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fxus61 kbgm 231958 
afdbgm

Area forecast discussion
National Weather Service Binghamton New York
258 PM EST Mon Jan 23 2017

Synopsis...
a storm will track up the East Coast through Tuesday.
This system will bring heavy wet snow and sleet to central New York and
parts of northern Pennsylvania. After this storm system passes,
a weaker trough moves through Wednesday with a chance for a light
wintry mix Wednesday morning.

&&

Near term /through Tuesday/...
10 am update...the main change was to delay onset of precipitation
by a couple hours as it continues to trend slower to move
in...currently, leading edge just encroaching NE PA zones but
temps still mild enough this should be mainly rain. No other
changes to forecast at this time beyond this afternoon as new
guidance just beginning to arrive.



Previous discussion...issued a Winter Storm Warning from 1pm
today to 1pm Tuesday for all of central New York and the northern
tier of Pennsylvania. Issued a Winter Weather Advisory from 1pm
today to 1pm Tuesday for Luzerne, Lackawanna, southern Wayne and
Pike counties in northeast Pennsylvania and Sullivan County in New
York.

A vertically stacked system will move through North Carolina today
then move off the coast this evening and track northeast along the
coast to around coastal New Jersey. By Tuesday afternoon the
system will be lifting well out to sea.

Models continue to be in fair agreement with the position and
movement of this winter storm but differnces still exist in the
thermal profiles and resulting precipitation type. The Canadian
continue to be the coldest with the GFS/European model (ecmwf) fairly close but the
European model (ecmwf) is slightly cooler. The NAM this run came in the warmest
implying less snowfall. For this forecast leaned toward the
cooler/consensus forecast as the NAM appears to be the outlier.
Unfortunately slight errors of around 1c in the low levels will
have huge consequences with precipitation type and resulting
accumulation.

Rain will spread from south to north today with timing slower
than the previous run. Colder air will advect across the area from
east to west as colder air associated with high pressure in Quebec
gets drawn into the system. Precipitation type will likely
transition from rain to sleet then snow. Strong lift will move
through the area overnight with dynamic cooling continuing this
transition to snow/sleet mix. The last area to change to a wintry
mix will be The Finger lakes. Bulk of precipitation will occur
overnight with heavy periods of snow and sleet likely. Freezing
rain is a possible but not a high probability. Strong winds later
this afternoon through the overnight period in combination with
heavy/wet snow could lead to power outages.

In generally warning area will see 4 to 9 inches of heavy wet snow
and sleet with the advisory area 3 to 5 inches. The greatest
accumulations are expected in the higher terrain. Used a snow to
liquid ratio of 10/1 in the higher terrain and 8/1 elsewhere.

The wintry mix will end from west to east Tuesday afternoon as the
system lifts well out to sea. In valley areas the precipitation
could mix back with plain rain as the boundary layer warms
especially in the valley areas and northeast Pennsylvania and
Sullivan County. Less snow is expected in the advisory area due to
more sleet and rain. Both the GFS/European model (ecmwf) show warmer air moving
back into the region Tuesday morning as the system lifts to
coastal New Jersey.

&&

Short term /Tuesday night through Thursday night/...
300 PM update...
exiting low pressure just off the coast of New England and trailing
upper trough in the eastern Great Lakes will allow the snow and
possibly sleet to persist Tuesday night and early Wednesday morning.
Snow amounts should be light, as the mid/upper levels dry out
quickly with high pressure building in from the west. The overall
trend Wed morning will be drier with slightly warmer temperatures
into the upper 30s and lower 40s. The ridge will very quickly shift
to the east, but the warm air will linger a bit as a pre-frontal
trough lifts ewd through the region. This trough will act to product
scattered rain showers later in the day Wednesday and Wed night.

Thursday will be a transition day with the colder air moving in
slowly from the west. As 850mb temps drop to -2 to -4 deg c...the
rain will begin to mix with snow...especially in the higher
elevations through thur afternoon. The mix of rain and snow will not
result in much snowfall accumulation...and only a trace to around a
couple tenths of an inch of liquid...with the highest rainfall amts
expected in central New York.

&&

Long term /Friday through Monday/...
300 PM update...
there will be a noticeable cool down Thursday night as 850mb temps
cool to -8 to -10 deg c. Surface temperatures will fall into the mid
20s. This strong push of cold air from the northwest will induce weak lake
effect bands off Lake Ontario...with the primary area of
accumulating snow expected near the thruway and north. It is still
too early to define snow amounts, but several inches are possible
through the end of the week. The air mass will become slightly
cooler...around -12 deg c later in the day Friday...which may
enhance or allow the snow band to become better defined. There is
some variation in the trajectories off the lake...but the overall
consensus is for a 280 to 290 deg flow...which will keep the snow
confined to areas to the north.

The flow backs to the W/SW late Saturday and Sunday but the cold air
mass persists. So, will likely see the lake band shift to the north
out of our forecast area, with temperatures continuing to be rather
cold...highs in the 20s and lows in the teens.

&&

Aviation /20z Monday through Saturday/...
precipitation moves in south to north this afternoon into this
evening but is just a little slower doing so. Once the precip
moves in by the late afternoon / early evening as rain and sleet
at first, expect mainly MVFR cigs/visbys initially. However,
through the evening snow and sleet will begin to mix in so expect
IFR visbys and cigs as well. Precip types remain a big challenge
and there is still some potential for a heavy period of all snow
this evening into the overnight over central New York sites (especially
for kith) which could bring visbys to a half mile. Precip should
become mostly snow by late tonight into tomorrow morning for all
sites except kavp/krme with IFR persisting.

Expect east winds to increase this afternoon into this evening and
be generally around 15 knots gusting 20-30 knots. These winds ease
tomorrow.



Outlook...

Tuesday...restrictions expected in rain or a wintry mix.

Wednesday...more restrictions possible in rain or snow showers.

Thursday - Saturday...restrictions possible in snow showers.

&&

Bgm watches/warnings/advisories...
PA...Winter Storm Warning until 1 PM EST Tuesday for paz038>040-043.
Winter Weather Advisory until 1 PM EST Tuesday for paz044-047-
048-072.
New York...Winter Storm Warning until 1 PM EST Tuesday for nyz009-015>018-
022>025-036-037-044>046-055>057.
Winter Weather Advisory until 1 PM EST Tuesday for nyz062.

&&

$$

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