A favorable jet streak over southern Ontario Canada will place the
right entrance region over our area, with widespread snowfall
arriving late Sunday night and through the day Monday. Still some
uncertainty with where the greatest snowfall accumulations may lie,
with current thinking in the Southern Tier and into the Niagara
frontier, where 850 hPa frontogenesis will be strengthening. Several
inches of snow will fall by Monday afternoon, with snowfall rates
weakening Monday evening as the upper level jet streak and mid level
moisture pushes northeastward.
However, this lull in the snow intensity will be short lived as a
second and much stronger jet will emerge from the Ohio Valley Monday
night, with the right entrance region of a 180 knot 300 hPa jet
streak passing over our region. Additionally, a shortwave trough
will pass across our region Monday night and into Tuesday. Lower in
the atmosphere a 60 knot LLJ will advance northward along the east
coast, with the left exit region nearing our region. This LLJ will
also aid in deeper Gulf of Mexico moisture transport from the south,
which combined with the increased lift from the shortwave and jet,
could bring heavier snowfall late Monday night and into Tuesday
afternoon. This swath of synoptic snow will likely bring more
significant accumulations to the area Monday night into Tuesday.
There is still sizable uncertainty with the evolution of this event,
in particular with the placement of the strong low level moisture
advection and core of the LLJ. Latest 12Z model guidance has trended
the second wave Monday night further to the southeast--if these
trends hold, the bulk of the heavier snowfall will likely track
closer to the finger lakes region.
Tuesday night, cold air advection embedded in a NW flow may bring
lake effect snow to areas southeast of Lake Ontario. Moisture will
diminish quickly as a spoke of a strong surface high passes across
our region, which will also lower lake inversion heights. As far as
temperatures go for the period, the cold pattern will continue to
hold with highs in the low 20s and upper teens, and lows in the
teens in the evening hours. Tuesday night will be particularly cold,
with overnight temperatures struggling to climb out of the single
digits.