Model guidances continue to have their difference with placement and
timing of features for the weekend and into the first half of the
next week, therefore forecast confidence remains uncertain.
The upper level low over the western Great Lakes Saturday morning
will allow for a shortwave to round eastern edge of the low, which
will help pull the low northeastward. As this shortwave rounds into
the eastern side of the low, it will enter into an area of vorticity
along the Atlantic Coast which will help form a surface wave along
the cold frontal boundary. This newly formed surface wave will
deepen as energy is transferred from the primary surface low located
over the western Great Lakes. The newly strengthening low will then
make its way north crossing the Green and White Mountain ranges
Saturday night. Meanwhile, the remnants of the surface low over the
Great Lakes will make its way over the eastern Great Lakes during
this time, before advancing northeast on Sunday. Additionally, in
the wake of the cold front, cold air will be advected into the
region, with air aloft at 850mb dropping to -8/-10C.
All in all, what does this mean in terms of weather for the region?
Saturday morning, the precipitation associated with the frontal
passage from the night prior will be along eastern portions of the
region (Northern Cayuga/Oswego counties eastward). This area of
precipitation should remain overhead across the eastern portions for
much of the day Saturday as the aforementioned surface low over the
Atlantic Coast tracks northward across Vermont and New Hampshire.
Much of this precipitation should fall in the form of snow, though
in the lower elevations some rain/snow mix and eventually all rain
will be possible due to diurnal heating. For the remainder of the
region, chances for snow/mix of snow and rain/rain showers remain in
the forecast due to wrap around moisture and remnants of the primary
low crossing the area.
Lake effect snow showers will form due to a combination of the
cold air aloft crossing the lakes though this won`t be until
late Saturday and Sunday night. There will be marginally cold
enough lapse rates for lake snows, but with lake induced
equilibrium levels reaching 5 to 8K feet, as winds align
Saturday night and into Sunday, decent plumes of lake snows are
possible, especially east of Lake Ontario where lapse rates will
be slightly steeper.
Possibility of lake snows will remain in the forecast through the
first part of the new work week as model guidances are slower to
build in the surface ridge into the area.