EF1 tornado, South Amsterdam to Glenville, New York, September 4, 2011

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 mphthis tornado

   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. 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

EF1

Date

September 4, 2011

Touchdown

5:20 PM EDT (21:20 UTC)

Lifted

5:35 PM EDT (21:35 UTC)

On the ground

15 minutes

Path length

7.0 miles (11.2 km)

Path width

880 yards (805 m)

Deaths

0

Injuries

0

Counties

Schenectady and Montgomery counties

Touchdown point

42.898, -74.168

Lift-off point

42.948, -74.048

Record number

1109041520-01

A warm, moist and unstable airmass was in place across the region with a slow moving cold front approaching from the Great Lakes Region. A pre-frontal trough developed ahead of the approaching cold front Sunday afternoon, September 4th, and this, in combination with the approach of an upper level trough, triggered convection across east central New York during the mid afternoon into the early evening. The storms produced very heavy rainfall which resulted in some flash flooding. The severe thunderstorms produced damaging winds. A supercell developed over Montgomery County, where a tornado touched down before tracking northeastward into Schenectady County.

A tornado touched down in the Town of Florida in Montgomery County. It moved northeast to the western end of Glenville in Schenectady County. Damage was extensive along the entire path length, with the worst damage in the Town of Cranesville in Montgomery County. Damage included numerous trees snapped off and uprooted, broken windows to homes, shingles stripped off roof tops, and some houses which had parts of their roofs torn off. Numerous sheds and out buildings were destroyed. The tornado was caught on video from the Mohawk Travel Plaza rest area on the New York State Thruway.

A tornado touched down in the Town of Florida in Montgomery County. It moved northeast to the western end of Glenville in Schenectady County. Damage was extensive along the entire path length, with the worst damage in the Town of Cranesville in Montgomery County. Damage included numerous trees snapped off and uprooted, broken windows to homes, shingles stripped off roof tops, and some houses which had parts of their roofs torn off. Numerous sheds and out buildings were destroyed.

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.

The county was under a severe thunderstorm watch, issued at 18:45 UTC and running to 01:33 UTC.

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, with a 0.02 chance of a tornado within 25 miles. 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.

The Albany radar (KENX), 38 km away, was scanning. The volume nearest the touchdown began at 21:19 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.

Local storm reports within 60 km of the path, in the three hours either side.

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

The live radar over the trackEvery 2011 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.