On Thursday a trough will dig across the eastern Great Lakes
which will encourage a cold front to drop across the region.
Latest model guidance is in better agreement, with the GFS
trending toward GGEM/ECMWF guidance which have consistently
tracked a wave of low pressure from the lower Mississippi Valley
to southern New England. The surface low will remain well to our
south, but it will provide some synoptic moisture which will
enhance the frontal passage, and then lake effect snow showers
behind the front. There are minor timing differences with the
front, but consensus suggests 850 mb temperatures will drop to
around -10C behind the front Thursday evening, and down to -13C
by Friday morning. This is plenty cold enough to support snow at
all areas, and will bring the first real taste of winter to many
locations.
As is usually the case for our region, the bulk of the snow will
be lake effect (or enhanced). A northerly component post-
frontal flow will not support banding but will provide a general
snow shower regime which will develop Thursday and last
Thursday night and Friday. It`s difficult to pin down amounts in
this flow but advisory amounts of 4+ inches in 12 hours are
definitely in play. The greatest risk for these is across the
western Southern Tier where upsloping and upstream lake
connections will provide enhancement. Regardless of snow
amounts, there is high confidence in much below normal
temperatures with the forecast generally a few degrees cooler
than model consensus blends