Lake Effect Summary: January 6-8, 2015

Maximum Snowfall: Lake Erie 16.4" (Hamburg); Lake Ontario 23.5" (Watertown)

Duration: 36 hours +/-

Flake Scale: 3 flakes***

The 6^th lake effect snow event of the winter season started on the heels of the 5^th lake effect snow event.  After a brief interruption in lake effect snow bands by the passage of a synoptic shortwave and accompanying light snow, the eastern Great Lakes again formed heavy lake effect snow bands Tuesday evening January 6^th.

Broad cyclonic flow remained over the eastern Great Lakes with temperatures at 850 hPa (5k feet) averaging around -18 Celsius for this event. Lake effect snow parameters were impressive with lake induced equilibrium levels nearing 13k feet off Lake Erie and 16k feet off Lake Ontario. In addition strong convergence into the lake bands brought a rising motion through a saturated snow dendritic growth zone which allowed for ample growth to snowflakes. This event also had several road closures across western New York, including a portion of the New York State Thruway that closed during a period of time. 

Though there was a very cold airmass in place, with a shallow snow dendritic growth zone,  there was a moist, southwest flow that allowed for lake effect snow bands to form Tuesday evening over the North Country east of Lake Ontario, and across southern Erie county east of Lake Erie.  

Off Lake Erie, by Tuesday evening a heavy band of lake effect snow extended across southern Erie and inland across Genesee and Wyoming counties. Snowfall rates approached 2 inches per hour as the band of snow lifted briefly northward towards the Buffalo Southtowns late Tuesday evening. By midnight the steering flow became more westerly and this allowed for the snow band to fall southward, and rapidly decrease in intensity as it reached the southern tier and ski country regions. This snow band remained across the southern portions of western New York through the dawn hours, in a continued weakened state as the westerly flow crossed the now shorter fetch of Lake Erie. There was only a brief increase in snowfall Wednesday morning as a limited upstream connection to Lake Huron was established.  

Off Lake Ontario, a split snow band Tuesday evening eventually consolidated into a single intense snow band. The band of snow lingered over the Watertown and northern Jefferson county areas through the evening, dropping between a foot and two feet of snow. Snowfall rates likely reached 5 inches per hour as this band of snow dropped towards the Tug Hill region late overnight. To the south of the heavy lake effect snow band, lighter snow showers fell over the upslope Tug Hill region, but it was not until a southward dropping arctic front brought the more intense snowfalls southward.

This arctic front crossed the North Country in the predawn hours on Wednesday, January 7th, pushing the lake effect snow bands southward towards Oswego by the morning rush hour. Also, by the pre rush hour, the arctic front was beginning to drop southward from the southern Lake Ontario shoreline, bringing a burst of heavy snow across the northern suburbs of Buffalo and Rochester. This burst of snow, though only a few inches snarled traffic on local roads, and delayed many motorists on their morning commute.

The southward bound arctic front continued to push deeper across western New York through the morning hours, though the intensity of the snows were diminishing as lake moisture waned along the boundary.   

Behind the arctic front, cold northwest flow brought an additional several inches of snow to the southern shoreline of Lake Ontario through the day Wednesday, ending early Thursday morning.     

Here are some representative snow amounts from this event.