Lake Effect Summary - November 17-18, 2011

Maximum Snowfall: Lake Ontario 12.5" (West Fulton, NY); Lake Erie 7.5" (Perry, NY)

Duration: 24 hours +/-

Prime feature: Very Cellular, Great Dendritic Snow Crystal Growth, Lightning and Thunder

The 2011-2012 lake effect snow season opened with this marginal event. Snowfall totals were not exceptional, especially given the duration of the event.  However, as often happens with the first storm of the season, it did cause several traffic accidents south of Buffalo off Lake Erie and over portions of Oswego County off Lake Ontario.  In addition, at the edges of the band, winds often are stronger due to low level convergence into the band itself. Wind gusts in excess of 40 mph were observed at Barcelona Harbor on Lake Erie and Oswego Coast Guard on Lake Ontario.  The synoptic scale weather features that produced the band followed the general pattern for lake snows with a 500mb trof that crossed the Great Lakes and provided a period of cold air behind the passage of a cold front.  However, instead of a closed Low at 500mb, it was an open wave that moved fairly rapidly through the Great Lakes. (Fig 1). That same pattern was also evident at 850mb (Fig 2).  As a result we did not maintain prime conditions for an extended period of time.  This led to somewhat meager snowfall totals.  Although the storm duration was listed at +/- 24 hours, it is also a bit deceiving, since it referred to both lakes.  Off Lake Erie, the prime conditions only existed from Thursday evening through early Friday before a strong subsidence inversion built across Lake Erie and cut off most activity.  Elevation played an important role in the snowfall totals and the band actually extended well inland for awhile, dumping snow all the way east into the Western Finger Lakes region. Early in the band history we actually got reports of thunder downwind of Lake Erie.  Off Lake Ontario, it took a bit longer for the cold air to establish itself and also for the winds to line up down the long fetch of the lake.  However, once they did, the combination of a deep boundary layer with convective cells growing to heights of 20,000 ft. and an excellent dendritic growth region for snow crystals, led to a brief period of lightning and thunder across Oswego County.  In fact, the heaviest snowfall totals were not over the traditional Tug Hill Region. Instead, they were located across western Oswego County near Fulton.  The Upper ridge built quickly across Lake Ontario Friday night into Saturday morning ending the lake effect snow.   Radar loops from Buffalo (Fig 3) and Montague (Fig 4) show the snow band at various stages during the event.

All in all this was a nice, gradual way to begin our lake effect snow season, introducing enough snow to remind winter savvy residents that winter is on its way without causing extreme impacts on the public.  Since the impacts on the public were limited but total snowfall exceeded 12 inches in one location, the event earns 2 **  stars.

Here are some representative reports. 

Off of Lake Erie...

Location Snowfall
Perry7.5 inches
Perrysburg6 inches
Glenwood5.5 inches
Randolph5 inches
Franklinville3 inches

Off of Lake Ontario...

Location Snowfall
West Fulton12.5 inches
Highmarket8 inches
Constableville6 inches
West Monroe 4 inches


Fig 1: 500mb Height and 1000-500mb Thickness loop valid 11/17/11 12z through 11/18/11 18z. Fig 2: 850mb Height and Temperature loop valid 11/17/11 00z through 11/18/11 18z. Fig 3: WSR-88D Buffalo 0.5 degree reflectivity loop valid 11/17/11 2217z through 2308z. Fig 3: WSR-88D Montague 0.5 degree reflectivity loop valid 11/18/11 0036z through 0342z.

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