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000
FXUS61 KBGM 202056
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
456 PM EDT Wed Mar 20 2019

.SYNOPSIS...
A storm developing over the western Great Lakes will bring a
chilly rain Thursday, though it may begin as snow at higher
elevations especially east of Interstate 81. The storm will
then merge with a coastal storm, keeping things unsettled
through Friday night. Several inches of snow are possible
especially Friday night over the higher terrain of central New
York.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
3 pm update...

A mild southwest flow and sunshine has pushed temperatures well
into the 40s and lower 50s this afternoon. Warm temperatures
will continue tonight with lows in the 30s. High clouds on
their way in now across PA. Clouds will thicken and lower
tonight so that by sunrise it will be cloudy with rain moving
into NEPA and Sullivan County NY. Across the higher terrain the
rain could mix with snow. As temperatures warm into the 40s
precipitation goes to all rain for most of the day into the
evening. Maybe the highest peaks of the western Catskills get an
inch or two. The bigger issue will be the rain in NEPA and the
Catskills which will be around an inch Friday to Friday evening.
This will prime the streams and cause them to rise. Over this
length of time flooding not expected.

All of this precipitation is caused by a digging trough into the
western Great Lakes. A surface low is ahead of this but a
coastal low lifts north from the Carolinas and strengthens. Both
lows combine over NJ Thursday night and continues northeast.
These systems move slowly all the while pulling moisture
northwest into our area.

Late Thursday night as the stacked low is to our southeast
colder air comes back in changing the rain to snow. Snowfall
amounts over the higher terrain of up to 4 inches across the
higher terrain of the Catskills, Upper Susquehanna Region and
Tug Hill. With less precip to the far west and south snow
amounts over the terrain less than an inch. This could end up
being a winter weather advisory. Models coming into better
agreement but still varied. A few degrees colder or warmer will
make a huge difference. Lows again in mostly the low and mid
30s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
400 PM Update...

A complex late winter storm could impact Central NY and parts
of NE PA this period. Several pieces of upper level energy
combine to develop a strong coastal low by early Friday morning.
The ECMWF/CMC continues to indicate a stronger, more well
developed system compared to the NAM and GFS. This does appear
to be a favorable pattern for potentially significant snowfall
for at least portions of of our CWA. CIPS analog for pattern
recognition indicates that the mean snowfall from the top analog
events was around 6-10" north and northeast of Binghamton;
especially the higher elevations. The details remain uncertain
with this complex weather system, especially the thermal
profiles. A few degrees colder or warmer will make a large
difference in the ultimate snowfall amounts. Went ahead and
issued a winter storm watch from southern Cayuga east to
Cortland, Chenango, Otsego and points north. This is the area
with the highest confidence at this time for significant
snowfall.

Friday: Developing surface low pressure will be near Long Island
daybreak Friday. A deformation band of mixed rain and wet snow will
be lingering over our eastern counties in the morning. With a subtle
dry slot working into the west central portions of the area. By late
afternoon a strong upper level low slides overhead, to near NYC, and
completes the phasing of the low and mid level circulation. The
surface low deepens to around 985mb over southern New England by
around sunset. Strong cold air advection arrives by late afternoon
as the winds shift and increase out of the northwest. Another
deformation zone and wrap around snow develops on a 320 flow, with
some lake enhancement downwind of Lake Ontario. Temperatures hold
steady or even fall slightly late in the day...in the 30s...except
lower 40s for the valleys of NE PA.

Friday night: Persistent wrap around snow and snow showers continue
downwind of Lake Ontario as the 700mb and 500 mb low closes off over
southern New England. The steadiest snow will remain along and north
of the NY/PA border, with just scattered snow showers across most of
NE PA. 850mb temperatures around -11C will be marginal for
additional lake enhancement. Northwest winds increase between 15-
25 mph with gusts 30-40 mph, especially over the higher
terrain. This will lead to areas of blowing and drifting
snow...again mainly across our Central NY counties. The highest
snow accumulations are expected across the hills north of
Binghamton and south of Syracuse...extending into portions of
the Catskills, where an upslope component could add to the
snowfall. Lows drop into the upper 10s and lower 20s.

Saturday: Lingering snow showers in the morning across Central NY,
then much drier air and high pressure approach by afternoon.
Expect decreasing clouds through the day. Still remaining cold
and breezy, with highs in the 30s for central NY, with mid-30s
to lower 40s for NE PA. Winds could gusts as high as 40 mph
through early afternoon.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

After a quiet Saturday night and Sunday under weak surface
ridging, another push of unseasonably cold air will make a run
at NY and PA Sunday night, setting off snow showers. A weak wave
moving along the base of the cold air regime will strengthen
into a coastal cyclone on Monday.

Temperatures on Monday will be in the 30s across much of Upstate
NY, borderline for snow or rain. Warmer temperatures will
extend from the Twin Tiers southward.

Dry air will move into our forecast area for Tuesday and
Wednesday, though a few stray snow showers will remain possible
over our southeastern counties.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
130 pm update...

VFR conditions will persist into this evening. High clouds come
in this evening then a 5k ft ceiling around 06z. MVFR cigs come
in from south to north starting at 9z at AVP, to around 12z in
CNY. Light rain will start about that same time. Between 12 and
15z cigs fall to MVFR fuel alternate in south central NY and
AVP. AVP fall to IFR vsbys/cigs around 14z in rain.

Southwest winds at 10 kts with a few higher gusts this
afternoon. Tonight south winds at 4 to 8 kts but southeast at
SYR/RME/AVP. Thursday southeast to south winds increase to 8 to
10 kts.

Outlook...

Thursday afternoon...Restrictions likely in rain showers as a
system arrives. It may briefly start as rain-snow mix at KRME.

Thursday night through Friday...Occasional restrictions in mixed
rain-snow showers as a system continues to impact area.

Friday night through Saturday...Intermittent restrictions from
snow showers, especially the NY terminals. Gusty northwest wind.

Saturday night through Sunday...Mainly VFR.

Monday...Possible restrictions in snow and rain.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...Winter Storm Watch from Friday morning through Saturday
     morning for NYZ009-017-018-036-037-044>046.

&&

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