713 
FXUS61 KBGM 290901
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
401 AM EST Tue Jan 29 2019

.SYNOPSIS...
A cyclone moving through the Great Lakes will spread snow across
NY and PA through Tuesday night. A blast of Arctic air will
bring very cold temperatures and wind chills to our forecast
area Wednesday through Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
830 PM Update...
Latest incoming model trends confirm the adjustments that were 
made earlier; lowering expected snow amounts along and 
especially west of I-81 while maintaining the relatively higher
amounts to the east. It has become clear that the initial round
of snow will be on the light side; as in for the majority of the
area only about an inch or less by dawn except for more like 
2-3 inches north of the NY Thruway such as where topographical 
lift will occur in northern Oneida County. Also, some blowing
snow can be expected at higher elevations overnight as already 
detailed in the previous discussion below, before winds slacken
during the day. 

The more interesting part of the system in terms of snow amounts 
will indeed be midday Tuesday through especially afternoon-
evening as an additional wave of low pressure rides up along the
front that for a time gets hung up just east of I-81. That will
be when the higher snowfall rates of a half inch to one inch 
per hour may be attained. Biggest point of uncertainty remains 
the I-81 corridor itself in NY and into northern Tier PA. That 
is, how far west will that second batch reach courtesy of the 
additional wave of low pressure as well as better forced ascent 
behind the front, from jet support during that time. Latest 
models have the higher probabilities primarily east of Towanda- 
Binghamton-Syracuse, especially Poconos to Catskills as well as
continuing all the way up to the southern Tug Hill Plateau, for
that second batch with a pretty sharp cutoff in amounts to the 
west. There is some suggestion that a brief deformation band 
could hang for a time around Cayuga-Cortland-Onondaga for maybe 
a bonus couple late-day inches but models differ considerably.

Previous discussion... 
Winter storm warnings are in effect from 1 am tonight until 1 
am Wednesday from Oneida County down into the western Catskills,
and Wayne/Pike counties in NE PA. A winter weather advisory is 
in effect for the same time period from Onondaga county, down to
Tioga county (NY) and points east in central NY and across the 
rest of our NE PA counties not covered by the warning.

Snow looks to arrive across our western zones around midnight, 
then spread east across the rest of the area during the predawn 
hours. Adjusted snow/QPF amounts for tonight based on the latest
guidance, which showed a general decrease in amounts. Snow 
amounts will be 1 inch or less through 7am Tuesday; except 1 to 
3 inches across Oneida and far northern Onondaga counties. 
Southeast winds increase tonight, 10-20 mph, with higher gusts 
30-35 mph possible across the ridgetops of Central NY. 
Temperatures hold steady or slowly rise into the 20s overnight. 
Could see localized areas of blowing snow, especially over the 
higher terrain.

Tuesday: First round of snow moves along and east of the I-81
corridor by mid-morning, with a brief break behind this across
the central southern tier and Finger Lakes. As the front stalls
and a weak wave of low pressure begins to ride north along it, 
another area of snow will develop and overspread the area from 
south to north Tuesday afternoon. There will be local upslope 
enhancements across the southern Tug Hill Plateau and portions 
of the Catskills/Poconos on a south-southwest flow. This second 
batch of snow looks to mainly impact areas from about Towanda-- 
Elmira--Ithaca and Auburn eastward...with the steadiest/heavier 
snow east of I-81. Back to the west expect only scattered snow 
showers Tuesday afternoon. Model guidance continues to waver a 
bit on the exact location of the higher QPF/Snow amounts...but 
at this time best estimates for snow amounts during the day 
Tuesday are: less than 2 inches west of Auburn--Ithaca--Elmira--
Towanda, 2 to 5 inches along the I-81 corridor from Syracuse-- 
Binghamton and Scranton...and 4 to 8 inches across Oneida County
down into the western Catskills and Poconos. This system is 
looking colder overall than it was a few days ago, so am 
expecting all snow for ptype, but surface temperatures could 
still warm into the upper 20s to lower 30s Tuesday afternoon. 
Snow ratios look to be mostly 12-15:1 on Tuesday. There looks to
be a period between about 18z Tuesday and 03z Wednesday where 
the snow growth region is well aligned with an omega max in the 
column...therefore good flake production (dendrites) are 
expected. Snowfall rates could occasional approach 1 inch per 
hour or so in the warning areas Tuesday afternoon and 
evening...with mostly 1/2 to 3/4 of an inch per hour, moderate, 
type snow in the advisory areas. Winds decrease some on Tuesday,
mainly SSW 6-12 mph, so blowing snow is not expected to be much
of an issue. Confidence in this forecast is moderate at this 
time. If the guidance continues to trend toward a weaker/further
east wave of low pressure than lower snowfall amounts would 
occur. Conversely, if this wave of low pressure is stronger snow
amounts could still end up a bit higher.

Tuesday night: Periods of snow linger into the evening hours as
the wave of low pressure moves off to the east. Most of the
steady snow looks to end by midnight, with much colder air and
snow showers filtering in behind it. Additional snow amounts of
1 to 3 inches expected east of I-81...with less than 1 inch
west. Winds shift westerly, 6-12 mph with patchy blowing snow.
Temperatures fall to between 0 and 10 above by daybreak
Wednesday, with wind chills 0 to 10 below by morning.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
400 am update...
A very cold Arctic air mass will plow into the region Wed night 
through Friday with temperatures in the single digits above zero 
during the day, and dropping back below zero at night. A persistent 
5 to 15 mph w/sw wind during this time will produce wind chills -15 
to -30 deg F...and a steady band of lake effect snow showers east of 
Lake Ontario, which may clip portions of nrn Oneida county with more 
than 10 inches of snow over approximately 36 hours. 

Large upper level low moving east through Quebec Wed night into 
Thursday will have an embedded trailing short wave extending back 
into wrn Ontario and the wrn Great Lakes. This feature will allow 
the long wave trough to be somewhat flattened...and keep the low 
level wind flow west-southwesterly. This will keep the bulk of the 
lake effect snow e/ne of Lakes Erie and Ontario Wed night through 
Thursday night. Temperatures at 850mb will remain steady around 
-25 deg C...inducing sufficient low level lapse rates for 
accumulating lake effect snow...even if the flakes will be in the 
form of tiny ice crystals with the dendrite zone near the surface. 
May see snow amounts 8-12 inches in the far northern areas of Oneida 
county during this time. A Winter Storm Warning for lake effect snow 
may be needed after we get through the round of snow today and 
tonight. 

Overnight low temperatures Wed night will fall into the single 
digits below zero...with a few lower teens below zero possible in 
higher elevations. Winds will also be brisk out of the w/sw 10 to 20 
mph with gusts 25 mph, which will produce wind chill values 20 to 30 
below zero. There will be some improvement during the day Thursday 
with temperatures getting above zero, but with the winds remaining 
around 5 to 15 mph, wind chill values will hold in the teens below 
zero through the day. Winds relax somewhat Thursday night, but 
remain strong enough to bring wind chills back into the teens and 
20s below zero. 

Friday may be somewhat of a transition day with temperatures 
climbing back into the teens above zero and west winds only around 5 
mph. Boundary layer winds start to go more westerly or just north of 
west...which will start to shift the Lake Ontario band south...but 
still north of the Thruway. 

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
400 am update...
Upper level trough will continue shifting to the east Friday night 
into Saturday...which will allow the winds to veer more to the n/nw. 
The lake band off of Ontario will rotate to the south into the ern 
Finger Lakes, Mohawk Valley and the hills south of Syracuse. 
However, as this occurs the 850mb ridge axis will begin to slide in 
from the west, along with a surface high and a gradual warming air 
mass. So, it looks like there will be at least a short window of 
opportunity for light accumulating lake effect snow into the 
Syracuse area Fri night and Sat morning. 

The large scale synoptic flow pattern becomes quasi-zonal later in 
the day Saturday with a much more mild air mass as well. High 
temperatures on Saturday will reach into the lower to mid 20s. There 
are some differing opinions with respect to what happens on Sunday, 
but the consensus seems to bring a weak wave ewd through 
Ontario/Quebec, and brush the nrn counties with a wintry mix, and 
some light rain to the south. Thermal profiles are widely varying as 
well, but at this time it looks like temperatures will warm into the 
mid to upper 30s on Sunday...and again on Monday. A more potent low 
pressure system looks to be taking shape on Monday over the Great 
Lakes, which would most likely put NY/PA in the warm sector...with 
an additional round of wintry mix overnight and rain during the
day. 

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A cyclone moving through the Great Lakes will spread snow across
the terminals through Tuesday evening. The most persistent snows
will be along and east of the I-81 corridor. Widespread MVFR
conditions are forecast today from KSYR and KRME south to KAVP.
The best chance for IFR visibilities and ceilings will be
between 18z and 24z.

Winds will be southeasterly at 10 to 20 knots this morning, then
shift to the west and become gusty later today after a cold 
front passes.

Outlook... 

Wednesday: Scattered snow showers and some restrictions 
possible, especially NY terminals.

Thursday: Lake effect snow mainly north of SYR-RME; but periodic
restrictions still possible in snow showers.

Friday: Mainly VFR. Lingering snow showers still possible SYR- 
RME

Saturday: High pressure. Mainly VFR expected.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 1 AM EST Wednesday for PAZ038-
     039-043-044-047.
     Winter Storm Warning until 1 AM EST Wednesday for PAZ040-048-
     072.
NY...Winter Weather Advisory until 1 AM EST Wednesday for NYZ018-
     036-044-045-055-056.
     Winter Storm Warning until 1 AM EST Wednesday for NYZ009-037-
     046-057-062.

&&

$$
SYNOPSIS...DJP
NEAR TERM...MJM/MDP
SHORT TERM...BJT
LONG TERM...BJT
AVIATION...DJP