307 
FXUS61 KBGM 051604
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
1104 AM EST Sat Jan 5 2019

.SYNOPSIS...
A low pressure system moving across the Delmarva will keep rain
over our southern and eastern forecast areas today. A cold 
front will move through tonight and trigger a few light snow 
showers across the region into the day Sunday.

&&

.NEAR TERM /THROUGH SUNDAY/...

1100 AM Update...

Temperatures have risen above freezing for just about all
locations seeing precipitation, therefore the winter weather
advisory was allowed to expire on time, at 8 AM this morning.
Light rain continues along and SE of the I-88 corridor and
across most of NE PA late this morning. Coastal low continues to
spin off the DELMARVA/NJ coast, and is bringing a steadier band
of rain from near Scranton to Monticello and points east. All 
of this rain will gradually shift off to the south and east, 
eventually out of the forecast area later this afternoon. 
Additional rainfall amounts will be mainly under a tenth of an 
inch...except locally around a third of an inch in Sullivan/Pike
counties. Across our western zones subsidence is occurring, with
partly to mostly sunny skies across the Finger Lakes. Expect a
few breaks of sun to move east this afternoon, across Central
NY. Temperatures should rise into the upper 30s to mid-40s this
afternoon. Winds shift northwesterly, around 10 mph. Clouds then
quickly move back in from western NY this evening, with
scattered snow showers developing overnight as modest cold air
advection begins. Temperatures only gradually fall overnight,
dipping down into the upper 20s to mid-30s toward daybreak.

205 AM update...

Temperatures this morning are much colder than the models
indicated. With readings in the middle-20s across portions of
the Twin Tiers and Catskills, we opted to issue a short term
winter weather advisory for our central forecast area effective
until 13z. We anticipate temperatures will sufficiently rise 
over the next 2-4 hours and allow us to cancel at least a 
portion of the advisory.

The Delmarva storm system will slide northeastward today and
pull rain across our eastern forecast area, while dry air
filters into the Finger Lakes and Central Southern Tier. Rain
will exit our region during the afternoon hours.

Colder air sliding across Lake Ontario will generate lake effect
snow and rain showers tonight. Accumulations will be light.
There is some indication that ice crystal formation will once
again be an issue. While spotty freezing drizzle is possible,
temperatures are marginal for freezing precipitation. We don't
anticipate including freezing drizzle in the lake activity with
this forecast package.

Light lake effect snow shower activity will continue over the
northern half of our forecast area on Sunday. Temperatures will
reach the middle-30s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
415 AM Update... 
After quiet conditions Sunday night through midday Monday, main
concern continues to be potential for a wintry mix event late 
Monday through early Tuesday.

High pressure will pass overhead Sunday night with a period of
mostly clear sky between breakup of stratocumulus, and incoming
high thin clouds towards dawn. The resulting radiational cooling
of a cold dry air mass will send lows into mostly the teens,
though a good chunk of Central NY is likely to reach single
digits to 12 degrees, especially east of I-81 and including
Cortland-Syracuse. Brief filtered/partial sun is possible at
dawn but clouds will be quickly increasing and thickening Monday
morning.

Confidence in details of system for Monday afternoon through
early Tuesday has actually gone down, as models are presenting 
a wider range of possibilities and amounts instead of 
converging towards a single solution. What all models have in 
common, however, is a window of time in which a layer of warm 
air aloft will cause sleet or freezing rain to become a primary 
precipitation type. How long each precipitation type lasts is 
in question and will also vary by area, but the general 
progression will be as follows. The front end begins as snow- 
sleet, then freezing rain will also enter the picture with time 
Monday night as the warm layer lowers/cold near surface layer 
thins, before plain rain as surface also warms into early-mid 
Tuesday. Model consensus trend is for the better accumulating 
snow potential to be shoved further northeast than before, with 
1-3 inches probably being reserved for Oneida-eastern Otsego- 
eastern Delaware and mostly less than an inch for the remainder 
of the area; almost none south and west. Big question for how 
much of the liquid-to-freezing precipitation will be sleet 
versus freezing rain, but just about the whole area could end up
with a very light glaze. Primary problem time in that regard 
would be late Monday afternoon-early evening southwest, moving 
across areawide during Monday night, then far northeast by dawn
Tuesday. 

There will be a solid pressure gradient between high pressure 
stretching across New England into the Atlantic, and the low 
pressure in western to central Ontario. The south-southeast
flow in between could get a bit zesty Monday night especially 
higher terrain, as well as channeled drainages/downslopes of the
Finger Lakes. Models are also starting to hint at a large 
elevation dependence for total precipitation amounts, with 
potential wind shadowing causing relative minimums in the 
Central Southern Tier to Finger Lakes in NY as well as perhaps 
the Wyoming Valley in PA. Likewise, northern Oneida could get
upslope enhancement to snow/sleet, and thus somewhat higher
expectations for snow accumulations there.

Temperatures will continue to their early morning surge Tuesday,
to achieve highs of upper 30s-upper 40s during the day.
Rain/wintry mix in the east will also quickly end, yet another
wave wobbling in attached to the Canadian upper low could bring
another round of mostly rain showers through the area later Tuesday
afternoon. Cold air advection will be inbound, and thus
additional showers into Tuesday evening may start to change to
snow as detailed in the long term portion of this discussion.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Tuesday night: Another shortwave upper level trough moves into 
our area from the Great Lakes region. This trough could become a
closed mid and/or upper level low as it moves across northern 
NY. A surface lows is also expected to develop and move just 
north of our CWA. This system could bring another few tenths of 
an inch of QPF. Precipitation type would likely start out as 
rain Tuesday evening, but would then changeover to snow from NW 
to SE, as colder air filters into the area. Exact details remain
uncertain on this system, but it could bring another light 
accumulating snow to parts of the area. Low temperatures 
gradually fall into the upper 20s and lower 30s late at night.

Wednesday and Wednesday night: A slow moving upper level trough 
remains centered over the area. Much colder air will be in place, 
with 850mb temperatures around -8 to -12C...and surface temperatures 
holding in the lower to mid-30s for most locations during the day. A 
moist synoptic wrap around flow, and lake enhancement will produce 
high chance PoPs for snow showers. Overnight lows dip down into the 
lower to mid-20s.

Thursday: Colder, with still a chance for lingering lake effect snow 
showers as the upper trough only very slowly moves off the East 
Coast. Highs range from the lower to mid-20s north, to lower 30s in 
the Wyoming Valley of NE PA.

Friday: Brief upper level ridging moves in for dry weather and 
seasonable temperatures.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
A storm system moving across the Delmarva will spread rain
showers and MVFR conditions across KAVP, KBGM, KITH, and KELM 
this morning. Ceilings will mainly be between 1200 and 2500 
feet in the rain showers, with visibilities of 2SM to 5SM. 
Spotty freezing rain and light snow will be possible at KITH and
KELM through 13z.

The storm system will shift the rain and clouds eastward this
afternoon, with the region returning to VFR conditions.

Light lake effect snow showers are expected to bring occasional
MVFR visibilities and ceilings into KSYR and KRME after 03z
Sunday.

Outlook... 

Saturday night and Sunday...Mostly VFR, but possibly MVFR at 
KSYR/KRME in scattered lake effect snow showers.

Sunday night through Tuesday...Mainly VFR through Monday 
morning then lowering ceilings to MVFR and IFR with rain and/or
snow by Monday night. MVFR and IFR ceilings with more 
precipitation through Tuesday.

Tuesday night through Wednesday...Restrictions possible in snow
showers, mainly KRME/KSYR.

&&

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

&&

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