Thursday May 22, 2014
Solitary Supercell - Violent Duanesburg EF3 Tornado

There were few clues in the morning data sets on Thursday May 22, 2014 that conditions would come together to support the development of a solitary and powerful supercell thunderstorm during the afternoon which would go on to produce a violent tornado in the Delanson/Duanesburg area of Schenectady County as well as giant hail ranging in size from 1.5" in diameter (ping pong balls) to a reported 4.0" in diameter (grape fruit sized) on a path from southeast Hamilton County through eastern Fulton, eastern Montgomery, western Schenectady and northern Albany counties between 1:30pm and 4:30pm as the storm moved from north to south, southeast at 20 mph.

Supercell Track From approximately 1:30pm to 4:30pm Thursday May 22, 2014

Supercell Track from 1:30pm to 4:30pm Thursday May 22, 2014

Albany National Weather Service Tornado Report
An at times large single vortex violent tornado up to a quarter mile wide touched down near the intersection of Route 30 and Duanesburg Churches Road in the town of Duanesburg, Schenectady County, tracking for approximately seven miles to where it lifted just southeast of the intersection of Crow Hill Road and Bozenkill Road in the town of Knox in Albany County. Numerous homes, barns, vehicles, trees, and wires were damaged or destroyed along the path of the storm with most of the damage rated EF1 (winds of 86-110 mph.) 10% or less of the damage, according to the Albany NWS, was rated EF0 (winds from 65-85mph.) Violent EF3 magnitude winds (estimated to 140 mph) occurred at one location along Route 20 in Duanesburg where a home was almost completely destroyed.

Estimated Time: 3:33pm to 3:55pm
Maximum EF Rating: EF3: Peak winds 140 mph (violent tornado)
Estimated Path Width: 1/4 Mile
Estimated Path Length: 7 Miles from Duanesburg, NY Schenectady County to Knox, NY Albany County
No Injuries or Fatalities

Tornado Track Graphic: This the tornado track graphic generated by the Albany National Weather Service damage survey team.

Albany NWS Tornado Track graphic from 3:33pm to 3;55pm Thursday May 22, 2014 

Albany Doppler Radar (ENX) base velocity and base relative reflectivity images at 3:42pm and 3:56pm, May 22, 2014. The left image (courtesy of Brian Montgomery, Albany National Weather Service Meteorologist) is a base velocity display showing a strong circulation at 3:42pm as the tornado was moving into Delanson and Duanesburg in Schenectady County. Red colors indicate particles (rain and hail) blowing away from the Albany (ENX) Doppler radar site (located in Berne). Green colors indicate particles (rain and hail) moving towards the radar. The rotational couplet is obvious just Northeast of Delanson on this radar image.

The image on the right is the Albany Doppler radar base reflectivity display at 3:56pm showing an extraordinarily well defined hook echo with strong enhancement to the ball at the end of the hook located just southwest of Duanesburg in this image. That ball was likely a tornado debris ball with the tornado located somewhere in the middle. Debris balls appear on radar as tornadoes loft debris into the atmosphere. This debris, coupled with the rain and hail are highly reflective to a radar resulting in an intense display. Tornado debris balls on radar are rare to see in the Northeast.

Albany Doppler (ENX) velocity display showing a text book strong velocity couplet with the tornadic storm moving into Duanesburg, NY Schenectady County at 3:42pm May 22, 2014 Albany Doppler (ENX) base relectivity display showing a classic hook echo and likely tornado debris ball at 3:56pm Thursday May 22, 2014 

Causal Factors - Storm Set-Up

The following analysis is not purely my own, but rather a collaboration of ideas and theory with Hugh W. Johnson and Steve DiRienzo, both Albany National Weather Service meteorologists, concerning the development of this supercell thunderstorm and subsequent tornado.

Morning/Early Afternoon Set Up

After scattered elevated based downpours and thunderstorms tracked across the region during the early to mid morning hours generally dry weather prevailed with much of the region on the east, or cooler side of a series of fronts slowly approaching from central New York. Only a narrow warm sector of air extended north into south central NY behind a warm front and immediately ahead of a cold front and developing occlusion through the late morning. Cool, stable marine air resided across the region, especially from the Hudson valley on east into New England characterized by generally overcast conditions, temperatures in the 60s and dewpoints in the mid 50s.

Aloft: Cool temperatures prevailed along with diffluent flow, aided by a passing jet streak to the region's north and west, all features supporting upward vertical motion (favorable lapse rates) in the atmosphere. A particularly low freezing level around 9000' was also observed favorable for hail, providing strong enough thunderstorm updrafts could develop.

Instability, however, appeared meager with CAPE, (convective available potential energy - a measure of the potential energy/air parcel buoyancy or fuel for thunderstorm development.) values on the order of 500 j/kg due to cool stable boundary layer air. Low CAPE values generally are not supportive of strong thunderstorm development. (We generally look at CAPE values of 1000 j/kg and higher for severe weather during the warm season.)

Wind: The overall flow in the atmosphere was characterized by strong directional shear (meaning the turning of the wind was significant from the low levels to the mid and upper levels with a southeast surface flow turning all the way to northerly with increasing height.) This directional shear is quite favorable for developing thunderstorm updraft rotation in an environment supportive of thunderstorm updrafts. The speed shear, however, was very weak, generally 10knots or less from the surface to approximately 3500' and up to 15-20 knots above that. These speed shear values fall considerably below thresholds for supporting organized severe thunderstorms.

These data signals all pointed to some thunderstorms forming due to the chilly air aloft and approaching occluded front enhancing surface convergence with hail being the main threat, but not a powerful supercell with subsequent violent tornado. So what happened? The answer most likely lies in the mesoscale and storm scale environment which developed through the afternoon.

Mesoscale and storm scale environment:
Key features which likely contributed to the supercell and subsequent tornado development were as follows:

1) A favorable position of the inbound series of fronts, with a likely triple point of where the occlusion met the cold and warm fronts, over eastern Fulton, eastern Montgomery, and western Schenectady counties during the early to mid afternoon. Boundaries such as these are known to dramatically increase low level helicity (spinning of the air) which if tilted into the vertical and stretched by a thunderstorm updraft can induce that updraft to rotate forming a vortex.

2) This triple point also just happened to be located in a terrain favored area of the eastern Mohawk valley where in southeast surface wind flow scenarios, which this was, low level shear, or turning of the wind, is increased due to the effect the valley has on backing the wind. This backing of the wind and increase in low level shear is favorable for rotational development should a thunderstorm updraft be in that vicinity.

3) Strong differential heating on either side of the boundary occurred. A period of sunshine developed across the southern Adirondacks, Mohawk valley, and western Catskills during the late morning and early afternoon causing substantially more heating than what occurred in the Hudson valley. NWS data shows temperatures climbed well into the 70s with dewpoints approaching 60° in the region near and to the west of where the supercell formed vs temperatures in the mid 60s with dewpoints in the mid 50s at Albany and points east into western New England. The strong temperature gradient over a short horizontal distance contributed to enhancing convergence along the boundary. This convergence, coupled with the chilly air aloft, allowed a strong updraft to form around 1:30pm over southeast Hamilton County.

The national weather service modified the 8pm sounding (00z) from Albany with the higher temperatures and dewpoints that were observed in the Mohawk valley to yield an estimated CAPE value of nearly 2500j/kg, much higher than was anticipated earlier in the day. A 2500 j/kg CAPE is very unstable and supportive of strong thunderstorm updraft development. (A sounding is derived from data measurements taken from weather balloon launches to show meteorological parameters through a vertical slice of the atmosphere along the path of the balloon.)

4) Finally, the storm motion itself, from north to south, likely played a key role in enhancing the low level shear (or turning of the wind) which is critical in tornado development. The storm appeared to form its own storm scale environment allowing it to sustain itself for several hours as it tracked essentially right along the triple point and warm front from southeast Hamilton County into Albany County before weakening after 4:30pm as it tracked into the cooler and more stable marine air to its east. . Extreme turning of the wind relative to the storm motion would have occurred due to the storm's trajectory which likely contributed to the circulation tightening and the tornado forming during the period where the storm was able to ingest the warmer and more unstable air to its west and southwest. Further, as theorized by meteorologists at the Albany National Weather Service, the interaction of the storm's own rear flank downdraft with the strong ESE inflow directly over the the Schoharie Creek valley area likely substantially increased the horizontal spinning of the air directly below the updraft. Local convergences due to these flows interacting over the mouth of the valley may have contributed to this horizontally spinning air to be tiled and stretched into the vertical ultimately forming the tornado vortex.

Summary:

This is a storm that will be studied by meteorologists far smarter than me which will likely yield at some time in the future much greater detail in explanation than what I'm offering here now.

However, the general gist of what happened appears to be this. The combination of a triple point moving into a particularly terrain favored region of the Mohawk valley for increasing low level shear in southeast surface wind scenarios, coupled with strong differential heating on either side of the boundary and the subsequent development of significant instability in this very small pocket in the region came together during a period of peak heating with chilly air aloft and good diffluent flow to support the development of this solitary supercell thunderstorm and subsequent large hail and tornado.

Tornado development is linked in large part to the turning of the wind in the lowest half mile to a mile of the atmosphere in an environment supportive of thunderstorm updraft formation. And it appears clear, that despite weak synoptic scale speed shear, that the mesoscale and storm scale environment, due in part to the positioning of the players, became highly supportive of strong rotation and tornado development at that place and time.

Could this event have been forecast earlier in the day given the morning data sets? I don't believe it could have been, although the indications were there for some thunderstorms with hail, due to the low freezing levels, and that was forecast. The causal factors with this event were strongly rooted in the meso and micro scales which is where weather often falls between data reporting stations and therefore could only be handled through short term nowcasts. However, after it became apparent that strong thunderstorm development was underway, accurate and timely warnings were issued by the NWS from the storm's inception to its dissipation.


Albany Doppler Radar Image Showing the supercell developing over SE Hamilton County near Hope at 1:30pm May 22, 2014. Some rotation was observed with the storm at this time with a hook echo type feature developing towards Upper Benson at this time.


Albany NWS Doppler Radar image at 1:30pm showing the supercell developing over SE Hamilton County near Hope, NY May 22, 2014



Albany Doppler Radar Image Showing the supercell, less defined in appearance over eastern Fulton County at 2:12pm May 22, 2014. Large hail was observed with the storm at this time

Albany NWS Doppler Radar image at 2:12pm showing the supercell over eastern Fulton County, NY May 22, 2014

Albany Doppler Radar Image Showing the supercell, still raged in appearance over eastern Fulton County at 2:27pm May 22, 2014. Large hail was also observed with the storm at this time

Albany NWS Doppler Radar image at 2:27pm showing the supercell over eastern Fulton County, NY May 22, 2014 

PRELIMINARY STORM REPORTS May 22, 2014 (Times are estimates in many cases)

Town County Storm Report Time
Broadalbin Fulton Measured 2.0" diameter Hail 2:30pm
Broadalbin Fulton Measured 3/4" diameter Hail 2:30pm
Broadalbin Fulton Measured 1.5" diameter Hail 2:40pm
Broadalbin Fulton Measured 1.75" diameter Hail Near Route 29 2:41pm
Perth Fulton Estimated 1.25" diameter Hail 2:50pm
Broadalbin Fulton Measured 1" diameter Hail 2:55pm
Perth Fulton Estimated 0.88" diameter Hail 3:00pm
Perth Fulton Estimated 1.25" diameter Hail 3:00pm
Perth Fulton Measured 2.25" diameter Hail 3:00pm
Amsterdam Montgomery Measured 2.0" diameter Hail 3:05pm
Fort Johnson Montgomery Measured 1.75" diameter Hail 3:05 pm
Hagaman Montgomery Estimated 1.0" diameter Hail 3:06pm
Amsterdam Montgomery Estimated 1.0" diameter Hail (Amsterdam High School) 3:08pm
Amsterdam Montgomery Measured 3.0" diameter Hail 3:10pm
Florida Montgomery Measured 1.5" diameter Hail 3:10pm
Amsterdam Montgomery Measured 2.25" diameter Hail 3:10m
Amsterdam Montgomery Measured 2.75" diameter Hail (Frederick Street) 3:12pm
Amsterdam Montgomery Measured 2.00" diameter Hail, fell for 10 minutes 3:15pm
Amsterdam Montgomery Measured 2.00" diameter Hail 3:15pm
2 Miles S. of Perth Fulton Measured 2.75" diameter Hail 3:20pm
Amsterdam Montgomery Measured 4.0" diameter Hail (grapefruit sized) 3:25pm
Amsterdam Montgomery Estimated 1.0" diameter Hail (Julia Street) 3:28pm
Amsterdam Montgomery Measured 1.5" diameter Hail (Near Route 67) 3:30pm
Amsterdam Montgomery Measured 1.0" diameter Hail 3:30pm
1 Mile SSW Scotch Bush Montgomery Measured 1.0" diameter Hail 3:32pm
Duanesburg Schenectady TORNADO: Significant Damage to homes and trees 3:50pm
Princetown Schenectady TORNADO: Tractor trailers flipped on I-88 3:50pm
Princetown Schenectady TORNADO: House collapse 3:50pm
Altamont Albany Wind Damage: Windows blown out of a home 3:55pm
Duanesburg Schenectady Measured 3.00" diameter Hail 4:00pm
Delanson Schenectady TORNADO: Numerous trees down and homes damaged/destroyed along Route 20 4:05pm
Altamont Albany Wind Damage: Home damaged and barn collapsed 4:05pm
Berne Albany Funnel Cloud 4:15pm
New Paltz Ulster Estimated 1.00" diameter Hail 4:52pm

Storm Damage and Hail Pictures - Picture Captions Appear Above the Photographs


Left Photo: Photo Credit: Facebook post from Mike Robinson, giant hail approaching baseball size that fell in Amsterdam, May 22, 2014
Right Photo: Facebook post from Marissa Mattice, hail covering the ground in Hope, Hamilton County
Giant Hail From Amsterdam, May 22, 2014
Hail covering the ground in Hope, Hamilton County May 22, 2014
Left Photo: Photo Credit: WeatherNet 6 spotter Andrea-Nicolella-Clemons, large hail responsible for damage to her car, Amsterdam
Right Photo: Facebook post from Jamie Lemiszki, 2" hail in Amsterdam
Large Hail from Amsterdam
Two Inch Hail in Amsterdam
Left Photo: Facebook post from Mary Bagwell, large hail from Broadalbin, Fulton County
Right Photo: Facebook post from Rich Iwanski, large hail from Amsterdam
Large Hail from Broadalbin, Fulton County
Large Hail from Amsterdam
Left Photo: Photographer: CBS6 reporter Lynne Falsetti, insulation blown into damaged trees in Delanson
Right Photo: CBS6 reporter Lynne Falsetti, tree damage with destroyed house along Route 20 in Delanson in the background
Tree damage in Delanson
Tree damage with destroyed home in the background, Route 20 Delanson
Left Photo: CBS6 reporter Lynne Falsetti, Destroyed home along Route 20 in Delanson, EF3 (Winds of 140 mph) tornado damage
Right Photo: CBS6 reporter Lynne Falsetti, Tree damage along Cole Road in Duanesburg
Destroyed Home along Route 20 in Delanson
Tree damage along Cole Road in Duanesburg
Left Photo: Photographer: CBS6 reporter Lynne Falsetti, Tree damage along Cole Road in Duanesburg
Right Photo: Photographer: CBS6 reporter Lynne Falsetti, more tree damage, uproots, along Cole Road in Duanesburg
Tree damage on Cole Road in Duanesburg
Tree uproots on Cole Road in Duanesburg
Left Photo: Photographer: CBS6 reporter Lynne Falsetti, Tree damage along Cole Road in Duanesburg
Right Photo: Photographer: CBS6 reporter Lynne Falsetti, Tree damage along Cole Road in Duanesburg
Tree damage on Cole Road in Duanesburg
Tree damage on Cole Road in Duanesburg
Left Photo: Photographer: CBS6 reporter Lynne Falsetti, tree damage along Cole Road in Duanesburg
Right Photo: Credit: From Facebook, Greg Duesler, sheared trees near I-88 in Duanesburg, May 22, 2014
Tree damage along Cole Road in Duanesburg
Sheared trees near I-88 in Duanesburg, Schenectady County, May 22, 2014
Left Photo: Photo Credit: From Facebook, Greg Duesler, significant tree damage near I-88 in Duanesburg, May 22, 2014
Right Photo: Credit: From Facebook, Greg Duesler, overturned truck on I-88 near Duanesburg immediately following the tornado, May 22, 2014
Significant tree damage near I-88 in Duanesburg, May 22, 2014
Overturned truck on I-88 in Duanesburg right after the tornado, May 22, 2014
Overturned tractor trailer on I-88 in Duanesburg shortly after the tornado, May 22, 2014. Picture Credit, taken from Elizabeth Alexander on Facebook
Overturned tractor trailer on I-88 in Duanesburg, May 22, 2014 
Photographer: CBS6 Videographer Kenny Mahoney: Duanesburg Volunteer Ambulance Building in Duanesburg, Schenectady County

Duanesburg Volunteer Ambulance Building in Duanesburg, Schenectady County 

WeatherNet 6 Rainfall Reports for May 22, 2014
(Totals Include rainfall from the scattered morning downpours and thunderstorms)

Town County Rainfall Report Town County Rainfall Report
Savoy, MA Berkshire 0.45" Lanesborough, MA Berkshire Trace
Pittsfield, MA Berkshire 0.28"      
           
Westmere Albany 0.22" Voorheesville Albany 1.72"
South Berne Albany 0.25" Preston Hollow Albany 0.63"
Glenmont Albany 0.45" Feura Bush Albany 0.50"
Colonie Albany 0.17"      
           
Livingston Columbia 0.07" Hudson Columbia 0.20"
Chatham Center Columbia 0.24"      
           
Arkville Delaware 0.25"      
           
Broadalbin Fulton 1.50" Gloversville Fulton 0.63"
Fish House Fulton 0.70" Perth Fulton 1.10"
           
Durham Greene 0.34" Catskill Greene 0.09"
Cairo Greene 0.07" Durham Greene 1.00"
Greenville Greene 0.03"      
   
     
Wells Hamilton 1.09"      
           
Glen Montgomery 0.13" Florida Montgomery 0.50"
Amsterdam Montgomery 0.98" to 1.04" Fonda Montgomery 0.59"
           
Oneonta Otsego 0.10" to 0.13"      
           
Center Brunswick Rensselaer 0.08" Grafton Rensselaer Trace
Brunswick Rensselaer 0.20"      
           
Charlton Saratoga 0.30" Corinth Saratoga 0.07"
Milton Saratoga 0.31" Mechanicville Saratoga 0.10"
Wilton Saratoga 0.20" Hadley Saratoga 0.40"
Town of Day Saratoga 0.11"      
           
Scotia Schenectady 0.70"      
           
Jefferson Schoharie 0.50" Charlotteville Schoharie 0.35"
Summit Schoharie 0.07" to 0.12" Middleburgh Schoharie 0.12"
Richmondville Schoharie 0.76"      
           
Kingston Ulster 0.60" Ulster Park Ulster 0.44"
Whiteport Ulster 0.25" Phoenicia Ulster 0.02"
Saugerties Ulster 0.70"      
           
Queensbury Warren 0.05" Warrensburg Warren 0.20"
Brant Lake Warren 0.30"      
           
Cossayuna Washington 0.61"      
           
Landgrove, VT Bennington 0.74" Manchester, VT Bennington 1.20"
Danby, VT Rutland 1.17" West Rutland, VT Rutland 0.10"