As shortwave in the larger scale trough and associated sfc trough
approach on Friday, large scale forcing will result in showers
expanding especially over northern forecast area from Niagara
Frontier running along Lake Ontario and extending to east of
Lake Ontario as lake enhancement will increase. Followed non-
diurnal temp idea on Friday (early highs near 40 with temps
dropping into the mid and upper 30s during the afternoon) which
matched forecast soundings well. Net result is rain/snow showers
becoming more widespread with ptype highly dependant on blyr
temps and elevation as temps aloft will be cold enough for
mainly snow. Higher terrain of WNY and the Tug Hill east of
Lake Ontario figure to keep mix of rain/snow or all snow most of
Friday. Temps will be marginal for much snow accum over WNY
though just a couple degrees of cooling could lead to some more
accums than this forecast shows currently. Meanwhile, it should
stay cold enough on Tug Hill with persistent upslope flow to
result in at least a couple inches of slushy snow on Friday with
best chances later in the day as sfc trough/stronger forcing
draws closer. Farther inland across Southern Tier, conditions
will remain dry until a few rain and snow showers develop later
in the afternoon.
Friday night the sfc trough continues dropping across the region but
deep moisture and larger scale forcing cuts out, so trimmed the pops
down by overnight. Best chances for scattered rain and snow showers
will be over Southern Tier to eastern Lake Ontario region, including
the Tug Hill where another couple inches of snow could still occur.
Later Friday night through Sunday, main focus will turn to the
Nor`easter of which impacts look to stay east of our forecast area
this weekend. Latest ECMWF trended back west slightly, but is also
quite a bit faster. If other models join that trend, then eastern
Lake Ontario region could get clipped by western edge of snow shield
with the system. Just something to keep in mind as we watch model
trends next 24-36 hours. Othewise, NW flow to the west of the
deepening low with deepening cold air aloft will result in plenty of
clouds and some light lake effect snow showers especially southeast
of Lake Ontario this weekend. High temps Saturday and Sunday top out
in the mid 30s most areas, though it will be as cool as the 20s in
the higher terrain east of Lake Ontario. For lows, 20s will be a
common number, though some teens could occur in typical cold spots