Major Severe Thunderstorm Outbreak
Friday, May 29, 1998

A classic spring outbreak of severe thunderstorms developed ahead of a strong cold front moving into the northeast during the afternoon of Friday, May 29.

Several necessary parameters for severe thunderstorms came together over the northeast to support this event. Very warm and humid air flowed into New York and New England ahead of a cold front. Air temperatures, due to strong heating, rose to a high of 87 at Albany, with dewpoint temperatures surging into the low and mid 60's. Those temperature and moisture values are quite high for May. A big key ingredient in creating and supporting this severe weather event was the northwest flow aloft at the jet stream level which allowed the air aloft to cool creating instability which allows air near ground to easily rise given a front in the vicinity to lift it. The wind shear environment of the atmosphere, which is something meteorologists must look at in determining whether severe weather will occur and if so what type, was what we call unidirectional. In other words, the wind direction from the ground up in the atmosphere did not change very much, but the speed increased significantly. Unidirectional wind shear favors the development of squall lines as was the case in this event.

A squall line formed well ahead of the cold front during the morning in western New York and quickly moved east through the course of the day. The Storm Prediction Center in Norman Oklahoma issued a severe thunderstorm watch for eastern New York and a second watch box for western New England for this event in advance of the squall line.

Squall lines are notorious for producing wind damage over a wide region and in some cases large hail. This squall line was fairly vigorous and did produce widespread wind damage through New York and especially western New England before weakening as it moved across central and eastern New England during the evening and early nighttime hours. One very interesting aspect to this particular squall line was in its life cycle. Typically, individual as well as lines of thunderstorms produce an outflow boundary of rain cooled air that runs ahead of the thunderstorms. Often, this outflow boundary, or mini cold front, will cut off the supply of warm moist air, which feeds the line. The line then quickly weakens and falls apart. A very good example of this phase of the lifecycle of a squall line occurred in this event immediately over the Capital District. The very powerful outflow boundary of this squall line moved into the Capital District during the late afternoon with about a fifteen minute period of up to 50mph wind gusts, with no rain, and no lightning or thunder. Just east of the Hudson river however, a new line of thunderstorms formed on the outflow boundary which went on to produce frequent lightning and damaging wind in extreme eastern New York and western New England. So, the squall line appeared to jump over the Capital District when in reality the original line had rapidly weakened and a new line formed in an area where the atmosphere was still ripe with hot and humid air. The following is a listing of the severe weather reports received by channel 6 and the National Weather Service in Albany for this event.




Storm Report

Fairfield Herkimer NY Wind damage, many trees down, 2:33pm
Stratford Fulton NY Wind damage and power outages county wide, 2:30 to 3:00 pm
Dolgeville Herkimer NY Wind damage, trees/power lines down
St. Johnsville Montgomery NY Wind damage, 2:57 pm
Piseco Hamilton NY Wind damage, trees down, power out
Indian Lake Hamilton NY Wind damage, Tree tops blown off, 3:08 pm
Warrensburg Warren NY Wind damage, Tree down, 3:25 pm
Central Bridge Schoharie NY Wind damage, Trees down 3:27 pm
Delanson Schenectady NY Wind damage, numerous trees down 3:30 pm
Malta Saratoga NY Wind damage, Trees/power lines down 3:34 pm
Greenfield Center Saratoga NY Wind damage, Trees/power lines down 3:34 pm
Rock City Falls Saratoga NY Wind damage, Trees down 3:39 pm
Amsterdam Montgomery NY Wind damage county wide, Trees and wires down 3:45 pm
Granville Washington NY Wind damage, Trees/wire down 3:48 pm
Fort Edward Washington NY Wind damage, 3:48 pm
Berne Albany NY Wind damage, 3:48 pm
Whitehall Washington NY Wind damage, Trees down, 3:48 pm
Glenville Schenectady NY Wind damage, Trees down, 3:55 pm
Hoosick Falls Rensselaer NY Wind damage throughout the northern part of the county, 4:20 pm
Leeds Greene NY Wind damage, Trees down, 4:35 pm
Catskill Greene NY Wind damage, Trees down, 4:35 pm
Kinderhook Columbia NY Wind damage, Trees down, 4:41 pm
East Greenbush Rensselaer NY Wind damage, Large tree branches down, 4:45 pm
Cheshire Berkshire MA Wind damage, Trees down, 4:53 pm
Bennington Bennington VT Wind damage, Trees/wires down, 4:55 pm
Woodstock Ulster NY Wind damage, Trees down, 5:03 pm
Kingston Ulster NY Wind damage, Trees down, 5:18 pm
Great Barrington Berkshire NY Wind damage, Trees down, 5:30 pm
Poughkeepsie Ulster NY Wind damage, Trees down, 5:45 pm