Tuesday, May 29, 2012
Widespread Severe Weather Outbreak

A widespread outbreak of severe thunderstorms occurred between 12:30pm and 7:30pm across eastern New and western New England on Tuesday May 29, 2012. The event initiated shortly after a Storm Prediction Center moderate severe weather risk upgrade for the region was made and the issuance of a Tornado Watch which was originally valid from 12:30pm until 9pm for all of upstate eastern New York and western New England with the exception of Otsego, Delaware, Ulster, Dutchess, and Litchfield counties. (It should be noted the Otsego and Delaware counties were covered under a severe thunderstorm watch. Ulster, Dutchess, and Litchfield counties were then subsequently put under tornado watches during the late afternoon.)

The first phase of the event was concentrated over Herkimer, Hamilton, Fulton, Warren, northern Saratoga, Washington and Rutland counties between 12:30pm and 4pm and was comprised of discrete supercellular storms (storms with rotating updrafts) which went on to primarily produce very large hail at times along their paths along with torrential rain and frequent lightning. The mesocyclones (small scale rotating centers) were in general fairly weak and elevated, but at times became stronger, reaching tornado warning thresholds, prompting the issuances of a three short fused tornado warnings. There was no evidence, however, of any tornado touchdowns. One of the issues across the southern Adirondacks, which makes issuing tornado warnings more difficult in this region, is the distance from the Albany radar. The farther from a radar, the higher the beam is in the atmosphere which means warnings are based on a sampling of what's happening four or five thousand feet off the ground rather than at the surface. This requires the meteorologist making the warning decision to extrapolate what may be happening closer to the ground. Nevertheless, considerable hail occurred with locally torrential rain as two and three storms generally moved across the same communities over the few hour period.

The second phase of the event developed as storms expanded further south through the remainder of the Mohawk valley and Capital Region and developed into Otsego and Delaware counties. These storms were more linear in structure, forming into short multicell lines and clusters developing into bowing segments. The severe mode shifted from giant hail to more of a damaging straight line wind and smaller hail scenario, with significant pockets of wind damage in Fulton, Saratoga, and Washington counties reported. The line segment that went through Saratoga County late in the afternoon produced almost continuous lightning and torrential rain in addition to damaging wind and hail up to one inch in diameter. Locally severe multicell storms propagated south into the mid Hudson valley and Berkshire and Litchfield counties, pulling out of Berkshire and Litchfield counties between 7:30pm and 8:00pm ending the event locally.

Instant Doppler 6 Radar Images

4:11pm May 29, 2012

Instant Doppler 6, 4:11pm, May 29, 2012

4:32pm May 29, 2012

Instant Doppler 6, 4:32pm, May 29, 2012 

5:43pm, May 29, 2012

Instant Doppler 6, 5:43pm, May 29, 2012  

Set-Up
A fairly classic set-up for Northeast severe weather was in place to support the event. A warm front had moved through the region during the overnight stalling out over central New England from Vermont to Worcester County, MA and through Rhode Island. This put the region in a hot and oppressively humid air mass as daytime temperatures on the 29th soared into the upper 80s and lower 90s with dewpoints hovering around or slightly higher than 70°. Potential instability also increased through the morning and the afternoon with the benefit of strong heating and a cap (warm layer aloft) which prevented early initiation of thunderstorms. CAPE (convective available potential energy) climbed to between 3000 and 4000 j/kg, which are very high values for the Northeast and indicated a potential for intense and tall updrafts, supportive of severe weather. A cold front and neutrally tiled trough aloft, which produced some modest cooling in the mid levels of the atmosphere, slowly approached western New York with a pre-frontal trough over the west-central part of the state. The pre-frontal trough ultimately acted as the main convergence boundary which lit up as the cooler air aloft broke the cap and allowed thunderstorms to rapidly develop.

Additionally, thunderstorms between 4am and 8am across the southern Adirondacks to Rutland County in Vermont put out small scale outflow boundaries (mini cold fronts) which lingered over that portion of the region through the morning and acted as convergence boundaries firing off the first volley of discrete supercelluar type thunderstorms which developed in advance of the storms firing along the pre-frontal trough over western New York, marking the first phase of the event locally.

The ingredient in the atmosphere that ultimately prompted the issuance of the tornado watch for much of the region was the presence of strong turning of the wind in the low levels of the atmosphere, especially in the Hudson valley and western New England closer to the warm front position. It is this low level turning of the wind that is most supportive of tornado development if other conditions are favorable in the atmosphere to develop deep convection. In this case, however, the magnitude of the wind speeds both at the surface and aloft were generally moderate, not strong. So the overall shear (both the degree of turning of the wind and level of wind speed increase with altitude) was sufficient to support strong organized storm development, but ultimately not strong enough to create an environment which would have supported strong long track damaging tornadoes...and this was known going into the event. The main tornado threat was for very small, short lived, and weak spin-ups, due to the enhanced low level wind shear created by the proximity of the warm front as well as the pressure falls that the developing thunderstorms over west-central New York caused. Those pressure falls created a favorable set-up to induce more of south to southeast wind flow in the north south valleys in eastern New York and western New England, like the Schoharie, Hudson, and Housatonic, which aided in maintaining and slightly increasing the low level shear, or turning of the wind. Ultimately, the severe weather event can be considered moderate in nature, comprised of large damaging hail and damaging straight line winds. Had mid and upper level winds, however, been significantly stronger and the cooling aloft more significant, this event would have been considerably stronger with the severe weather impacting many more communities with stronger gusts and likely a few tornadoes.

STORM REPORTS May 29, 2012

Town County Storm Report Time
Stratford Fulton Estimated 2.50" diameter Hail, (tennis ball sized) 12:49pm
Stratford Fulton Estimated 1.25" diameter Hail, fell for 20 minutes 1:09pm
Caroga Lake Fulton Estimated 1.25" diameter Hail (ping pong ball sized) 1:12pm
North Bolton Warren Estimated 1.75" diameter Hail, (golf ball sized) 1:30pm
Bolton Landing Warren Estimated 2.50" diameter Hail 1:35pm
2 Miles SW of Riverbank Warren Estimated 1.00" diameter Hail 1:40pm
North Bolton Warren Estimated 3.50" diameter Hail (greater than tea cup sized) 1:40pm
2 Miles NE of North Bolton Warren Estimated 1.5" diameter Hail 1:40pm
Edinburg Saratoga Wind Damage, trees and wires down on Oak Road and Route 4 1:57pm
Huletts Landing Warren Estimated 1.75" diameter Hail 2:00pm
Ballard Corners Saratoga Measured 1.75" diameter Hail 2:45pm
Fleischmanns Delaware Estimated 1.00" diameter Hail 4:00pm
1 Mile SW of Pine Hill Ulster Estimated 1.00" diameter Hail 4:00pm
Lake George Village Warren Estimated 1.75" diameter Hail 4:04pm
Lake George Village Warren Estimated 1.25" diameter Hail 4:10pm
Fultonville Fulton Wind damage, trees down on Route 30A south of Fultonville 4:19pm
Tribes Hill Fulton Wind damage, trees down blocking road in front of the Tribes Hill Fire Dept. 4:20pm
Broadalbin Fulton Estimated 1.00" diameter Hail 4:23pm
Gloversville Fulton Estimated 1.00" diameter Hail 4:25pm
Fort Johnson Montgomery Wind damage, trees down at Fulton Montgomery Community College 4:25pm
Cranseville Montgomery Wind damage, trees blown down 4:26pm
Glenville Schenectady Wind damage, trees and wires blown down due to outflow 4:30pm
Galway Saratoga Wind damage, many trees and wires blown down on Hickory Road 4:40pm
Charlton Saratoga Wind damage, tree sheared off at Charlton Heights Elementary School 4:46pm
West Milton Saratoga Estimated 60 mph wind gust 4:50pm
West Milton Saratoga Estimated 1.00" diameter Hail 4:50pm
Factory Village Saratoga Estimated 1.25" diameter Hail 4:51pm
Niskayuna Schenectady Measured 1.00" diameter Hail at GE Global Research 4:55pm
Niskayuna Schenectady Measured 1.00" diameter Hail at CBS6 studios 4:57pm
1 Mile NW of Niskayuna Schenectady Estimated 1.00" diameter Hail 4:58pm
1 Mile SW of Menands Albany Wind damage, Multiple trees blownd down 5:10pm
Saratoga Springs Saratoga Wind damage, trees and limbs down through the city 5:10pm
Cambridge Washington Wind damage, trees blown down 5:10pm
Hoosick Falls Rensselaer Wind damage, trees blown down 5:10pm
Salem Washington Wind damage, trees blown down 5:10pm
Dorset, VT Bennington Wind damage, four trees blown down blocking roads in the village 5:20pm
Mechanicville Saratoga Wind damage, trees and wires blown down 5:33pm
Williamstown, MA Berkshire Wind damage, Multiple trees bown down 5:47pm
Troy Rensselaer Wind damage, trees blown down on Billings Avenue 5:39pm
North Adams, MA Berkshire Wind damage, three trees blown down 5:55pm
South Egremont Berkshire Estimated 1.00" diameter Hail 6:00pm
1 Mile So. of Great Barrington, MA Berkshire Estimated 1.00" diameter Hail 6:05pm
Great Barrington, MA Berkshire Measured 1.00" diameter Hail 6:10pm
Lanesborough, MA Berkshire Wind damage, trees reported to have been blown down 6;11pm
Lafayetteville Dutchess Estimated 1.00" diameter Hail 6:32pm
Pine Plains Dutchess Estimated 1.50" diameter Hail 7:02pm

This is a local storm report map generated at the Albany National Weather Service office, showing the storm reports (severe hail and wind) as well as the severe thunderstorm (yellow) and Tornado (red) warning polygons that were issued by the Albany office for this event.

Local Storm Report Map, May 29, 2012 

This is the Storm Prediction Center (SPC) national severe reports map for May 29, 2012 illustrating the significant number of large hail and damaging wind reports over the Northeast.

SPC National Severe Reports Map for May 29, 2012 

 

Storm Photographs

Left: 1" diameter hail at CBS6, Niskayuna, Nick Johnston, 4:57pm May 29, 2012 - Right: Large hail in Edinburg, Meghan LaPort through Facebook, May 29, 2012
One Inch Diamater Hail at CBS6 in Niskayuna, May 29, 2012
Large Hail in Edinburgh, May 29, 2012
Left: Street Flooding on 8th Avenue in Gloversville at 4pm, Rick Bowers through Facebook - Right: Ominous clouds over Johnstown along Route 30A at 3:56pm May 29, 2012, WeatherNet 6 spotter Paul Wyzomirski
Street Flooding on 8th Avenue in Gloversville, May 29, 2012
Ominous clouds over Johnstown along Route 30A, May 29, 2012
Left: Tree damage in Sharon Springs May 29, 2012 - Right: Shelf cloud segment over Mechanicville, May 29, 2012, both photographs through Facebook
Tree damage in Sharon Springs, Schoharie County May 29, 2012
Shelf cloud segment over Mechanicville, May 29, 2012

WeatherNet 6 Rainfall Reports for May 29, 2012
(Note: Rainfall in most cases fell in one to two hours)

Town County Rainfall Report Town County Rainfall Report
Savoy, MA Berkshire 0.35""      
           
Colonie Albany 1.29" Guilderland Center Albany 1.14"
Glenmont Albany 1.10" East Berne Albany 0.60"
Cohoes Albany 1.37" Latham Albany 1.82"
           
Livingston Columbia 0.98" to 1.18" Austerlitz Columbia 0.50"
Hudson Columbia 0.50" Taghkanic Columbia 0.29"
Craryville Columbia 0.59"      
           
Arkville Delaware 0.83"      
           
Oppenheim Fulton 0.64" Gloversville Fulton 1.29"
Northville Fulton 1.35" Broadalbin Fulton 0.70"
Perth Fulton 0.56" Fish House Fulton 1.00"
Johnstown Fulton 0.36"      
   
     
Round Top Greene 0.30" Catskill Greene 0.35"
Greenville Greene 0.59" Prattsville Greene 0.48"
           
Indian Lake Hamilton 1.20"      
           
Glen Montgomery 0.31" Stone Ridge Montgomery 0.75"
Fonda Montgomery 0.42" Amsterdam Montgomery 0.36"
Hessville Montgomery 0.85" Palatine Bridge Montgomery 0.29"
Fort Plain Montgomery 0.50" St. Johnsville Montgomery 0.40"
           
Worcester Otsego 0.53" East Worcester Otsego 1.16"
           
Center Brunswick Rensselaer 1.06" Brunswick Rensselaer 1.25"
Speigletown Rensselaer 1.30"      
           
Porter Corners Saratoga 1.19" Charlton Saratoga 0.50"
Milton Saratoga 0.69" Ballston Lake Saratoga 0.46"
Mechanicville Saratoga 0.25" Saratoga Springs Saratoga 0.50"
Clifton Park (Oaks) Saratoga 1.39"      
           
Duanesburg Schenectady 0.79"      
           
Richmondville Schoharie 0.95" Jefferson Schoharie 1.00"
Charlotteville Schoharie 0.75" Summit Schoharie 0.33"
           
Kingston Ulster 0.82"      
           
Warrensburg Warren 0.90" Lake Luzerne Warren 1.12"
           
Salem Washington 0.50" Hudson Falls Washington 0.75"
           
Landgrove, VT Bennington 1.25" Woodford, VT Bennington 0.75"
East Wallingford, VT Rutland 2.36" Danby, VT Rutland 0.75"
West Rutland, VT Rutland 0.58"