000 
FXUS61 KBGM 041738
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
1238 PM EST Mon Mar 4 2019

.SYNOPSIS...
Cold air behind a departing storm will generate lake effect snow
showers today and tonight. Arctic air will move into NY and PA
on Tuesday and potentially cause snow squalls to form across 
the region.

&&

.NEAR TERM /THROUGH TUESDAY/...
1055 AM UPDATE...Westerly flow developing which will end the
Finger Lake enhanced lake effect over central NY into the
northern tier of PA. Have updated the grids to reflect the trend
and adjust the temps. No major changes at this update. 


620 AM update...

Scattered snow showers will continue this morning in cold 
northwest flow behind a departing Atlantic cyclone. As snow 
showers taper off across much of the region by late morning, 
lake effect snow showers will form downwind of Lake Ontario 
today and tonight. 

Light snow accumulations are forecast. Temperatures will reach
the 20s today and fall into the single digits tonight.

An Arctic front will blast through the region on Tuesday. Model
soundings depict a high degree of instability in place across NY
and portions of PA. Squalls are likely to form along the front
on Tuesday with brief, heavy snow, low visibilities, and gusty
winds. Stay up to date with our latest forecasts on this
potential snow squall event by visiting our website at:
weather.gov/bgm

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
345 AM Update... 
The midweek period will feature very cold Arctic air, and 
fluctuating lake effect snow for counties along the New York 
Thruway, with at least scattered snow showers and flurries 
generally within the Twin Tiers and especially northward.

850mb temperatures dive to about minus-20 Celsius for Tuesday
night through Wednesday evening, before starting to moderate
slightly into Thursday. Thus the dendritic growth layer will
reside in the lowest 5 kft agl, with just about any cloud cover
producing airy dry snowflakes. Also, in addition to the
instability already offered by the very cold air mass aloft with
1000-500mb thicknesses falling to about only 500 decameters, the
ever-increasing sun angle of March will also produce diurnal
instability Wednesday and Thursday afternoons, to eke out
additional snow showers and flurries. The airmass will indeed be
very dry, limiting coverage and accumulations of snow in a
general sense. However, the primary lake feed off of Lake
Ontario will be capable of yielding several inches of snow
across portions of Onondaga-Madison-Oneida counties. One trend
in the models, though, is that there will be several embedded
shortwaves within the main upper trough that pivots through and
then gradually lifts out during the period. So while confidence
in lake effect-supporting environment remains high, the
positioning of the lake band or bands will fluctuate
considerably. 

Confidence getting greater than 7 inches in any 12 hour period 
is not high enough for any of our counties yet for a Watch or a 
Warning, but that cannot be ruled out. As it stands now, Winter
Weather Advisories easily appear likely be needed for at least 
Onondaga-Madison counties, if not some of Oneida as well at 
some point. In particular, late Tuesday night to midday 
Wednesday may include a Huron-to-Ontario connection which would 
produce higher snowfall rates. Unsure at this time how far south
this banding gets; some portions of Seneca-Cayuga could get 
involved at times as well. Look for these details to be better
ascertained over the course of the next day or so. When adding
up all of Tuesday night through Thursday, 5 to 10 inches total
will probably be realized in some of the above-mentioned 
counties, and if the primary Lake Ontario band manages to 
persist over a localized area, there could be more.

Lows Tuesday night and Wednesday night will be mainly single
digits above zero, yet with wind chills often below zero. Highs
Wednesday will be roughly 20 degrees below climatology by only
reaching mid teens to near 20. Temperatures Thursday will bump
just slightly higher by about 4-6 degrees.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
345 AM update...
Small adjustments made based on model trends. The Canadian GEM
model has joined the ECMWF at keeping Friday dry under high
pressure, whereas the GFS still skims the area with the north
side of a low pressure system. At this point we are maintaining
only slight to low chances of light snow, with the somewhat
higher chances mainly to the south. Confidence has increased
that late Friday night through Saturday evening will be dry,
with temperatures starting to moderate as discussed below.

Previous discussion...
Lake-effect snow showers linger Thursday night, then weak 
ridging may help to bring a brief dry period to most of the area
into Friday morning. There continues to be quite a bit of 
uncertainty the rest of Friday due to model differences. The GFS
continues to drag a surface low through the Ohio River Valley 
and towards the Mid Atlantic Friday afternoon, while the ECMWF, 
keeps high pressure in control the rest of Friday. Given the 
uncertainty, slight chances for snow showers will continue 
through the area the rest of the day Friday. 

Another low pressure system starts to move towards the Lower 
Great Lakes into Sunday morning, which will bring in better 
chances for snow from SW to NE across our area. This changes 
over to a rain/snow mix across most of our western zones into 
the afternoon hours. As for temperatures, expect a warming trend
Friday into the weekend. Friday morning starts off in the teens
and single digits, then we'll see highs in the 20s and low 30s.
Temperatures Saturday and Sunday should fall into the teens and
20s, but should peak generally in the 30s and even near 40F 
Sunday.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...

Developing westerly flow is lifting the lake effect snow showers
north into SYR and eventually to RME. This will bring some MVFR
restrictions to those sites, while VFR returns to ITH and BGM.
Lake effect will then lift further north bringing all stations
to VFR overnight and continuing through the end of the TAF
period. 

Outlook...

Wednesday and Thursday...Occasional restrictions possible for 
primarily the NY terminals from lake effect snow. Mostly VFR at 
AVP.

Friday and Saturday...VFR. 

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.

&&

$$
SYNOPSIS...DGM/DJP
NEAR TERM...DGM/DJP
SHORT TERM...MDP
LONG TERM...HLC/MDP
AVIATION...DGM