NWS Forecast Discussion

000
FXUS61 KBGM 190226
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
926 PM EST Mon Feb 18 2019

.SYNOPSIS...
Lake effect snow showers will continue over the Finger Lakes
and into the Southern Tier tonight. High pressure will build in
and give us drier weather Tuesday. A complex low pressure
system will bring snow and mixed precipitation once again
Wednesday into Thursday.

&&

.NEAR TERM /THROUGH TUESDAY/...
9 pm update...
Just minor changes again.
Some clearing starting to show up in the Finger Lakes and Tug
Hill. Temperatures in northern Oneida have fallen into the
single digits now. Lowered hourly and min temps some especially
northeast quarter. Lake effect has weakened but coverage only
slightly reduced. This trend will continue tonight.

6 pm update...
Lake effect continues across most of the CWA but satellite and
radar trends show a decrease in coverage and intensity.
Northwest winds are bringing in colder air despite the clouds.
Minor update to adjust to current.

previous discussion...
High pressure over the central Great lakes will keep a northerly
flow off Lake Ontario and into the Finger Lakes region. With
temperatures dropping, this will keep enough instability and
moisture for some very light lake effect snow showers and
flurries to continue for much of the night. Best chance will be
nearer the lake in the upslope areas just south of I90. Some
light flurries will be possible south of there to around the PA
border.

To the east, clear skies and northerly flow will bring dry air
and drainage winds dropping temps below zero in the extreme
north, and the single numbers over the Catskills.

On Tuesday, the high builds overhead finally cutting off the
lake effect and bringing February sunshine. Max temps will
rebound to near normal for this time of the year.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Surface high pressure will slowly exit the region Tuesday night.
Behind it, some high clouds will start to move in ahead of the
next system. This will keep temperatures from falling much lower
than around 10 for most of the area despite light winds.

Another area of low pressure looks to track from the Ohio Valley
into the eastern Great Lakes with a secondary low forming off
the Mid-Atlantic coast. A warm front will accompany these low
pressure systems that moves through Wednesday night into
Thursday. Light precipitation is likely to develop as snow
Wednesday afternoon from south to north. Thermal profiles
continue mid-level warming around 750-900 mb before the surface
with a changeover to a wintry mix by mid-evening and perhaps to
rain overnight. Right now the 12z NAM 1/18 thermal profiles were
weighed more with the precipitation type and temperature
compared to the GFS which erodes the low-level cold way too
fast. Temperatures warm enough Thursday for the precipitation to
end as rain.

The best lift with the overrunning moisture looks to stay south
of the region in the Mid-Atlantic Wednesday with lighter
precipitation across our region. Some uncertainty in the
location of the best lift along the warm front is still present
with the ECMWF having this additional precipitation get into
portions of the Poconos in the day. However, the 12z NAM looks
to be a very aggressive outlier showing several inches of snow
from the Southern Tier southward into the Poconos with this
first round of precipitation. A second period of steadier
precipitation looks to track a bit further north than compared
to previous model cycles Wednesday night with this rain or mixed
precipitation getting into the Poconos.

Overall, a fairly consistent signal within the ensembles the
past several days with QPF more in the .1-.2 range at this
time in our New York counties. QPF has trended higher in the
Poconos with the second period of steadier precipitation
trending further northward Wednesday night. The GFS 12Z 2/18
continues to show some terrain enhancement across Oneida county
Thursday morning as well.

Currently, an inch or two of snow accumulation followed by a
light icing is the most likely outcome before a change to some
scattered rain showers late Wednesday night or Thursday. Higher
snow amounts closer to 3 inches are possible in the Poconos
with more in the way of QPF. Daytime temperatures Wednesday look
to top out in the 20`s then warm some Wednesday night with a
non- diurnal trend still anticipated.

Ensemble guidance is backing off slightly with warmer
temperatures on Thursday. This is likely be due to our region
being in the warm sector during the day as rain showers clear
out. The ECMWF suite is most aggressive with this warm-up and
has had a few occasions recently where the more aggressive warm-
up option several days out has occurred. However, the NAM hangs
around low level cold and the GFS lingers some light
precipitation. Both of those outcomes would limit warming on
Thursday. This forecast will keep temperatures more in the
direction of the ECMWF with modeled 925 mb temperatures above
0C, getting afternoon highs into the 40`s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A chance for lake-effect snow showers lingers Thursday night
into Friday morning behind the exiting low pressure system,
then this winds down after sunrise Friday with shifting winds
and high pressure building over the region. Dry weather and even
some breaks in the clouds are expected the rest of the day
Friday through Saturday morning, then chances for snow and mixed
precipitation return later Saturday as a low pressure system
developing in the Lower Midwest funnels warmer and more moist
air into our region. Rain and periods of wintry mix continue
through Sunday as this system moves through the Great Lakes.
Chances for rain and mixed precipitation continue throughout the
day Monday as another upper- level wave moves through behind
this exiting system.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
630 pm update...

A northwest low level flow of colder air is keeping the lake
effect snow going over the area. At most sites conditions have
improved to VFR. ITH will have the worst conditions with MVFR
cigs/vsbys until 15z Tuesday. This evening until 04z vsbys could
fall to IFR and cigs will be MVFR fuel alternate. BGM could fall
to MVFR at times until 02z and maybe beyond. Other sites may
briefly fall to MVFR tonight.

Tuesday with high pressure building in skies will become
scattered to clear with VFR conditions.

Northwest winds will be 5 to 10 kts tonight and Tuesday.

Outlook...

Tuesday night into early Wednesday...VFR.

Wednesday night through Thursday...Restrictions likely in snow,
mixed precipitation or rain.

Friday and Saturday...VFR under high pressure.

&&

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

&&

$$
SYNOPSIS...DGM/TAC
NEAR TERM...DGM/TAC
SHORT TERM...MWG
LONG TERM...HLC
AVIATION...TAC

NWS BGM Office Area Weather Forecast Discussion