Major Severe Weather Outbreak & Regional Moderate High Wind Event
Friday December 1, 2006  

December 1, 2006 Lightning Display over Albany, NY

Photographer: Mark Ellinwood
An intense lightning display over Albany, NY during the early evening of December 1, 2006, associated with the passage of a severe thunderstorm squall line. The photograph was taken from the tenth floor of the Eastman Tower on State Quad. at SUNY Albany. The Empire State Plaza is visible in the center bottom of the photograph.


Between 4pm and 7:30pm on Friday, December 1 the atmosphere unleashed an unusual outbreak of severe thunderstorms, more typical of the spring or summer, rather than December. Short line segments of damaging thunderstorms consolidated into a solid squall line over the Capital Region bringing a brief torrent of horizontally blown rain, frequent blinding lightning, and blasts of wind up to 85 mph to many locations. The severe weather event stretched from western Pennsylvania from the morning to central New York and central Pennsylvania during the early to mid afternoon, then across the entire CBS6 coverage area from Delaware, Otsego, and Herkimer counties to the west, through Rutland, Bennington, Berkshire, and Litchfield counties to the east during the late afternoon and the evening. Severe thunderstorm warnings were issued for every county in eastern New York and western New England, except Warren and Washington. And tornado warnings were issued for eastern Ulster, northern Dutchess, and northern Litchfield counties during the early evening. No tornado touchdowns were confirmed by the Albany National Weather Service after storm survey teams investigated pockets of particularly heavy damage at Lenox in Berkshire County, MA and in and around Rhinebeck in Dutchess County. However, a tornado rated F2 on the Fujita tornado intensity scale was confirmed in Luzerne County, PA, not to far over the New York border, affecting Hollenback Township, Dorrance, and Wright Township along a fifteen mile continuous path. (Winds in F2 tornadoes range from 113-157 mph.) And two additional tornadoes, rated F0 (40-72 mph) and F1 (73 to 112 mph) were confirmed in Pike County, PA affecting manly rural areas resulting in extensive tree damage. The damage that the thunderstorms produced locally, however, came from violent straight line winds that were estimated by an Albany NWS damage survey team to range from 80-85 mph in Lenox, MA and from 75-80 mph in the Rhinebeck/Sepasco Lake area of northern Dutchess County. The severe weather lasted only a matter of five to ten minutes at any one location, but it was a very high impact five to ten minutes that left many areas with tree and utility line damage and thousands without power. At Tanglewood alone in Lenox, MA, according to the Berkshire Eagle, an estimated 300 trees were blown down with damage being done to the roofs of the mansion and carriage house. The damage estimate at just Tanglewood was $250,000.00.

The Set Up:
A unique combination of particularly strong weather players in the atmosphere and an unusually strong contrast in temperature and dewpoint over a very short distance centered over the local area, set the stage for the powerful outbreak of late day and out of season severe thunderstorms, and subsequent period of strong gradient winds that persisted into Saturday morning, December 2.

The Players:
1) Strong Temperature Contrast Zone
Initially very mild and moist air, by December standards, flowed into the Northeast in the day prior to the severe outbreak with temperatures on November 30 climbing into the middle 60s and dewpoint temperatures jumping into the middle 50s. Temperatures remained in the 60s and dewpoints in the 50s, under the influence of a moderately strong southerly flow, well into the early morning hours of Friday December 1. A backdoor cold front, however, dropped into the region from the north during the pre-dawn and early morning hours on the 1st causing a sharp drop in temperatures into the upper 30s and the lower 40s from the Mohawk valley, Capital Region, and the lower elevations of Bennington County on north.

In fact, WeatherNet 6 spotters indicated that the very shallow layer of cold air briefly made it as far south as Catskill and into the northern portions of Chatham in Columbia county, before retreating back to the north. At one point in the afternoon, according to WeatherNet 6 spotter Jim Meehan, the temperature within the town of Chatham ranged from the low 40s on the north side of town, to the mid 60s on the south side of town.

The temperature contrast on either side of the semi-stationary front ranged from a huge 25° to 30° over as little as a few miles. Sharp gradients in temperature over short distances are favorable regions for strong low pressure systems to develop, as was the case in this event.

Wind, Temperature, and Dewpoint Track @ Albany, NY on December 1, 2006

Time
Wind (mph)
Temperature
Dewpoint
Midnight South 18 G 23 64° 54°
1:00 am South 14 G 20 63° 54°
2:00 am South 12 63° 54°
3:00 am South 7 63° 55°
4:00 am North 3 60° 55°
5:00 am Calm 58° 56°
6:00 am Calm 57° 55°
7:00 am NE 8 52° 50°
8:00 am North 13 48° 45°
9:00 am NE 14 46° 43°
10:00 am North 7 43° 41°
11:00 am North 10 43° 40°
Noon North 10 43° 40°
1:00 pm North 9 42° 40°
2:00 pm North 8 42° 40°
3:00 pm NE 5 41° 40°
4:00 pm NW 3 41° 39°
5:00 pm Calm 42° 40°
6:00 pm South 18 G 46 55° 53°
7:00 pm NW 8 60° 55°
8:00 pm NW 33 G 41 56° 50°
9:00 pm NW 20 G 30 48° 39°
10:00 pm NW 10 G 24 46° 38°
11:00 pm NW 6 46° 38°
Midnight North 5 46° 38°

2) Jet Stream Features
At the jet stream level, an intense speed maximum of 160 mph raced just to the southeast of the region during the afternoon and evening of the 1st putting the entire Northeast in a highly favorable region of strong atmospheric lift. Under the powerful upper air jet, strong winds ranging from 50 and 70 mph extended down very low in the atmosphere to about the 1000' level . In addition, a powerful upper level low pressure system imbedded within the jet stream flow swung through at exactly the same time that the 160 mph jet was in the perfect spot for enhancing lift over the local region. The net result of these two major upper level features working in perfect unison caused layers of air to rapidly ascend which in turn caused surface air pressures to rapidly drop with the formation of a surface storm. The dropping air pressures subsequently caused the winds in the atmosphere from the surface up through the mid levels to increase further during the afternoon and the evening providing a tremendous amount of kinetic energy to the atmosphere, that thunderstorms could interact with creating a strong high wind potential in the individual thunderstorm's downdraft regions.

3) Rapidly Developing and Intensifying Surface Storm
The result of the strong contrast in temperature and dewpoint over the region and the tight horizontal gradient that resulted, and the passage of the powerful jet and upper air low pressure system that generated strong winds through a very deep layer of the atmosphere, came together to produce a surface storm on the temperature contrast boundary over New York. The surface storm caused the winds in the warm sector of air which extended just south of the Mohawk valley and Capital Region, to gust up to 35 mph from the southeast, while the winds aloft were much stronger out of the southwest and west. The resultant shear profiles (change in wind direction and speed with height) along and south of the front became extraordinarily favorable, providing enough instability existed, for not only widespread damaging straight line winds, but for tornadoes as well in any thunderstorms that formed.

The Event
As the surface storm rapidly intensified during the middle to late afternoon, so too did the lines of thunderstorms that were associated with it and it's attendant cold front that was swinging in from the west. What had amounted to short line segments of thunderstorms over central New York, consolidated over the Capital Region into a solid and formidable squall line. Lightning strikes between 5:00 and 5:30pm tripled indicating a rapidly intensifying system. Despite the entire northern half of the local area remaining in the shallow cold air on the north side of the front during the event, damaging winds were still able to mix down to the ground right through the temperature inversion (warm air over cold air) as the line went through. (Typically shallow layers of cold air prevent vertical mixing of layers of air and thus a significant reduction in the amount of wind that can come down from higher levels. In this case, however, the downdrafts in some areas were so strong that they punched through the inversion creating damaging gusts at ground level.) A side effect of the squall line's passage through the colder areas was a rapid mixing out of the shallow cold air, with average temperature spikes of fifteen degrees in a matter of minutes which lead to the areas of fog and drizzle hat had been in place to quickly dissipate with building and car windows reportedly rapidly fogging up.

The most widespread wind damage with the squall line occurred along and south of the front in the warmer and more humid air, where the atmosphere was more readily able to mix down damaging gusts of wind through the severe thunderstorm downdrafts that interacted with the high momentum air that existed not to far above the surface. The line rapidly intensified in Berkshire County, MA by about 6:30pm, where widespread wind damage occurred, attributed to 80 to 85 mph straight line winds. Further south, in eastern Ulster, northern Dutchess, and Litchfield counties, the near 70° degree air and low 60° degree dewpoints created enough instability for the existing wind shear to be optimized allowing several rotating thunderstorms to spin up where tornadoes could have formed.

Tornado Warnings:
At 6:01pm Tornado Warning issued for Ulster County until 6:45pm
At 6:26pm Tornado Warning issued for northwest Dutchess County until 7:30pm
At 7:03pm Tornado Warning issued for Litchfield County, CT until 7:45pm

Surveys by Albany National Weather Service damage teams in the subsequent days after the event did not yield any evidence of tornado touchdowns. However, straight line winds up to 80 mph were estimated to have caused the damage that was observed, especially in the Rhinebeck area of Dutchess County.

By 7:30pm the line, which had arrived in the western Catskills a little bit after 4pm, had cleared Berkshire and Litchfield counties bringing a quick end to the severe weather. A lull in the weather and the wind persisted for one to two hours after the passage of the squall line and the strong storm that was driving it. As the storm pulled away, and continued to strengthen northeast of the region, strong gradient winds developed between 8pm and 9pm which persisted into Saturday morning. Regional wind gusts, as cooler air returned to the region ranged from 30-45 mph on average with a few higher elevation gusts to 50 mph.

Click Here to view a series of Doppler radar base reflectivity images of the December 1, 2006 Severe Thunderstorm Event

Table #1 lists the observed peak wind gusts associated with the passage of the severe thunderstorm squall line and subsequent regional moderate high wind event that followed from December 1 through December 2, 2006

Table #1

Town
County
Peak Reported Wind Gust
Estimated Time of Wind Gust
Albany (Airport) Albany 46 mph 5:46pm 12/1
Albany (NWS) Albany 44 mph 7:41am 12/2
North Adams, MA Berkshire 58 mph 6:34pm 12/1
Pittsfield, MA Berkshire 46 mph 6:55pm 12/1
Livingston Columbia 40 mph 4:56pm 12/1
Kinderhook Columbia 36 mph 6:30pm 12/1
Poughkeepsie Dutchess 44 mph 8:57pm, 12/1
Catskill Greene 41 mph 6:26pm 12/1
Indian Lake Hamilton 44 mph 7:23pm 12/1
Fairfield Herkimer 49 mph 7:00pm 12/1
Glen Mongtomery 46 mph 5:14pm 12/1
Stephentown Rensselaer 49 mph 6:27pm 12/1
Glens Falls Warren 37 mph 12:56am 12/2
Bennington, VT Bennington 58 mph 6:00pm 12/1
Pawlet, VT Rutland 59 mph 6:17pm 12/1

Table #2 lists the storm reports collected by the local National Weather Service offices for eastern New York and western New England which are used to verify the warnings that were issued. These reports are just a sample of the damage that occurred throughout the region from both the thunderstorm and gradient winds. Additional reports received by CBS6 are included in this tabulation as well.

p class="newscopy">Click Here to view a series of storm damage photographs from the Rhinebeck area of Dutchess County, NY

Table #2

Town
County
Damage Report
Estimated Time Damage Occurred
Ellenville Ulster Non-T'storm wind damage, tree blown onto a home causing one fatality 4:24pm
Hensonville Greene Non-T'storm wind damage, trees down 4:30pm
Ohio Herkimer Trees blown down by passage of severe T'storm 4:51pm
Big Moose Herkimer Trees down due to severe T'storm 4:52pm
Summit Schoharie Trees down due to severe T'storm 5:00pm
Johnstown Fulton Numerous trees blown down 5:05pm
Glen Montgomery Trees blown down by severe T'storm 5:09pm
Speculator Hamilton Many trees downed by severe T'storm, trees reported to have fallen on a trailer with minor injuries 5:13pm
Blue Mountain Lake Hamilton WxNet report of high winds and power being knocked out 5:15pm
Halcottsville Delaware 0.88" diameter hail 5:24pm
Duanesburg Schenectady Tress blown down by severe T'storm 5:25pm
Glenville Schenectady Trees and wires blown down by severe T'storm winds on West Glenville Road and North Road 5:30pm
Margaretville Delaware 3/4" diameter hail 5:35pm
Milton Saratoga Many trees and wires downed by severe T'storm, utility pole with wires down on Route 45 between Rowland St. and Greenfield Ave. 5:35pm
Glenmont and Selkirk Albany Multiple trees blown down in Glenmont and Selkirk 5:49pm
Bennington, VT Bennington Non-T'storm wind gust, measured to 58 mph 6:00pm
Coxsackie Greene Trees blown down by severe T'storm 6:01pm
Accord Ulster Severe T'storm wind damage, trees down 6:06pm
Shaftsbury, VT Bennington Trees blown down by severe T'storm 6:12pm
Pawlet, VT Rutland Severe T'storm measured wind gust of 59 mph with dozens of trees blown down on Tadmer Rd., several as large as two feet in diameter 6:17pm
Petersburg Rensselaer Severe T'storm wind damage 6:20pm
Rhinebeck/Sepasco Lake Dutchess A four mile long, 100 yard wide path of severe tree damage with subsequent damage to many structures that trees fell into caused by estimated 75-80 mph straight line winds, closed roads due to downed trees 6:25pm to 6:30pm
Greenport Columbia Structural damage to a house, with a carport torn off and trees and wires blown down by a severe T'storm wind gust 6:27pm
North Adams, MA Berkshire Measured severe T'storm wind gust of 58 mph 6:36pm
Claverack Columbia Nickel sized hail at the corner of Fish and Game and Route 217 6:36pm
Copake Columbia Trees and wires blown down 6:38pm
Lenox, MA Berkshire Severe damage throughout Lenox into Stockbridge caused by an estimated 80-85 mph straight line wind burst, 300 hundred trees downed at Tanglewood with an estimated $250,000.00 in damage, hundreds of trees downed throughout the area, some into buildings, power knocked out, closed roads due to downed trees 6:57pm
Hinsdale, MA Berkshire Trees down on Ashmere Lake Estimated: Between 6:30 and 7:00pm
Salt Point Dutchess Trees down from severe T'storm winds 7:00pm
Hoosick Rensselaer Non-T'storm wind damage, wires down with numerous power outages 7:00pm
Buskirk Washington Non-T'storm wind damage, wires numerous power outages 7:00pm
Lanesborough, MA Berkshire Severe T'storm wind damage, trees blown down 7:06pm
Norfolk, CT Litchfield Severe T'storm wind damage, trees blown down 7:12pm

This image is a graphical representation generated by the Storm Prediction Center in Norman, OK of the local National Weather Service offices storm reports

SPC Storm Reports for the Decmeber 1, 2006 Outbreak

Rainfall:
Very heavy rainfall was also associated with the passage of the entire weather system from the pre-dawn hours on December 1 through the passage of the squall line during the late afternoon and the evening.

As the chilly air worked south out of Canada after midnight on the 1st, overrunning rainfall developed over the Adirondacks and from Rutland County on north in Vermont. This rain fell continuously at a moderate clip through much of the day in these areas, while areas from the Mohawk valley, Capital Region and Bennington County, VT on south experienced much lighter and scattered showers and drizzle. The squall line event, however, brought torrential rain to much of the region, including the already rain soaked Adirondacks, with rainfall rates up to five inches per hour reported within the line. Fortunately, the torrential rain from the squall line only lasted between five and fifteen minutes at any one location due to the exceptionally fast forward speed of the system. The rapid forward motion of the line precluded a significant flooding situation. As it was, urban and poor drainage flooding occurred in many areas during the height of the heavy rain. However, no major river or stream flooding occurred even across the Adirondacks where the rainfall totals topped 2.5" in many areas for the day.

Table #3 is a listing of the reported storm total rainfall as reported by the CBS6 WeatherNet 6 spotters as well as the Albany National Weather Service Cooperative observers for the December 1, 2006 event. Note: The rainfall totals in all but the Adirondacks, occurred in a mater of ten to thirty minutes.

Table #3

Town

County Rainfall Report Town

County

Rainfall Report

Albany Airport

Albany 0.44" Colonie

Albany

0.36"

North Adams, MA

Berkshire 1.27" Adams, MA

Berkshire

2.00"

Alford, MA Berkshire 0.50" Pittsfield, MA Berkshire 0.54"

Great Barrington

Berkshire 0.32" Savoy, MA

Berkshire

0.39"

Stuyvesant

Columbia 0.62" Livingston

Columbia

0.32"

North Chatham Columbia 1.33" Chatham Columbia 0.50"
Stuyvesant Columbia 1.50" Taghkanic Columbia 0.46"
Margaretville Delaware 0.80"      
Northville Fulton 1.01"      
Millbrook Dutchess 0.81" Poughkeepsie Dutchess 0.48"
Red Hook Dutchess 0.27"      
Catskill Greene 1.03" Tannersville Greene 2.20"
Windham Greene 0.83" Cairo Greene 0.64"
Amsterdam Montgomery 1.25" Sprout Brook Montgomery 0.70"
Glen Montgomery 0.87"      
Piseco Hamilton 2.57" Speculator Hamilton 2.70"
Blue Mountain Lake Hamilton 1.35" Wells Hamilton 1.80"
Stephentown Rensselaer 1.67" Center Brunswick Rensselaer 0.32"
Troy Rensselaer 0.35" Melrose Rensselaer 0.46"
East Worcester Otsego 0.80" Oneonta Otsego 0.50"
Hadley Saratoga 1.23" Saratoga Springs Saratoga 0.83"
Gansevoort Saratoga 1.70"      
Duanesburg Schenectady 0.60" Niskayuna Schenectady 0.48"
Cobleskill Schoharie 0.67" Gilboa Schoharie 0.35"
Richmondville Schoharie 0.81"      
Phoenicia Ulster 1.27" West Shokan Ulster 1.19"
Woodstock Ulster 0.92" Saugerties Ulster 0.60"
Brant Lake Warren 2.78" Bolton Landing Warren 1.00"
Glens Falls Warren 1.41" North Creek Warren 1.01"
Warrensburg Warren 0.64"      
Whitehall Washington 1.97" Cambridge Washington 0.62"