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fxus61 kbgm 111753 

Area forecast discussion
National Weather Service Binghamton New York
1253 PM EST Mon Nov 11 2019

spotty light rain mixed with wet snow at higher elevations will
occur this morning mainly in parts of central New York. A
strengthening low pressure system this afternoon through tonight
will cause rain or wintry mix, changing to snow. This may lead
to a messy commute Tuesday morning. Snow will be heavy at times
in the northern Finger Lakes east from Syracuse to Utica. Near
record cold is expected midweek with lake effect snow showers.


Near term /through Tuesday/...
1230 PM update...

The main adjustments with this update have been to account for
the onset of snow across our far northwest zones, and to continue to
attempt to capture the spatial extent of mixed precipitation
this evening. Snow showers/light snow are starting across our
far western zones, around Syracuse and down through the western
Finger Lakes. Snow continues across those areas through the
early afternoon, not budging much as deepening low, currently
over OH, pivots into PA and finally through New York and into New
England, dragging the cold front in through early Tuesday.

Heading into the evening, a narrow band of mixed precipitation
of freezing rain, snow, and sleet develops mainly south and
east of a line from around Utica to Union Springs to Hornell as
model soundings continue to indicate a dry pocket of air aloft
ahead of the front as it moves through central New York. Meanwhile,
across the Catskills, Poconos, and far NE PA, precipitation
should stay as mainly rain overnight, finally beginning to
transition to a mix mainly of rain/snow/sleet (though freezing
rain cannot be ruled out). Soundings are somewhat different
across those areas, staying fairly saturated ahead of the front,
with a brief window indicating a melting layer aloft before a
quick transition to snow.

Ultimately, still looking at our highest snow totals across our
northwest zones to peak in the 6-10 inch range, with up to 3 to 6
inches across our central New York zones tapering off to less than an
inch heading into far NE PA and the Catskills/Poconos.

Previous discussion continues below.

645 am update...
widely varying conditions will occur with the storm system now
inbound, but the whole area will be impacted to at least some
degree. Very light snow has already begun north of the front in
the hours just leading up to dawn, but for this morning
precipitation will continue to be light. Adjoining the Winter
Storm Warning already in effect across the northern zones, a
Winter Weather Advisory was added overnight, down to the twin
tiers. Further south, snow amounts will be lighter and freezing
rain potential less, yet even so temperatures will rapidly fall
late tonight into early Tuesday morning to cause potential
freezing up of any wet untreated roads.

Compared to prior forecast, adjustments included a further
tightening of the gradient/very slight northwestward nudge to
the heaviest snow amounts as well as higher potential for at
least a light glaze of freezing rain for much of the area even
as far north as Penn Yan-Syracuse-Utica. Overall flavor of the
storm is little changed, and models are in pretty good
agreement. Cause of the above adjustments is mainly due to
models depicting a dry slot aloft shoving northward past the
surface front, ahead of the low. With resultant loss of deeper
moisture for a brief time late today through this evening, there
will be questionable ability to introduce ice crystals from
above and also soundings show the appearance of a narrow warm
layer above the subfreezing surface layer north of the front.
Thus for The Finger lakes to New York thruway corridor, a quick window
of freezing rain and sleet can be anticipated this evening.

The deepening low itself will whip through Pennsylvania this
evening, to the Hudson Valley late tonight, on its way to
coastal New England Tuesday morning. This will cause
frontogenesis along the temperature gradient late this evening,
which will press southeast across the whole area overnight into
early Tuesday morning. Up through early evening the rain-to-
mix-to-snow line will not move very much from roughly finger
Bath to Ithaca to Cortland to Utica, but after the low passage
it will press southeast across the remainder of the area
overnight. Thus north of that line is where heaviest snow
amounts will be 4-9 inches, due to longest duration of snow.
Some spots of northern Oneida County could get around 10 inches.
To the south of that line, significantly less of total snow
will occur yet the 1-4 inches that falls will do so rather
quickly in the frontogenetical forcing band overnight-early
Tuesday morning. Model soundings for that short period show a
very thick layer in and near the dendritic growth layer as the
band moves through, and thus this thermal profile suggests
higher snowfall rates - perhaps an inch per hour or so - even
if does not last very long. This added to any brief glaze during
the rain-to-snow transition, followed by freezing up of
untreated wet roads as temperatures plummet early Tuesday, could
indeed cause headaches for the Tuesday morning commute.

On Tuesday, as the system pulls out of the area quickly in the
morning, the cold Canadian air mass will blast into the area and
allow multiband lake effect snow showers/flurries to continue
southeast of Lake Ontario most of the day. The boundary layer
will likely deepen through the day with plenty of mixing,
causing the snow showers will likely be more cellular in
nature. Could see an additional inch or two in some locations
Tuesday, but with More Lake effect coming Tuesday night-
Wednesday. Temperatures will be very cold with Tuesday dawn
readings in the 20s to near 30 and moving little during the day.
Winds will pick up out of the northwest through the
day, sustained around 15 to 20 mph and gusts up to 30 mph
possible. Expect wind chills in the single digits and teens
above zero during the day Tuesday with lower values coming.


Short term /Tuesday night through Wednesday/...
a mid-level trough of low pressure will move through the region
Tuesday nigh. With continued northwest flow into the region lake
effect snow off of Lake Ontario will become more of a concern.
There may also be a connection from Georgian Bay as well
leading to the formation of a very long but narrow snow band.
Right now preference is given to the NAM model solution as we
are still out of range for the usually preferred hi-res NAM and
rgem. While temperatures will fall quite a bit snow growth is
only semi- favorable along with lift in the Omega but enough for
ratios close to 20:1. A high amount of shear looks to be
present which local research shows lake effect snow more of a
cellular structure or moving snow band. Taking that into
account, a moving band is currently anticipated with total quantitative precipitation forecast
maxing out near and a bit northwest of Cortland around a tenth
of an inch with lower amounts to the north and south. This
translates to an inch or two of snow for a portion of central New York
south of Syracuse and north of Cortland.

Lows outside of the snow band have a good shot to fall into the
single digits with teens elsewhere. High pressure slowly builds
into the region which will cut off the lake effect. However,
with the Arctic air in place highs will struggle into the 20's.
These temperatures will be near or hit record values.


Long term /Wednesday night through Sunday/...
Wednesday night through Thursday night:

Some scattered clouds should keep temperatures in the teens or
around 10 Wednesday night even in locations with cloud cover
which prevents a tanking of the temperatures. A weak clipper
type system will pass through the region or off to our north on
Thursday. This has trended a little farther north and continues
to look rather week. Enough lift looks to be present with this
system for a few snow showers or flurries on Thursday. With a
return to southerly flow on the backside of the high highs
should get back up in the 30's and stay up in the 20's Thursday

Friday through sunday:

Modeling continues to key on another Arctic front coming
through late Friday. The cold shot behind the front looks like a
fairly quick mover though. However, it will likely mean blended
model guidance will be too cool on Friday with the southerly
flow and to warm again on Saturday. Highs should nudge into the
40's Friday but then fall back into the 30's on Saturday.
Enough lift along the front Friday should be present for some
snow showers as well, possibility mixed with rain. Temperatures
begin a warming trend Sunday with quieter weather.


Aviation /18z Monday through Saturday/...
current conditions are spread between IFR and VFR across the
region, and will become fuel alternate or worse later this
afternoon and especially this evening as the heavier snow
develops across the north.

Ksyr and krme will be situated within the heavier snow bands
after 04z with conditions at or below alternate minimums through
most of the overnight hours. Conditions improve to the north
after 10-11z...with an area of brief heavy snow sweeping east
through kith, kelm and kbgm between 06-10z. Southern New York
terminals may see IFR or below alt minimum conditions during
this time.

There is a chance of sleet and freezing rain this evening
before the push of snow and colder air from the NW early Tue
morning. Confidence is slightly less than before, so
transitioned to tempo grps for -fzra and/or pl between 23-04z.

Kavp meanwhile stays south of the frontal boundary and
associated precipitation/restrictions today. However, for a
window of time this evening marginal low level wind shear will
occur due to a southwesterly jet of 35 knots just ahead of the
front. Rain to wintry mix is then expected towards dawn with
development of fuel alternate to IFR conditions.

Winds in general with be northeast to north 5 knots or less
through this evening, though variable for kavp, then veering
north-northwest increasing to 5-10 knots late tonight...and
gusting to 15-20 kt after 14z Tue morning.


Tuesday afternoon...gusty northwest winds with scattered snow showers
and very isolated restrictions. Otherwise improving conditions
through the day.

Tuesday night through Wednesday...northwest winds and scattered
lake effect snow showers/intermittent restrictions; especially
ksyr but occasionally kbgm-kith-krme.

Wednesday night through Saturday...mainly VFR.


Bgm watches/warnings/advisories...
PA...Winter Weather Advisory from 6 PM this evening to 9 am EST
Tuesday for paz038-039.
New York...Winter Weather Advisory from 6 PM this evening to 9 am EST
Tuesday for nyz024-045-046-055-056.
Winter Storm Warning until 9 am EST Tuesday for nyz009-015>018-
Winter Weather Advisory until 9 am EST Tuesday for nyz022-023-



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