Widespread, Major Severe Weather Outbreak, Tuesday June 10, 2008

A searing early season four day heat wave featuring temperatures in the 90s and dewpoints ranging from the upper 60s to the lower 70s culminated with a widespread regional severe thunderstorm outbreak, which began around 4:30pm as one solitary storm in Otsego County, and ended around 10:30pm with the departure of a large organized squall line from Berkshire and Bennington counties in western New England. Widespread powerful wind gusts produced pockets of damage throughout the region with numerous reports of golf ball sized hail (1.75" diameter). The outbreak affected most of the Northeast with major severe weather reported throughout New England and eastern Pennsylvania with reports of wind damage and hail further south into the mid Atlantic region as well. Figure #1 is the Storm Prediction Center storm reports graphic for the June 10 event, illustrating the widespread nature of the severe weather outbreak.

Figure #1
Storm Prediction Center plot of severe weather reports for the June 10, 2008 outbreak

Set Up:
A high instability (high convective available potential energy 3000-4000 j/kg) and moderately sheared wind environment in mainly speed, set the stage for the outbreak of severe weather on Tuesday June 10. A strong cold front accompanied by an upper air low pressure trough, which spread cooling over the region in the upper atmosphere subsequently increasing the instability, acted as the main trigger and lifting mechanism to get the air rising causing the storms to form. Once storms fired, the high heat and humidity acted as high octane fuel allowing them to rapidly grow to between 40,000 and 50,000 feet allowing their updrafts and downdrafts to interact with and mix down to the ground the stronger winds that were present aloft. (Mean mid level shear ranged from 40-50 knots.) National Weather Service damage surveys in Saratoga, Berkshire, and Litchfield counties indicated straight line winds ranged from 85-105 mph in pockets as a result of both momentum transfer down to the ground from aloft along with accelerations also due to cooling aloft resulting from evaporation along with local terrain effects near the ground.

An anticipated late arrival in the day of the cold front and cooling aloft associated with the approach of the upper level low pressure trough along with a ramping up of the mid level wind speeds through the day lead to the expectation that thunderstorms would time out over eastern New York and western New England between 5pm and 10pm with a consolidated punch of severe weather. And, the main punch of severe weather did in fact time out almost exactly as what had been forecast. However, a round of thunderstorms fired early, during the morning over western New York, which was the one surprise that put the region on alert very early in the day and had meteorologists throughout the Northeast jumping.

After coordination with local northeast National Weather Service (NWS) offices, the Storm Prediction Center was convinced by forecasters in the Burlington, VT NWS office that a tornado watch was necessary for all of upstate eastern New York , Vermont, western MA, and northwest, CT from 10am until 6pm to cover the severe weather potential with the early line of storms. The tornado watch was issued instead of the more common severe thunderstorm watch based on the fact that the low level directional wind shear over the region was thought to be substantial enough to allow any discrete storms earlier in the day to rotate, becoming supercells, which sometimes go on to produce tornadoes. (The wind shear later in the day was anticipated to and did become more unidirectional, more supportive of damaging straight line wind structures rather than tornadoes which is why the main severe event was primarily comprised of damaging straight line winds.) No tornadoes, however, developed with the initial line of storms with much of the activity lifting north of the local area, only affecting Herkimer and Hamilton counties between 12:30pm and 2:30pm with scattered damaging wind gusts. Sinking air developed over the region in the wake of the storms which not only suppressed additional thunderstorm development but also suppressed cloud development allowing temperatures to soar well into the mid 90s under full sunshine, enhancing the amount of potential energy available for later storms to feed off of.

It took until 4:30pm for the combination of the super heated surface air and slight cooling aloft to allow the first updraft to break the cap over western Otsego County allowing the rapid development of discrete severe thunderstorms which quickly became severe producing up to golf ball sized hail. Figure #2 is the Albany NEXRAD radar image from 4:45pm on Tuesday June 10 showing the initial cluster of severe t-storms. These storms were primarily responsible for producing hail ranging from 1.00" to .175" in diameter (up to golf ball sized) in Laurens, Otego, Morris, New Lisbon, Oneonta, and Cooperstown, all in Otsego County between 4:35pm and 4:55pm.

Figure #2: Albany NEXRAD image, base reflectivity, lowest tilt, 4:45pm, Tuesday June 10, 2008

Albany NEXRAD base reflectivity, 4:45pm Tuesday June 10, 2008

Discrete thunderstorm cells expanded north into the Mohawk valley and southern Adirondacks, through 5:30pm, with damaging storms developing into Saratoga and Washington counties through 6:30pm with much of the remainder of the region dry, with the exception of eastern Greene County, where an isolated severe thunderstorm developed. In Saratoga County, a particularly nasty storm tracked through the south-central portion of the county affecting Malta, Saratoga Lake, Schuylerville, and Ballston Spa with hail up to golf ball size and estimated damaging winds ranging from 80 to 100 mph resulting in many downed trees and power lines with damage to cars and homes due mainly to the falling trees. Figure #3 is Albany NEXRAD image of the damaging Saratoga County storm.

Figure #3: Albany NEXRAD image, base reflectivity, lowest tilt, 6:37pm, Tuesday June 10, 2008. A slight hook echo can be seen on the western most storm in the image indicating a mid level sustained rotating updraft at this time. This was the cell responsible for the estimated 85-100 mph straight line winds that created much of the damage across southern Saratoga and southern Washington counties through evening, prior to the main thunderstorm event.

Albany NEXRAD base reflectivity, 6:37pm Tuesday June 10, 2008 

Click here for additional radar and storm damage images  

The main thunderstorm event swept from west to east across the region moving between 30 and 40 mph, just in advance of the cold front, between 7pm and 10:30pm coming in the form of short lines and clusters of storms which eventually consolidated into a substantial squall line. The main round of storms produced vivid frequent lightning, hail up to 1.00" in diameter and widespread strong to damaging wind gusts as well as briefly torrential rain. The fast forward motion of the storms, however, prevented excessive amounts of rain at any one location with amounts generally ranging from 1/2" to 1" under the heaviest activity. As the line moved through Otis, MA in Berkshire County, an estimated 85-105 mph straight line wind gust (estimate based on a NWS storm damage survey) produced destruction to mainly trees and utility poles between 9:45pm and 9:55pm. Large hail or wind damage was reported in almost every county in the WRGB coverage area resulting from the outbreak. No tornadoes formed with this event as the change in direction of the wind (directional shear) was not significant enough to get the discrete storms to spin fast enough or long enough to drop any twisters. The back edge of the squall line cleared Berkshire, Bennington, and Litchfield counties by 10:30pm with showers lingering through midnight.


This table is a listing of the severe weather reports for the June 10, 2008 severe weather event published by the National Weather Service. Storm reports are collected by the NWS for the purpose of verifying the warnings that were issued and do not reflect the total amount of damage that may have occurred in the region, only what was reported.

Town

County Severe Weather Report

Time

Near Moshier Falls

Herkimer Numerous trees blown down 12:40 pm
Old Forge Herkimer Wind damage, trees and wires blown down 1:00 pm
Mckeever Herkimer Tree blown down on a house 1:05 pm

Lake Pleasant

Hamilton Trees and power lines down, blocking numerous roads 2:10 pm
Arietta Hamilton Two trees blown down, wires down 2:10 pm
Indian Lake Hamilton Trees and power lines down 2:10 pm
Laurens Otsego Hail: 1.25" (Half dollar sized) 4:35pm
Otego Otsego Hail: 1.75" (Golf ball) 4:40 pm
Morris Otsego Hail: 0.75" (Penny sized) 4:40 pm
New Lisbon Otsego Hail: 1.00" (Quarter sized) 4:40 pm
Oneonta Otsego Hail: 1.25" 4:43 pm
Cooperstown Otsego Hail: 0.88" (Nickel sized) 4:45 pm
Richfield Springs Otsego Hail: 1.25" 5:40 pm
Near Burnt Hills Saratoga Wind damage: three trees reported blown down 5:50 pm
Near Ballston Spa Saratoga Hail: 1.75" 5:55 pm
6 miles NNE of Scotia Saratoga Hail: 1.00" and wind damage, branches and trees down 6:09 pm
Ballston Spa Saratoga Hail: 1.00" 6:13 pm
Round Lake Saratoga Hail: 1.00" 6:13 pm
Saratoga Springs Saratoga Major wind damage, Route 9P closed from Route 76 to the city of Saratoga Springs due to major damage to trees and utility poles (estimated 80-100 mph straight line winds based on NWS storm damage survey) 6:15 pm
Old Forge Herkimer Wind damage, trees and lines down 6:30 pm
Russia Herkimer Wind damage, trees and wires down 6:30 pm
Stillwater Saratoga Hail: 1.75" 6:37 pm
Greenwich Washington Hail: 1.00" 6:39 pm
Granville Washington Wind damage, pig house blown over on a farm 6:46 pm
Herkimer Herkimer Wind damage, trees, wires, and transformers blown down 6:46 pm
Catskill Greene Hail: 0.88" and wind damage, trees and branches down 6:50 pm

Salem

Washington Wind damage and large hail, branches down 6:51 pm
Rupert, VT Bennington Hail: 0.88" 6:55-7:00 pm
Catskill Greene Wind damage, trees and lines blown down 6:55 pm
West Rupert, VT Bennington Wind damage, trees and wires blown down 7:00 pm
Poland Herkimer Trees and wires blown down along Route 8 7:05 pm
Piseco Hamilton Trees blown down 7:10 pm
Caroga Lake Fulton 100 foot maple tree blown onto power lines 7:30 pm
Franklinton Schoharie Trees blown down along SR 145 8:13 pm
Schoharie Schoharie Trees blown down along SR 443 8:13 pm
Mindenville Montgomery Fire caused by lightning 8:15 pm
Perth Fulton Wind damage, trees blown down 8:17 pm
Granville Washington Hail: 0.75" 8:40 pm
Colonie Albany Estimated 60 mph t-storm wind gust 8:50 pm
Arkville Delaware Wind damage to utility poles 8:50 pm
Hoosick Falls Rensselaer Wind damage, trees blown down 9:04 pm
Manchester, VT Bennington Wind damage, several trees blown down 9:15 pm
Saint Remy Ulster Trees and wires blown down 9:20 pm
Canaan Columbia Hail: 0.75" 9:24 pm
Pittsfield, MA Berkshire Trees and wires blown down 9:36-9:41 pm
Egremont Plain Berkshire Wind damage, trees and wires down 9:40 pm
Otis, MA Berkshire Hail: 0.88" to 1.00", and significant wind damage 9:47 pm
Cannan, CT Litchfield Wind damage, trees and wires blown down 9:55 pm