Tuesday-Thursday, March 13-15, 2018
Moderate Nor'easter (13th)
Hybrid Intense Mohawk-Hudson Convergence Event ( Late PM/Eve. 13th)
Heavy Upslope Snow Event (14th-15th)

Spectacular GOES-EAST High Resolution 0.5km Visible Satellite Image - 2pm Tuesday March 13, 2018
Intense cyclone centered several hundred miles ESE of Cape Cod and the Islands


High resolution GOES-EAST visibile Satellite Image around 2pm Tuesday March 13, 2018

This was the third major Nor'easter to strike the Northeast in less than two weeks with severe impacts again for central and eastern New England with snowfall ranging from one to two feet through much of central and eastern MA, CT, RI, NH and Maine along with near hurricane force gusts over the outer Cape and the Islands with a verified blizzard along the coasts of Maine, NH, and MA including the City of Boston. The central pressure in the storm dropped over 24 millibars in 24 hours classifying it as a "bomb" with the reading at 968 mb at 11pm on the 13th.

This storm, however, unlike the first two, evolved and tracked much farther east and south of the local area, further off the coast, which, had it been a more ordinary system with smaller spatial coverage, would have lead to minimal impacts across eastern New York and far western New England in terms of snowfall. However, the storm was huge with an enormous circulation and was coupled with a strong upper level low approaching from the Midwest. The combination of the two systems delivered a moderate 3"-6" snowfall on average by 11pm across the region (a glancing blow compared to the large central and eastern New England snow totals) with heavier amounts across eastern Bennington, eastern Berkshire, and eastern Litchfield counties where the far western heavy snow bands from the coastal bomb reached briefly mainly during the morning.

There was a local snowfall jack pot, however, centered in and near the Capital Region, where intense small scale banding developed during the mid to late afternoon and continued well into the evening with snowfall rates of 1" to at times 2" per hour leading to a small strip of greatly elevated snow accumulations ranging from 7"-12" by midnight, roughly double what the majority of the region received.

WeatherNet 6 Snowfall Amount and Distribution Analysis For Phase I of the Storm - Tuesday , March 13, 2018

WeatherNet 6 Observed Snowfall Distribution for phase I of the storm on Tuesday March 13, 2018 

Zones of Enhanced Snowfall Tuesday March 13, 2018

Localized heavy snow zones which occurred during phase I of the storm on Tuesday March 13, 2018

There were a complex set of features in the atmosphere over the Northeast during the late afternoon and evening of the 13th including an inverted surface trough, which extended from the storm center located well off the New England coast, along with an upper level deformation zone (a region of stretching in the atmosphere where air of different origins converges toward each other then fans out as they meet creating a region of lift favorable for heavy precipitation.) The deformation zone was caused by the position of a strong upper low off the New England coast as well as a strong upper low over the Midwest with those two systems likely interacting with each other to produce enhanced upward vertical motion in the atmosphere over eastern New York which was further enhanced by the location of the surface trough.. The surface map below illustrates the rough position of the inverted surface trough and a rough idea of the surface wind direction at approximately 9:30pm, March 13, 2018. The narrow zone of moderate to heavy snow is circled in yellow.

Local surface map showing the position of an inverted surface low pressure trough and the rough direction of the surface wind at approximately 9:30pm, March 13, 2018

It would appear, that at least initially as local convergence increased, two distinct small scale (mesoscale) bands of heavy snow developed around 4pm, one (shorter lived) extended from Fulton county, through eastern Montgomery, western Schenectady and western Albany counties with the other (the dominant band) across southern Saratoga, eastern Schenectady, eastern Albany and western Rensselaer counties. This occurred within the broader area of light snow which had been falling across much of the region through the day.

The image below is from the Albany Doppler radar. It's a base reflectivity image, lowest tilt, at approximately 5:30pm showing two distinct areas of heavier snow, illustrated by the darker shades of green over western and eastern Schenectady counties as well as across southwest Saratoga, eastern Schenectady and northeast Albany counties. Very light snow was falling at this time at both Schenectady and Troy, on either side of the band, with heavy snow just short distances away at Niskayuna, Colonie and through downtown Albany.

Albany Doppler Radar Image, approximately 5:30pm, March 13, 2018 

Through the evening, the dynamics of the situation appeared to change as the western heavy snow band tended to dissipate fairly quickly or even merge with the eastern heavy snow band which took over and intensified with snowfall rates briefly reported as high as 2"/hour. The radar picture below, at approximately 8:30pm, illustrates the darker green shades, indicating heavy snow concentrated over eastern Schenectady, southern Saratoga, northeast Albany and western Rensselaer counties. This band of snow ultimately stretched well into central Columbia County before the support for it weakened with the snow rapidly diminishing between 11pm and midnight.

Albany Doppler Radar Image, approximately 8:30pm, March 13, 2018 

THERE WAS MORE - Hybrid Mohawk-Hudson Convergence
The convergence and subsequent lift caused by the surface trough as well as the upper level venting due to the deformation zone, although apparently instrumental in the development of the small scale heavy snow bands, were probably not enough for the maintenance and intensity off the primary band as it evolved over the Capital Region. It appears that there was some help from the well researched local Mohawk-Hudson Convergence phenomenon (MHC.) An MHC is a phenomenon that will sometimes occur in and around the Capital Region in any season, but most impactful during the winter, if a number of conditions are met with critical parameters including a northerly wind down the Hudson valley converging with a westerly or west to northwest wind down the Mohawk valley in an environment of high moisture and relatively weak dynamics aloft. Although these conditions were not exactly met, it would appear that there was enough of a convergence of the wind, NNW to NW down the Hudson valley and WNW down the Mohawk valley, within a region where the air was already readily rising, to allow for a robust response in an intense long lived narrow heavy snow band which dropped heavy snow from approximately 4pm through midnight and due to its long duration significantly elevated the snowfall totals by about double across southwest Saratoga, eastern Schenectady, eastern Albany, western Rensselaer and northern and central Columbia counties. Temperatures aloft had also cooled allowing excellent snow crystal growth, as the zone of lift occurred in a good snow growth region of the atmosphere (mid level temperatures from -12° C to -17°C) allowing for large efficiently accumulating snow flakes to occur in the narrow zone.

With snowfall through the majority of the day light in intensity and temperatures again with this storm hovering from 32° to 34° in the Capital Region, coupled with it being March, generally wet roads resulted with limited travel issues through the daylight hours. However, after dark and in the bands of heavier snow, temperatures dropped to freezing or a little below with the heavy snowfall rates overcoming any warm road surfaces resulting in snow covered roads and very slick conditions which developed quickly. Multiple accidents were reported on the northway in Saratoga County, among other roads, due to the fast accumulation of snow and greatly reduced visibility during the evening.

Snowfall largely broke up and dissipated throughout the region, becoming very light and intermittent between 11pm on the 13th and 2am on the 14th marking the conclusion of the first phase of the storm and the end of any additional significant accumulations in the Capital Region-Hudson valley. Phase II of the storm, however, got underway prior to daybreak on the 14th and resulted in significant additional snowfall across the higher elevations both east and west of the Hudson valley due to a steady state upslope flow pattern in an environment of high moisture in a cold cyclonic flow. (Upslope precipitation is caused in an environment of blocked flow where the air is forced to ascend as it encounters elevated terrain. The additional lift that is produced by the interaction of the wind and the mountains is the mechanism which produces precipitation and in the winter that precipitation often falls as snow. This process is largely why higher elevation locations, plus the fact these locations are generally colder, often receive greatly elevated snow accumulations when compared to nearby valley locations.)

Because of the significant blocking at the jet stream level downstream of the storm (the pattern that had characterized the month to date) the storm, like the previous two nor 'easters, was also prevented from moving away. Instead, it was forced to curl up across Maine then into eastern Canada where it sat through the 15th. The steady state strong west to northwest flow that resulted effectively upsloped across the higher elevations through the Adirondacks, Catskills, Green mountains in Vermont, the Taconics and the Berkshires producing additional moderate to heavy amounts of snow through the 15th, with the most efficient snow production across the higher elevations in Vermont and the Berkshires where snow, although lighter in intensity, continued into the morning of the 16th. Snow totals in some higher elevation spots in the Catskills and Schoharie County (2000' and higher) piled up to 15"-20" with anywhere from two to four feet in the mountains across southern Vermont. In fact, an astounding 50 " of snow fell (through 12pm on the 16th, a three day total) on top of Woodford, Mt. VT at an elevation of approximately 2300' with the snow not completely ending in the Vermont upslope areas until Friday evening, March 16.

Select Multi-Day Snowfall Reports

Town County Snowfall Report
Woodford, VT (2300') Bennington 50" (12pm/16th)
Landgrove, VT (1888') Bennington 27" (12pm/16th)
Manchester, VT (930') Bennington 20.4" (7am/16th)
Danby, VT (1868') Rutland 18" (6am/16th)
Jefferson Schoharie 16.8" (5am/15th)
Lenoxdale, MA Berkshire 15.8" (8:23am/15th)
Worcester (2000') Otsego 13.5" (4:30pm/15th)
Arkville Otsego 13.3" (11pm/14th)
Cherry Valley Otsego 12.5" (4:30am/15th)
West Rutland, VT Rutland 12" (5pm/14th)
Richmondville Otsego 12" (4am/15th)
Albany (Airport) Albany 12" (8pm/14th)
Franklin Delaware 11.5" (5am/15th)
New Marlborough, MA Berkshire 11" (5pm/14th)
Charlotteville (1627') Schoharie 10.8" (4:30am/15th)
Clifton Park (Oaks) Saratoga 10" (1am/14th)
Latham Albany 10" (11pm/13th)
Clarksburg, MA Berkshire 9.8" (6am/15th)
Oneonta (1440') Otsego 9.6" (5pm/15th)
Warnerville (1484') Schoharie 9.5" (12pm/15th)
Becket, MA Berkshire 9" (5pm/14th)
Knox Albany 8.7" (12pm/14th)
Ancramdale Columbia 8.2" (6pm/14th)
Colonie Albany 8.2" (6am/14th)
Glenville Schenectady 8" (6pm/14th)
Indian Lake (1849') Hamilton 6" (5pm/14th)
Wells (1232') Hamilton 6" (12pm/15th)

Photograph Contributed by Christopher Wright for the Bennington Blotter: Woodford Lake Estates at Woodford, Mountain, VT Bennington County, buried in feet of snow - March 15, 2018

National Weather Service Storm Advisory Board 

WeatherNet Snowfall Reports, Largely For Phase I of the Storm, Through 8am March 14, 2018
(Time and Date of the Report is Indicated)

Town County Snowfall Report Town County Snowfall Report
Clarksburg, MA Berkshire 4.8" (6am/14th) Becket, MA Berkshire 6" (5pm/13th)
Savoy, MA Berkshire 9.7" (11pm/13th) Canaan, CT Litchfield 6" (5pm/13th)
Knox Albany 7.3" (11pm/13th) Albany (NWS) Albany 6.7"
Albany (Official) Albany 12" Colonie Albany 7.5" (10pm/13th)
Taghkanic Columbia 5.1" (11pm/13th) Chatham Columbia 9" (11pm/13th)
Austerlitz Columbia 11.5" (11pm/13th) Ancramdale Columbia 6" (6pm/13th)
Denver Delaware 6" (11pm/13th) Arkville Delaware 6.8" (11pm/13th)
Perth Fulton 5.8" (8am/13th) Broadalbin Fulton 4" (7am/14th)
Gloversville Fulton 4" (4am/14th)      
West Kill Greene 8" (11pm/13th) Halcott Center Greene 5.5" (7am/14th)
Catskill Greene 3.3" (6pm/13th) Cairo Greene 4.8" (6pm/13th)
Greenville Greene 6" (5am/14th)      
Wells Hamilton 4.8" (8am/14th) Hoffmeister Hamilton 6" (5pm/13th)
Indian Lake Hamilton 4" (5pm/13th)      
Florida Montgomery 6.3" (11pm/13th) Amsterdam Montgomery 6" (6am/14th)
Fonda Montgomery 4.7" (8am/14th) Palatine Bridge Montgomery 7.5" (5am/14th)
East Worcester Otsego 8.5" (6am/14th) Cherry Valley Otsego 9.5" (4am/14th)
Worcester Otsego 5.5" (5pm/13th) Oneonta Otsego 4.3" to 5" (11pm/13th)
Petersburg Rensselaer 4.5" (11pm/13th) Center Brunswick Rensselaer 5.5" (11pm/13th)
Speigletown Rensselaer 5" (6am/14th)      
Saratoga Springs Saratoga 3" (11pm/13th) Galway Saratoga 7.2" (7am/14th)
Clifton Park (Oaks) Saratoga 10" (1am/14th) Malta Saratoga 4" (10pm/13th)
Lake Desolation Saratoga 7.6" (5am/14th)      
Rotterdam Schenectady 5" (11pm/13th) Niskayuna (CBS6) Schenectady 9" (1am/14th)
Delanson Schenectady 10" 6pm/13th) Duanesburg Schenectady 8" (7am/14th)
Schoharie Schoharie 3.3" (11pm/13th) Gilboa Schoharie 8" (11pm/13th)
Jefferson Schoharie 6" (6am/14th) Huntersland Schoharie 7.5" (5am/14th)
Richmondville Schoharie 7.3" (3am/14th) Warnerville Schoharie 5.5" (8am/14th)
Saugerties Ulster 1.8" (7pm/13th) Phoenicia Ulster 5.1" (6pm/13th)
Whiteport Ulster 1.5" (5pm/13th) Esopus Ulster 1" (5pm/13th)
Highmount Ulster 10" (8am/14th)      
Warrensburg Warren 4.5" (7am/14th)      
Cossayuna Washington 7" (8am/14th) Hudson Falls Washington 2.2" (6am/14th)
Landgrove, VT Bennington 13" (11pm/13th) Woodford, VT Bennington 13" (6pm/13th)
E. Arlington, VT Bennington 5" (5pm/13th) Manchester, VT Bennington 2.5" (5am/14th)
Danby, VT Rutland 6.8" 6pm/13th) West Rutland, VT Rutland 4" (5pm/13th)

Albany National Weather Service Snowfall Analysis and Distribution
The Period Monday March 12-Thursday March 15, 2018

Albany NWS Cumulative Snowfall Analysis of the March 13-15th, 2018 Event