Friday Night-Saturday May 8-9, 2020
Snow Storm - Wind - Cold


A deep snow cover buried the higher elevations surrounding Bennington, VT - Saturday Morning May 9, 2020 - Photograph by Ken Dufresne - 8" of snow reported at an elevation of 1100'.

CLICK HERE FOR THE RADAR PAGE
A SERIES OF RADAR IMAGES DETAILING THE SYNOPTICALLY INDUCED RAIN AND SNOW FROM 7:30PM ON THE 8TH TO 2AM ON THE 9TH

8 Inches of snow in the high elevations surrounding Bennington, VT, Saturday morning May 9, 2020

Snow, wind, and cold opened Mother's Day weekend 2020, a true meteorological May rarity for the region. But, unlike the most recent previous significant May snow event in the record, which occurred on the 18th in 2002, which was not forecast, this event was, with a solid week of notice. Knowing it was coming, however, did not make it any easier to handle especially for the folks in the higher elevations of Washington and Bennington counties where the storm unleashed a surprise by triggering a supercharged upslope event between 3 and 7am after the synoptic (large scale) zone of snow had moved out. Some higher elevation areas in the upslope zone came in with astonishing snowfall amounts ranging from 8"-10" from Argyle to Hebron, Hartford, and Cambridge in Washington County to Shaftsbury, Arlington, Bennington, and Woodford in Bennington County, VT. Snowfall across the vast majority of the rest of the region, however, was far lighter with a trace to under 1" amounts common in most valley areas with anywhere from 1"-4" of accumulation, depending on elevation, in the Catskills, Helderbergs, Taconics, with a few spots in the Adirondacks as well.  The high wind and low wind chills that followed the storm on Saturday were equally as attention getting as the snow was prolonging the feel of winter into early Mother's Day morning on the 10th.

WeatherNet 6 Snowfall Amount and Distribution Map: May 8-9, 2020 - Note: This analysis is a rough estimate of the snowfall across the region and is highly smoothed as the scale of the graphic is not sufficient to resolve the very tight gradients from no snow to many inches of snow due to the sharp elevation differences that occur over short horizontal distances. But, the map does provide a good idea of where heavier vs. lighter snow fell

WeatherNet 6 Observed Snowfall Distribution for the May 8-9, 2020 Event 

Select WeatherNet 6 snowfall reports 

WeatherNet 6 Snowfall Reports May 8-9, 2020
(Does Not Include Any Additional Snow from Snow Showers/Squalls During the Day)

Town County Snowfall Report Town County Snowfall Report
Clarksburg, MA Berkshire 3.5" Becket, MA Berkshire 0.5"
Pittsfield, MA Berkshire Trace Savoy, MA Berkshire 3.7"
           
Knox Albany 1.7" Albany (NWS) Albany 0.1"
Albany (ASOS) Albany Trace South Berne Albany 2"
Rensselaerville Albany 2" Latham Albany 0.4"
           
Taghkanic Columbia 0.3" Ancramdale Columbia 0.1"
Spencertown Columbia 2"      
           
Franklin Delaware 3" Davenport Delaware 4"
Denver Delaware 2.3" Arkville Delaware 3"
           
Broadalbin Fulton 2" Perth Fulton 1"
           
Halcott Center Greene 1.5" Greenville Greene 0.8"
           
Indian Lake Hamilton 4" Wells Hamilton 0.3"
           
Fonda Montgomery Trace Amsterdam Montgomery 0.5"
Palatine Bridge Montgomery 0.3"      
           
Worcester Otsego 2" Oneonta Otsego 1.5" to 2"
East Worcester Otsego 2.2" Cherry Valley Otsego 1"
           
Petersburg Rensselaer 3" Speigletown Rensselaer 1"
           
Ballston Lake Saratoga Trace Galway Saratoga 1.5"
Clifton Park (Oaks) Saratoga 0.3" Saratoga Springs Saratoga Trace
Lake Desolation Saratoga 5.1" Edinburg Saratoga 3"
           
Delanson Schenectady 1" Duanesburg Schenectady 1" to 2"
Rotterdam Schenectady 1"      
           
Jefferson Schoharie 3" Huntersland Schoharie 1.1" to 2"
Richmondville Schoharie 3"      
           
Claryville Ulster 2" Phoenicia Ulster 0.3"
           
Queensbury Warren 0.5"      
           
Hartford Washington 7" to 8" Greenwich Washington 4"
Granville Washington 0.4" Hebron Washington 8.5"
Argyle Washington 8" Salem Washington 6"
           
Woodford, VT Bennington 8.5" West Arlington, VT Bennington 8.8"
Landgrove, VT Bennington 5" Wilmington, VT Windham 0.5"
Danby, VT Rutland 2.5"      

Interestingly, despite a period of light to briefly moderate snow in the Capital Region, which kicked in around 10pm Friday night after the transition from rain was complete and resulted in widespread coating to 1/2" amounts, the official climate reporting site for Albany, which is at the airport, reported only a trace of snow. So, Albany's climate history, which includes only seven measurable snow events on record in May, remained unchanged after this storm.

Antecedent warm conditions, with temperatures well into the 50s during the day prior to the onset of precipitation, coupled with typically warm May ground conditions, and the fairly brief duration of snow (3 hours) which did not fall that hard in the Capital Region, made it difficult for much sticking in the lowest elevations with this storm. The fact, however, that it snowed at all in the valleys, given the time of year, is remarkable in its own right.

All Measurable May Snowfalls on Record at Albany (to date)

Snow falling in Amsterdam, Montgomery County - Friday night May 8, 2020 - Photograph by WeatherNet 6 spotter Chuck Goldy

Amsterdam snow, Friday night May 8, 2020 

LARGE SCALE SET-UP
Unlike the May 2002 snow, which was much more of a mesoscale (small scale) driven event where a combination of a marginally cold air mass which was dynamically cooled further by a period of very heavy precipitation resulting in heavy rain changing to heavy snow in a narrow axis through the Capital Region, this event was rooted in the synoptic scale (large atmospheric scale) and as such could be seen for days in advance, at least conceptually. The main driver was a highly amplified blocking pattern at the jet stream level, in itself not uncommon in the spring. A strong high pressure ridge extended to high latitudes over the North Atlantic (-NAO, North Atlantic Oscillation) which caused the jet stream to buckle over the eastern U.S. allowing colder air to flow south into the Northeast. The high degree of amplification due to the blocking shifted the flow aloft into a strongly cross polar configuration, something much more typical in the winter than in the spring. This cross polar flow aimed the jet up over the North Pole then directly south into the Midwest and Northeast. Embedded within this flow was a tropospheric polar vortex (TPV) (not to be confused with the stratospheric polar vortex which is a permanent feature high up in the atmosphere over the poles.) A TPV is essentially a cut-off pool of very cold air aloft. In this case a TPV broke off from the arctic and was quickly driven south into the Northeast with its fast forward motion allowing little time for the air mass to modify. Its arrival triggered the surface storm which produced the snowfall and ultimately bombed out east of New England going on to produce strong wind and anchor in the cold throughout the Northeast through the 9th.

The graphic below is the 500 mph height anomaly forecast from the ECMWF model depicting the cold core cut-off low (TPV) centered over the Northeast at 2am Saturday May 9, 2020. This height anomaly is around four standard deviations from the mean pattern for May 9, 2020 which makes it an extraordinarily rare cold anomaly for the time of the year.

500 mb height anomaly forecast from the ECMWF model valid 2am Saturday May 9, 2020


The 00z (8pm local time) balloon launch at Albany yielded a new record cold (for the month of May) 500mb (17,000' above ground level) temperature of -40.1° C per the Storm Prediction Center climatology. This temperature broke the previous record for May by 3.4° C, which is a significant margin. No daily records, however, for cold were set at the surface, with Albany's high temperature coming in at 45°, which was two degrees higher than the record low minimum for May 9 of 43° set in 1977. The low temperature of 33° was also considerably higher than the record low for May 9 at Albany which is 27° set in 1956.

Record low 500mb *17,000') temperture at 8pm, May 9, 2020 

SNOW STORM SET-UP
Pretty decent weather preceded the snow through the day Friday May 8 with morning sunshine giving way to clouds and temperatures in the valleys moving into the mid 50s for highs. Dewpoints were low, generally ranging through the 20s which set the stage for wet-bulb cooling when precipitation broke out as light rain west and south of the Capital Region late in the afternoon and early in the evening in response to low pressure developing along a boundary over Pennsylvania. With more than sufficiently cold air aloft already in place to support snow it was just a question of how long it would take for the shallow boundary layer mild air to cool enough for snow to make it down to the ground. As it turned out, it did not take long with five to ten degree temperature drops on average within an hour after the onset of rain. Rain quickly changed to snow early in the evening in the higher terrain west of the Hudson valley with the changeover making it into the Capital Region by about 10pm. Precipitation rates, however, were light to only briefly moderate at times, not high enough to produce heavy enough snow fast enough to overcome the warm ground conditions in valley areas where accumulations were generally 1/2" or less in the lowest elevations. The storm was moving quickly as well which limited the duration of snow to only a few hours at most locations which further reduced the accumulation potential. Most of the snow in the Capital Region fell from 10pm to 1am with flakes at times the size of quarters and half dollars. Higher elevation areas, spots with lower temperatures, bore the brunt of the 1"-4" accumulations that did occur, with the exception of Washington and Bennington counties, which were impacted by a post synoptic scale localized upslope event which greatly enhanced snowfall in that small area.

Surface map around 9pm Friday May 8, 2020 

WASHINGTON AND BENNINGTON COUNTIES UPSLOPE SURPRISE
The synoptic snow shield directly associated with the surface storm had cleared the region by about 2am with no more than patches of light snow or snow showers in the region. By 3am, however, snow began rapidly blossoming again over parts of Washington and Bennington counties as a northwest wind increased due to the storm rapidly intensifying over southeastern New England. Storm position and intensification rate were just right to induce the strong northwest upslope flow in an environment of deep remaining moisture to trigger heavy bands of orographically induced snowfall between 3am and 7am. Snowfall rates in excess of 1" per hour occurred, especially at elevations of 1000' and higher to accumulate 6"-10" of snow on average in localized pockets. Arguably, this small zone of very heavy snow was its own small scale event separate from the widespread light snow directly generated from the storm itself. It is certainly a unique example of how the local terrain often plays a significant role in shaping the impact of passing storms and illustrates why snow forecasts in eastern New York and western New England are so difficult and challenging.

CLICK HERE TO VIEW A SERIES OF RADAR IMAGES FROM 3AM TO 8:30AM SHOWING THE UPSLOPE EVENT

Upslope snow responsible for the heavy accumulations in parts of Washington and Bennington counties between 3 and 7am May 9, 2020 

A deep snow cover in Argyle, Washington County - Photo by Sue McMurry Abrahamson
8" of snow Reported Saturday morning May 9, 2020

8 Inches of snow in Argyle, Washington County, Saturday morning May 9, 2020 

Hartford, Washington County - Photograph by WeatherNet 6 Spotter Dan Johnson - 7" of Snow
Saturday Morning May 9, 2020

7 Inches of snow in Hartford, Washington County, Saturday morning May 9, 2020 

WIND AND COLD SATURDAY MAY 9
The storm bombed out, meaning it rapidly intensified east of New England through the day which caused a tight pressure gradient across the Northeast resulting in strong wind gusts from 40-50 mph throughout the region. With air temperatures topping out only in the 30s in higher elevation areas and low to mid 40s in the valleys, the combination of the wind, limited sunshine with numerous heavy mixed snow and graupel showers from mid morning through the evening, made this May day feel more like early March with wind chills consistently in the 20s to low 30s. The surface map below shows the intense cyclone east of Maine around 3pm with the tight pressure gradient over the Northeast and radar mosaic highlighting the numerous snow and graupel showers/squalls triggered by the intensely cold air aloft and resultant steep low level lapse rates.


Surface map around 3:30pm Saturday May 9, 2020

Wind Advisory county outline map for Saturday May 9, 2020 - Advisory ran from 11am to 8pm

Wind Advisory from 11am to 8pm for much of the region, Saturday May 9, 2020

Wind chills early in the morning dropped to as low as 10 degrees in some higher elevation areas in the Adirondacks, Catskills, southern Vermont and Berkshires where temperatures dipped into the low and mid 20s. Wind chills at Albany ranged from a low of 23° at 8am to a range from the mid 20s to low 30s through the day with air temperatures most of the day in the 30s, only reaching a 40°-45° range between noon and 6pm.

TOWN
COUNTY
LOW WIND CHILL
Pittsfield, MA
Berkshire
11°
Adam, MA
Berkshire
11°
Alford, MA
Berkshire
20°
Great Barrington,MA
Berkshire
25°
Williamstown, MA
Berkshire
24°
Albany (ASOS)
Albany
23°
Colonie
Albany
23°
Voorheesville
Albany
19°
Copake
Columbia
20°
Chatham
Columbia
24°
Hudson
Columbia
26°
Kinderhook
Columbia
21°
Johnstown
Fulton
14°
Gloversville
Fulton
16°
Broadalbin
Fulton
20°
Tannersville
Greene
10°
Freehold
Greene
27°
Piseco
Hamilton
10°
Indian Lake
Hamilton
15°
Little Falls
Herkimer
22°
Hessville
Montgomery
17°
Hagaman
Montgomery
20°
Stephentown
Rensselaer
19°
Troy
Rensselaer
26°
Schodack
Rensselaer
21°
Edinburg
Saratoga
16°
Saratoga Springs
Saratoga
22°
Galway
Saratoga
23°
Clifton Park
Saratoga
26°
Malta
Saratoga
27°
     
Duanesburg
Schenectady
12°
East Glenville
Schenectady
18°
Schenectady
Schenectady
23°
Cobleskill
Schoharie
14°
Glens Falls
Warren
20°
Queensbury
Warren
28°
Granville
Washington
26°
Fort Edward
Washington
24°
Manchester, VT
Bennington
12°
Woodford, VT
Bennington
13°
Bennington, VT
Bennington
19°

Shaftsbury, VT, Bennington County - 6" of snow at the time of the photograph Saturday AM, May 9, 2020
Photograph by Jeannette N Tim Putnam


 

Albany National Weather Service Snowfall Analysis and Distribution Map
The Period Friday Night - Saturday Morning May 8-9, 2020

Albany NWS Snowfall Distribution Map Frida Night-Saturday Morning May 8-9, 2020
 
Averill Park, after some melting, Saturday morning May 9, 2020
Photograph by Deric Gouveia

 

Lake Desolation, Saratoga County May 9, 2020 - 5.1" of snow measured
Photograph by WeatherNet 6 spotter Mindy Noxon

 

Brahman's Corners (Esperance) Schoharie County (1340') - 2" of snow
Photograph by Janette Folckemer

This photograph shows a mass of graupel, which fell from one of the many convective showers that occurred in the wake of the storm through the afternoon and evening on Saturday, May 9. This graupel occurred in Amenia with the photograph proved by Ellen Flanagan. Graupel forms when supercooled water droplet coat or rime falling snowflakes freezing on them turning the snowflake into a soft, almost spongy, often styrofoam looking particle.