Scientific Forecaster Discussion
fxus61 kbgm 201646
Area forecast discussion
National Weather Service Binghamton New York
1146 am EST Mon Nov 20 2017
accumulating lake effect snow will continue in north central
New York this morning, shifting mainly north of the New York
thruway by mid morning. However, at least scattered snow
showers and flurries can be expected across the rest of central
New York today and even northeast Pennsylvania this morning.
Milder temperatures and dry weather are expected into Tuesday.
Near term /through tonight/...
updated at 1130 am...
heaviest lake effect snow band east of Lake Ontario has shifted
north of Oneida County late this morning, however scattered
areas of light snow and flurries continue across central New York. The
combination of some moisture east of Lake Erie and a developing
warm front will result in scattered light snow and flurries
across much of central New York this afternoon. Some of our higher
resolution models are indicating an intensification of the snow
showers from near Syracuse to the Catskills with this scenario
later this afternoon implying the potential for another inch or
two of snow, although this will be mainly over higher terrain as
temperatures at lower elevations will be rising well above
freezing. All snow showers should be east and north of the area
early this evening as a warmer air mass arrives from the
southwest cutting off the lake effect potential. Previous
discussion is below.
315 am update...
evolution and eventual end of ongoing lake effect snow will be
the main forecast issue in the near term.
Lake Huron to Lake Ontario connection became established over
the last several hours, which on radar has stretched a 20-35
dbz band of snow across Onondaga and Madison counties, reaching
in pieces to the Cooperstown area. Under the heaviest part of
the band, 1 to 2 inch-per-hour snowfall rates are likely
occurring. Visibility has been about a half mile at times at
Syracuse and Rome overnight. As the lake-to-lake connection
band became dominant, the earlier one in Oneida County
dissipated. However, upstream the boundary layer flow is already
beginning to back westerly as evidenced by the shifting band in
Western Lake Ontario. As flow continues to back across our
region, there will be a lifting of the primary lake band
northward along and then north of the New York thruway this morning,
which will get Oneida County back into the snow. All told,
an additional 2 to 5 inches of snow is expected from 4 am
through early afternoon in the lake effect snow warning area,
with locally higher amounts in far northern Onondaga-Madison
counties. The warning GOES through 1 PM, but Onondaga-Madison-
southern Oneida counties will probably be able to be dropped
well ahead of that time as the band lifts.
Lake Ontario has not produced the only action, however. Lake
Erie has also caused band extensions to reach into the twin
tiers and even the greater Wilkes-Barre/Scranton Metro and the
Poconos at times. The resulting dusting of snow, and
temperatures falling below freezing causing ice within
previously wet roadways, will mean slick spots still possible on
untreated roads. Scattered snow showers and flurries will still
occur at times this morning for northeast PA-southern tier NY,
and into the afternoon for the rest of central New York. This will be
courtesy of Lake Erie moisture as flow continues to back
westerly to west-southwest with time. That being said, warm air
advection aloft will cause compression of the cloud layer to
significantly limit snowfall rates.
Temperatures today will quietly sneak up in the mid 30s-near 40
for highs, which along with dry air and west winds gusting 15-25
mph, as well as ground temperatures still well above freezing; will
tend to melt or sublimate the fluffy lake snow. Higher terrain
of central New York however will struggle to get above the lower 30s.
Southwest to south flow, and warm air advection aloft, will lead
to a clearing sky into tonight. Temperatures will settle into
the upper 20s-lower 30s this evening, then hold fairly steady
Short term /Tuesday through Tuesday night/...
mild SW flow continues Tuesday as a low pressure system and
associated upper level trough move across northern Ontario.
Expect plenty of sunshine with highs mainly in the low 50s to
even some mid 50s across the warmer spots such as the Wyoming
Valley and western southern tier into the lake plain. The cold
front associated with this low will move across the area after
midnight Tuesday night bringing with it a swath of rain showers
which will change over to snow showers in the cooler air behind
the front. Not expecting this will amount to much
accumulation....at most a coating to half inch, if that by
Wednesday morning with any accumulation being mainly limited to
higher terrain areas of central New York. The other complicating
factor with this part of the forecast will be that some of the
models (gem and ecmwf) hook this front up with some moisture
coming up from the south which could enhance precip a bit over
eastern zones through the Catskills. This will have to be
monitored for future updates. Lows by Wednesday morning will be
generally in the low to mid 30s.
For Wednesday, some lingering precip will continue to be
possible into the morning with otherwise a mainly dry and
cooler day behind the front. The one exception will be across
northern counties where some weak lake effect snow will be
possible around the I-90 corridor in the cold northwest flow off the
lakes however this doesn't look to amount to much. Highs will
generally range from the mid 30s to low 40s, mildest over NE PA
and Sullivan County.
High pressure builds in for Wednesday night setting the stage
for a cold night under mainly clear to partly cloudy skies with
light winds. Lows will be mainly in the low to mid 20s with
some teens possible across the colder spots in Steuben County as
well as the Catskills.
The ridge of high pressure moves off to the S/east Thanksgiving day
but conditions stay mainly dry with sunshine giving way to some
increasing late day clouds ahead of the next front approaching
from the north. A developing west/SW flow could spark a Few Lake
effect flurries late day north of I-90 but this should not be of
Long term /Wednesday through Sunday/...
320 PM update...
upper low moves from the Hudson Bay into Quebec Thursday night
into Friday, bringing a cold front into the upstate. We may see
a little bit of light snow over (mainly) the northern tier of
counties Friday in association with the front. By Friday
evening, though, the boundary layer flow is expected to become
southwesterly and set up a low-level warm advection pattern over
the region as the front moves back north as a warm front.
Forecast confidence wanes from there. Plenty of discrepancies are
evident with regard to timing, evolution, and impacts from the next
system. In general, expect precipitation probabilities to increase
heading into next weekend as the upper-level storm system pushes a
surface low from Ontario into Quebec. Depending on the upper
trough's amplitude, this could push the associated cold fronts
through the region sometime between Saturday night and Sunday night.
I've stayed fairly close to the model blend during this period given
Aviation /18z Monday through Saturday/...
lake effect snow will be winding down today, but the Main Lake
Ontario snowband will still impact ksyr and krme through 14z
and 17z respectively with below alternate minimum visibility at
times. Scattered flurries will be found elsewhere, courtesy of
Lake Erie moisture drifting by the area, but with few if any
associated restrictions. VFR will become predominant across the
region, with 4-6 kft agl ceilings lifting and scattering out
with time. West-northwest winds of 9-12 knots, with gusts of 16-20 knots,
will slacken while backing southwest late afternoon through
evening. Though the sky will clear out into tonight, there will
also be an increasing southwesterly low level jet of 35-40
knots which will cause development of low level wind shear for
at least the New York terminals; it will be borderline for kavp.
Tuesday night through Wednesday...restrictions possible in
scattered rain/snow showers.
Wednesday night through Friday...mainly VFR.
New York...Lake effect snow warning until 1 PM EST this afternoon for