarter of a mile downstream. Maximum winds were estimated to be from 100 to 110 miles an hour.

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. One was issued for the county at another hour that day.

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 General Thunderstorms Risk. The outlook in force was issued at 19:58 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.

Mount_airy/Surry_county_aprt (MWK), 9 km from the path, in the two hours either side.

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

The Roanoke radar (KFCX), 60 km away, was scanning. The volume nearest the touchdown began at 22:22 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 1999 tornado in North CarolinaEvery tornado in North Carolina since 1950Warnings in force in North Carolina nowThe forecast where you are

6 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.