Our attention then turns to a rather potent clipper system, which
will move from the Upper Great Lakes this evening to the Ottawa
Valley by Saturday, with a trailing cold front crossing the eastern
Great Lakes early Saturday morning. The clipper cold front will
produce a burst of snow showers and possibly snow squalls with its
passage. The clipper cold front will become lake enhanced northeast
and east of Lake Erie and Lake Ontario, producing a few inches of
accumulation across Western NY and the eastern Lake Ontario region
late tonight and early Saturday.
Cold air will quickly deepen behind the cold front, with lake
induced equilibrium levels rising to around 10K feet over Lake
Ontario with favorably deep cold air and moisture. The latest model
guidance holds flow westerly over Lake Ontario for roughly 6 hours
on Saturday. Given the favorable thermodynamics and convergence down
the long axis of Lake Ontario, expect a band of heavy lake effect
snow to develop. The band will briefly cross Jefferson County
including Watertown in the morning, then focus on the central Tug
Hill from mid to late morning through late afternoon before moving
south across Oswego County and weakening by early evening. CIPS
analogs, pattern recognition, and high-res guidance suggests the
potential for warning criteria snow amounts on the Tug Hill
Saturday. With this in mind, a Winter Storm Watch for lake effect
snow has been issued east of Lake Ontario.
The clipper will also produce strong wind gusts Saturday. Winds will
peak near the cold frontal passage over and northeast of Lake Erie
Saturday morning, with gusts of 45+ knots possible. Forecast
soundings show enough wind aloft to potentially support a brief
period of low end warning criteria gusts across Western NY, but the
fact that the low begins to fill as it passes our longitude suggests
an advisory event. Regardless, it will be very windy and the
combination of a few inches of snow and strong winds will produce
extensive blowing snow. It will stay windy through the afternoon,
but gusts will come down to around 35 knots or so areawide.