816 
FXUS61 KBGM 011004
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
504 AM EST Sun Dec 1 2019

.SYNOPSIS...
High pressure will keep conditions quiet tonight, but it will 
remain cold. A major storm system will hit the area Sunday and 
Monday bringing significant snow accumulation along with some 
ice. Then remaining cold with scattered snow showers and lake 
effect snow mid to late week.

&&

.NEAR TERM /THROUGH MONDAY Night/...
...Major Winter Storm to Impact the Region Beginning this 
Morning and Continuing through Monday...

Early morning update... 

A westward shift in the axis of heaviest snowfall was noted in last 
night's model guidance, putting areas west of I-81 in CNY also in 
the potential bullseye for 12"+ totals over the course of the next 
two days. Following these trends, knocked down snowfall totals 
slightly (by 1-3") across our far eastern zones (western Catskills). 
Similar changes to the snowfall forecast were made across our far 
southern zones (NEPA) with increasing confidence that sleet and 
freezing rain (especially today and most of tonight) will cut down 
on event totals. 

No changes to the winter headlines were made with this update though 
there is concern that we eventually may need to upgrade to a Winter 
Storm Warning for Steuben County and downgrade to a Winter Weather 
Advisory for portions of the Wyoming Valley if the aforementioned 
trends continue. 

Forecast Details...

Today...
At 4 AM, the leading edge of the precipitation shield was 
located to our SW across C PA and far SW NY. Observations thus 
far depict mainly sleet and freezing rain falling with this 
initial overrunning band. As precipitation overspreads the area 
from SW to NE this morning, it will eventually outrun the warm 
nose aloft, resulting in mainly snow N/E of Binghamton. A quick 
burst of snow could produce 1- 2" accumulations. Farther S/W 
(toward Steuben and across NEPA), a mix of snow/sleet/freezing 
rain will cut down on totals with this initial round. 
Nonetheless, with temperatures in the 20s, untreated roads will 
be slippery, impacting travel this morning. 

The warm nose advances northward through the day, but probably never 
makes it to north-central NY. Meanwhile, the northern progression of 
this initial overrunning snowband slows down this afternoon as the 
primary inland low begins to transfer its energy to the secondary 
low over SE VA. Accordingly, a longer period of accumulating snow 
across our far northern and eastern zones (I-90 corridor and western 
Catskills), could result in 3-6" of snow through this afternoon. 
Farther S/W, model soundings indicate a potential loss of ice 
crystals and the system's dry slot moves overhead. Decreasing PoPs 
and a trend toward light freezing rain/freezing drizzle is forecast 
for the Southern Tier of NY and NEPA this afternoon and early 
evening.

Tonight...
The primary low over the OH Valley continues to fill while the 
secondary low organizes near the NJ coast. Favorable forcing for
ascent will overspread the area late this evening and 
especially overnight as the upper low approaches from the OH 
Valley and a strengthening SEly low-level jet draws moisture 
from the Atlantic. Dynamical cooling will erode residual warm 
layer aloft, leading to a transition to steady snow from west to
east. Although there is still considerably uncertainty, this 
initial mesoscale snow band is favored to develop over CNY 
overnight and expand S/E toward early morning. Travel conditions
will quickly deteriorate under this heavy snowfall band with 
rates of 1-2" per hour expected.

Monday...
The coastal low is slow to pull away from the NJ and southern 
New England coasts. Mesoscale banding within the deformation 
zones on the northwest side of the low will allow moderate to 
heavy snow to continue into the morning across most of the area.
The snow gradually shifts to the N/E during the afternoon. It's
important to note the uncertainty regarding exactly where this 
heavy snowband sets up and how transitory it is - this has 
significant implications on snowfall amounts.

Monday night...
The snow gradually tapers off from west to east during the 
evening. An additional inch or two of accumulation is possible 
in our far eastern zones (Otsego and Delaware Counties). 

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/... 
400 AM UPDATE...

A few lingering snow showers are possible behind the big snow
storm on Tuesday over the Catskills, but the should end quickly
as weak high pressure noses in. Remainder of time Tuesday, and
into Wednesday will be dry. Later Wednesday, a short wave 
moving through the Great Lakes will push into the area bringing 
scattered snow showers. With surface temperatures rising into 
the 30s, little accumulation is expected. 

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
400 AM UPDATE...

Northwest flow behind the shortwave will bring colder air and 
and lake effect snow showers through Thursday. This activity 
will end quickly however as surface ridging arrives early 
Friday. This will be short lived as well as a stronger short 
wave and cold front arrives late Friday with even colder air. 
This will trigger yet another lake effect snow shower event that
will linger into Saturday. 

Temperatures through the period will average near normal,
although will trend lower as the coldest air arrives at the end
of the period.

&&

.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
VFR conditions will hold through the overnight hours.On Sunday,
a major storm system will push snow, sleet and freezing rain
into the region resulting in a variety of weather at the TAF
sites and rapidly deteriorating conditions. Expect a quick drop
into IFR and eventually LIFR as the precipitation moves in. 
There is also the risk of LLWS, especially at AVP as the storm 
winds up. Expect little change then through the end of the TAF 
period. 

Outlook...

Sunday night through Monday...Restrictions possible with a
wintry mix, changing over to snow for Monday and Monday night.

Tuesday...Mainly VFR.

Wednesday...Another system moving in brings chances for rain 
and snow showers with restrictions possible.

Thursday...Restrictions possible in lake effect snow showers.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Storm Warning until midnight EST Monday night for 
     PAZ038>040-043-044-047-048-072.
NY...Winter Storm Warning until midnight EST Monday night for 
     NYZ009-015>018-023>025-036-037-044>046-055>057-062.
     Winter Weather Advisory until 7 PM EST Monday for NYZ022.

&&

$$
SYNOPSIS...MJM
NEAR TERM...JRK
SHORT TERM...DGM
LONG TERM...DGM
AVIATION...DGM/DJP