Cold air deepened over the eastern Great Lakes with heavy lake snows developing east of Lakes Erie and Ontario.  The wind direction was from the west-southwest for most of the event, directing the heaviest snow into the nearby Buffalo Southtowns off Lake Erie, and areas just south and east of Watertown off Lake Ontario.
Off Lake Erie, during the late morning of the 10th, a weak system approached the lake with well aligned flow becoming established up the length of Lake Erie. The lake effect snow rapidly intensified across the nearby Buffalo Southtowns by midday.  This band of heavy snow then remained nearly stationary through the afternoon and evening of the 10th extending east into northern Wyoming and southern Genesee counties.  There were numerous reports of thunder and lightning within this band for several hours during the afternoon, mostly near the Lake Erie shore just south of Buffalo.  Snowfall rates reached about 3 inches per hour at times during the height of the storm.  Heavy accumulations extended farther inland than normal reaching eastern Genesee and eastern Wyoming counties with moderate accumulations even being reported into western Monroe and northern Livingston Counties.  During the mid to late evening on the 10th the band of heavy lake effect snow moved onshore across all of southern Erie and Chautauqua counties as the wind become more westerly.  This band then spread out into the western Southern Tier and weakened overnight, coming to an end by early morning on the 11th.  Specific snowfall reports included: 22 inches at Alden; 20 inches at Athol Springs; 19 inches at Elma; 17 inches at Orchard Park and West Seneca; 16 inches at Hamburg; 15 inches at Blasdell; 14 inches in Lancaster; 13 inches at Attica; 12 inches at Alden and Wyoming; 11 inches at Wales and Colden; 9 inches at Eden; and 8 inches at Stafford and Corfu.
Off Lake Ontario, lake effect snow developed during the pre-dawn hours of the 10th.  A brief burst of heavy snow crossed the Tug Hill region, followed by a band of moderate to heavy snow that focused mainly on central and southern Oswego County before dawn. By late morning and early afternoon the wind backed to the west and allowed a rapidly intensifying band to center on the Tug Hill region.  Snowfall rates briefly reached two inches per hour during this period as the band crossed the Tug Hill region.  During the late afternoon and early evening winds become WSW just ahead of a weak system approaching the lake.  The band intensified and moved north into the southern portion of Jefferson County and northern Lewis County.  Snowfall rates reached 3 inches per hour during the most intense portion of this storm across the Tug Hill region and areas just south and east of Watertown.  This strong band remained in place through about midnight then moved south and back into Oswego County during the pre-dawn hours of the 11th. The storm came on a weekend, which lessened travel impacts to some extent.  Nonetheless, travel was very difficult during the afternoon and evening of the 10th across the nearby Buffalo Southtowns and the Tug Hill region.
Specific snowfall reports included: 29 inches at Hooker; 24 inches at Rodman; 19 inches at Beaver Falls; 18 inches at Copenhagen and Redfield; 16 inches at Croghan; 14 inches at Constableville; 13 inches at Osceola; 12 inches at Pulaski; 11 inches at Highmarket and Lacona; 9 inches at Lowville; and 8 inches at Oswego.

Lake-Effect Snow in OSWEGO, NEW YORK
From 10-DEC-17 05:00:00 to 11-DEC-17 03:00:00 (EST-5)
Property damage: 35.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Lake-Effect Snow in JEFFERSON, NEW YORK
From 10-DEC-17 05:00:00 to 11-DEC-17 03:00:00 (EST-5)
Property damage: 35.00K
Crop damage: 0.00K
Reported by: Social Media

Lake-Effect Snow in LEWIS, NEW YORK
From 10-DEC-17 05:00:00 to 11-DEC-17 03:00:00 (EST-5)
Property damage: 35.00K
Crop damage: 0.00K
Reported by: Social Media

Lake-Effect Snow in WYOMING, NEW YORK
From 10-DEC-17 06:00:00 to 11-DEC-17 03:00:00 (EST-5)
Property damage: 20.00K
Crop damage: 0.00K
Reported by: COOP Observer

Lake-Effect Snow in SOUTHERN ERIE, NEW YORK
From 10-DEC-17 02:00:00 to 11-DEC-17 03:00:00 (EST-5)
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Lake-Effect Snow in NORTHERN ERIE, NEW YORK
From 10-DEC-17 02:00:00 to 11-DEC-17 00:15:00 (EST-5)
Property damage: 15.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Lake-Effect Snow in GENESEE, NEW YORK
From 10-DEC-17 02:00:00 to 11-DEC-17 00:15:00 (EST-5)
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Trained Spotter