Severe T-Storm & Tornado Outbreak
Thursday, July 3, 1997

A major outbreak of severe thunderstorms and tornadoes occurred during the morning and afternoon of July 3. A very strong weather system, by July standards, produced widespread severe weather, including large damaging tornadoes, over the upper plains states on July 1. On July 2, the storm moved east producing a major tornado outbreak over southeastern Michigan, including the metro Detroit area. Finally, on July 3, the storm spun out over the northeast producing the local damaging thunderstorms and isolated tornadoes.

A strong westerly jet stream flow in the upper levels of the atmosphere transported a pocket of very cold air aloft over the northeast. At the surface, a strong low pressure system tracked through southeastern Canada creating a strong south to southeast flow of warm, tropical air into the northeast. Temperatures climbed into the lower and middle 80's with dew point temperatures rising into the lower to middle 70's. The occurrence of very warm and humid air at the ground and very cold air aloft created the necessary instability in the atmosphere to support thunderstorm updrafts along the cold front which extended into New York from the low center. The southeast surface wind ahead of the front was enhanced by the development of two lines of convection early in the day which increased the amount of directional and speed wind shear in the atmosphere, an important parameter for tornado development that is not normally present in northeast severe weather events.

The Storm Prediction Center in Norman, Oklahoma issued a tornado watch during the morning for much of New York as thunderstorms developed very quickly. Severe thunderstorm warnings for Herkimer, Saratoga, Warren, and Washington counties were issued for a line of storms which moved in during the early afternoon. These storms produced scattered wind damage and large hail. A second, and more intense clustering of scattered thunderstorms moved into the Capital Region during the mid to late afternoon. These storms, as they intercepted the tropical, highly sheared wind flow in the Hudson valley, rapidly intensified and a few began to rotate. These rotating thunderstorms are called supercell thunderstorms and they sometimes produce tornadoes. One of the supercell storms, located in southern Columbia county, became tornadic at 5:15pm as indicated by the Albany Doppler weather radar. The following is a time line of the tornado reports as received by the Albany National Weather Service.

- 5:15pm: A tornado warning was issued by the Albany National Weather Service office for Columbia and Berkshire counties.

- 5:30pm: A tornado moved into the Center Hill area of Copake, Columbia county producing F-1 damage to trees and buildings. (F-1 tornado winds = 74-112mph)

- 5:45pm: Storm spotters report a tornado on the ground in Berkshire county, MA at route 23 moving to the east, northeast. A tornado warning for Berkshire county remains in effect.

- 6:14pm: The supercell storm undergoes a normal metamorphosis where the storm's center of circulation occludes and a new circulation center forms. At this stage of the storm's life cycle, the first tornado separates from the supercell and continues for awhile before dissipating and a second tornado forms from the parent storm. So, at this time, Doppler radar indicated two tornadoes, the original one near Monterey, MA and a developing one near the Great Barrington fairgrounds. A second tornado warning is issued for Berkshire county at this time.

- 6:25pm: A tornado moves through a small part of Becket, MA, in Berkshire county.

- 6:30pm: A tornado moves along the Pittsfield, Lenox line.

- 6:40pm: Storm spotters report a tornado in Otis, MA with debris falling from the sky.

- 7:16pm: Doppler radar indicated that another tornado was forming from a new supercell thunderstorm near Lebanon Springs in Columbia county. A tornado warning is issued for northeastern Columbia county and for the third time, Berkshire county.

- 7:28pm: Storm spotters report a rotating wall cloud between Canaan in northeastern Columbia county and Richmond in Berkshire county, MA.

- 8:17pm: A fourth tornado warning is issued for Berkshire county at this time. Doppler radar indicated a tornado near Hinsdale moving east at 30mph.

The following is a tabular listing of all the severe weather reports received from this event by the Albany National Weather Service office and here at NewsCenter 6.

Town

County

State

Storm Report

Time

Hartwick Otsego NY Wind damage, trees down 1:50pm
Cooperstown Otsego NY Wind damage, trees blocking route 28 2:00pm
Middleburg Schoharie NY 3/4" Hail covering the ground 2:30pm
Charlotteville Schoharie NY Trailor blown off foundation 2:35pm
Middleburg Schoharie NY Wind damage, wires down 2:52pm
Berne Albany NY 3/4" hail 3:10pm
Selkirk Albany NY Planes flipped and sheds damaged 4:00pm
Copake Columbia NY F-1 Tornado 5:30pm
Egremont Plain Berkshire MA Tornado 5:45pm
Hillsdale Columbia NY 1.75" diameter hail, tree limbs down 5:46pm
Monterey Berkshire MA F-1/F-2 Tornado 6:15pm
Becket Berkshire NY Tornado 6:25pm
Pittsfield/Lenox Berkshire MA Tornado 6:30pm
Otis Berkshire MA F-2 tornado (Winds 113-157mph) 6:40pm
Canaan Columbia NY Torndao, structure destroyed 7:18pm
Richmond Berkshire MA Rotating wall cloud 7:25pm