A strong weather system will bring some very cold air to
the region. This will produce an accumulating lake effect
snowfall. It begins tonight as rain transitions to snow, then
ends Monday morning. A Winter Weather Advisory is issued for this
snowfall. However, a second weather system will bring another
round of snow Monday evening until Tuesday morning. A Winter
Storm Watch is issued for this snowfall. 

Here's the timeline...

Timing:

Overnight: Rain transitions to snow. Low 29.
Morning: Snow showers and strong winds. Lower 30s.
Afternoon: Mostly cloudy and strong winds. High 35.
Evening: Snow showers and strong winds. Mid 30s.
Monday night: Snow showers and strong winds. Low 32.
Tuesday morning: Snow ends. Winds diminish. Mid 30s.

Here's how much snowfall you can expect for the first round of
snowfall from 10pm tonight to 10am Monday morning:

Around 2-4" of snowfall accumulation for the North Country, a
trace to 1" for the Mohawk Valley, and 1-2" for the Southern
Valleys.

Here's how much additional snowfall you can expect for the second
round of snowfall from 4pm Monday to 8am Tuesday morning:

These amounts are the additional snowfall that will be
accumulated Monday night. Around 3-5" of additional snowfall for
the North Country, a trace to 1" of additional snowfall for the
Mohawk Valley, and 1-3" of additional snowfall for the Southern
Valleys.