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000
FXUS61 KBGM 200841
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
341 AM EST Wed Feb 20 2019

.SYNOPSIS...
Another light wintry mix today and tonight will move across the
region, along with gusty south winds. Mostly quiet conditions
later in the day Thursday through Friday into early Saturday.
The next low pressure system will impact the region later
Saturday through Sunday into Monday with more wintry mix and
strong winds.

&&

.NEAR TERM /THROUGH THURSDAY/...
340 am update...
Main concerns in the near term remain focused on the incoming
wintery mix of snow, sleet and freezing rain later today and
tonight...along with strong s/se winds across the Finger Lakes
tonight and noticeably warmer temperatures on Thursday with
lingering light rain/snow showers to the north.

High pressure at the surface shifting off to the east this
morning but still having enough influence on the area to keep
weather conditions quiet. High clouds have moved in, and will
continue to see clouds thicken through the morning before snow
moves in from the s/sw around 9 to 10 am into ne PA. Atmosphere
still expected to be cold enough for all snow through most of
the afternoon with the snow shield spreading to the northeast,
and dropping 1-2 inches across central NY and 2 to 3 inches into
ne PA. This part of the forecast remains relatively unchanged.
However, there have been slight adjustments made to the total
snow and ice accumulations...especially during the evening and
early overnight hours.

Model guidance has come into slightly better agreement with
respect to the the depth and amt of warm air aloft and cold air
near the surface. At this time there appears to be a greater
potential of sleet rather than freezing rain...although light
ice amounts are still expected...so this result has caused
total snow amounts to be slightly higher than the previous
forecast, although not substantially higher. With the p-type
leaning more toward sleet, this will cut back on the ice
accretion...with most areas of central NY less than 0.05"...and
areas of ne PA 0.10" or less.

Still expecting a change over of snow to sleet from west to
east during the late afternoon and early evening time
frame...and then a couple hours later, mixing with freezing
rain. The freezing precip may end up actually being fairly
light...more likely freezing drizzle as the column loses ice
crystals aloft and the dry wedge moves in from the west.

The sfc pressure gradient tightens this evening as the surface
low to the west deepens slightly and moves east...and the high
off the coast takes its time moving out of the area. These two
features will cause sustained south/se winds around 10 to 20 mph
and gusts up to 30 mph into the Finger Lakes. Gusty winds are
possible in the higher terrain of the Catskills and the
Allegheny plateau, but the strongest winds will be from
downsloping into the Finger Lakes.

Wintry mix will taper off west to east after midnight and change
to mostly liquid (drizzle or light rain) for most of the area by
or just after sunrise Thursday morning. The air mass behind the
departing system will be fairly cold once again...and allow for
a weak lake reaction across the far nrn counties into Thursday
afternoon. Surface temperatures will warm into the upper 30s
north and into the lower 40s south. Even with temperatures above
freezing, the air mass aloft will likely be supportive of light
snow or drizzle off the lake into mainly Oneida county. Areas
south of the Thruway will likely be dry most of the day Thursday
as the dry punch and surface ridge axis pushes east.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
310 AM Update...
Fairly benign period expected in the short term with little if
any precipitation behind the front Thursday night, then a
gradual breakup of stratocumulus Friday into Friday night.

Weak cold air advection will continue Thursday night along with
west-northwest flow. The moisture that will exist will be quite
shallow; confined to a sharp inversion around or below the 800mb
level. While it appears that there will likely be stratocumulus
for most of the area, the depth of the moisture will make
precipitation hard to come by. The top of the layer reaches to
about minus 10 Celsius Thursday evening, which should prevent
drizzle/freezing drizzle by then. However, a few scant flurries
cannot be ruled out in Central NY north of Cortland-Norwich and
mostly east of Syracuse. With the clouds, temperatures will be
prevented from dropping any lower than 20s for lows.

Stratocumulus layer will thin with time of Friday, and as usual
it will linger longest in North Central New York while others
will start getting into more sunshine especially in afternoon.
High pressure will pass across the region Friday afternoon-
evening, then just east by dawn Saturday. Highs of mid 30s-lower
40s Friday, will be followed by lows of upper teens-mid 20s
Friday night thanks to a mostly clear sky allowing for
radiational cooling.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
310 AM Update...
Main concern in the long term period, is the increasing signal
for a possible wind event as a deepening low pressure system
passes through the region Sunday into Monday. Also, the same
system will bring varying types of precipitation ahead of,
during, and behind the system.

A low pressure center is projected to exit the Central Plains
Saturday, which then rapidly deepens Saturday night into Sunday
while moving through the western Great Lakes into Ontario-
Quebec. To differing degrees, yet with the same general idea,
the ECMWF Canadian and especially GFS models have this occur as
southern stream and northern stream upper waves phase with each
other while lifting northeastward. Based on local studies there
are several parameters meeting thresholds of past stronger wind
events including 925-850mb winds exceeding 50 knots, low level
lapse rates in excess of 8 deg C/km, as well as a strong
pressure rise-fall couplet in terms of 6 hour pressure change.
While zone of strongest winds and pressure rises appears to
translate from western to northern NY and especially into
Canada, areawide it appears that it will get quite gusty Sunday
through Sunday night and perhaps into Monday as well. If a
verbatim GFS solution were to pan out, damaging gusts are not
out the question especially from the Finger Lakes to Mohawk
Valley areas but perhaps further south too. Sometimes the
magnitude of a potential wind event looks high several days
out, only to diminish as it gets closer. For now though, we will
be adding mention of this potential to our local Hazardous
Weather Outlook for northern parts of our area to raise
awareness, where potential is higher, and we will otherwise
continue to monitor trends in coming days.

Besides wind, the other impacts of this system of course will
involve precipitation. Strong warm air advection will occur
especially later Saturday into Sunday. As increasing moisture
and lift occur on the front side of the system, a shield of
precipitation will lift south to north across the area later
Saturday through especially Saturday night. It is not totally
impossible that a brief wintry mix could occur, especially
higher terrain east of I-81, but overall it appears strength of
warm air advection as well as relatively limited cold air
damming in the low levels will make rain the predominant
precipitation type. Temperatures will surge into Sunday with
highs of at least upper 40s-lower 50s expected.

Blast of cold air advection and gusty winds will then occur
later Sunday through Monday. What is left of rain showers will
change back to snow showers Sunday night. Some accumulating
lake snows could occur into Monday in parts of Central New York
with gusty cyclonic flow on the back side of the system with
potential to pick up Great Lakes moisture from well upstream.
Then, brief ridging by Monday night into Tuesday appears to
yield a temporary respite of quiet weather.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
An area of snow will move in after 15Z from southwest to
northeast and eventually change to a snow/sleet mix for period
after 21Z, and then mix in some freezing rain after 02Z
Thursday. Expect IFR visibilities between 3/4SM and 2SM in
moderate snow with ceilings between 1000 and 2000 feet. Vsbys
will improve with the transition to a wintry mix...with cigs
remaining in the fuel alternate required to low-end MVFR range.

A strong s/sw low level jet around 40-50 kt will induce some
LLWS across the area after 00Z Thursday.

Outlook...

Wednesday night through Thursday...MVFR/IFR restrictions likely
as the snow and sleet transition to rain around sunrise
Thursday morning. Rain showers continue Thursday with brief
isolated restrictions possible. Light lake effect rain and
eventually snow showers at KRME may reduce vsbys and cigs as
well Thursday night.

Friday and Saturday...VFR under high pressure.

Saturday night through Sunday...Restrictions likely in mixed
precipitation.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory from 10 AM this morning to 7 AM EST
     Thursday for PAZ038>040-043-044-047-048-072.
NY...Winter Weather Advisory from 10 AM this morning to 7 AM EST
     Thursday for NYZ009-015>018-022>025-036-037-044>046-
     055>057-062.

&&

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