F1 tornado, Ontario, New York, May 11, 2003

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

May 11, 2003

Touchdown

3:30 PM EDT (19:30 UTC)

Path length

2.3 miles (3.7 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$150,000

County

Wayne County

Touchdown point

43.220, -77.280

Lift-off point

43.220, -77.280

Record number

272

Strong thunderstorms moved across the Genesee Valley, Western Finger Lakes and eastern Lake Ontario region during the afternoon hours. The thunderstorm winds, estimated to 65 mph, downed trees in Stafford, Spencerport, and Oswego. Power lines were downed in Adams. In Spencerport, a NWS survey determined damage to trees and several structures was consistent with straight line winds. In Ontario, Wayne county, the survey team determined the damage was caused by a weak tornado. The tornado touched down around 3:30 PM EDT. The initial touchdown occurred near the intersection of Willits and Lakeside Roads. Two homes, an automobile and a storage shed suffered damage. The tornado then touched down on Slocum Road where three more homes sustained damage and several large trees were felled. The final touchdown occured on Lake Road where the roof of a shed was torn off, trees were downed and a power pole and transformer were sheared off. The tornado winds were estimated between 75 and 100 mph. The path length was 2.25 miles, but the tornado was not on the ground the entire path length. The path width was 50 yards.

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 Moderate Risk, with a 0.15 chance of a tornado within 25 miles. The outlook in force was issued at 12:21 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.

Rochester/Monroe Co (ROC), 34 km from the path, in the two hours either side.

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

The Buffalo radar (KBUF), 122 km away, was scanning. The volume nearest the touchdown began at 19:30 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 2003 tornado in New YorkEvery tornado in New York since 1950Warnings in force in New York nowThe forecast where you are

13 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.