Scientific Forecaster Discussion
fxus61 kbgm 181550
Area forecast discussion
National Weather Service Binghamton New York
issued by National Weather Service State College PA
1050 am EST Mon Nov 18 2019
coastal low passes well to our east today, but an upper level
disturbance will bring the chance for mixed precipitation
tonight through Tuesday morning. High pressure returns again
mid week, followed by another low pressure system on Friday.
Near term /through tonight/...
1045 am update... based on surface temperatures within the New York state
mesonet, it appears that readings have largely climbed above freezing across
the western Catskills. The same appears to be the case for the Poconos in
nepa, with Road surface temperatures also well above freezing in this area.
Thus, even with some patchy drizzle likely to continue over the higher
terrain into the early afternoon, we feel comfortable letting the Winter
Weather Advisory expire on schedule at 11 am.
Otherwise, it will be a cloudy and chilly, but largely precipitation-free
afternoon, with highs ranging from the mid 30s-lower 40s.
Previous discussion... 345 am update...
Nor'easter will be tracking south and east of the 40/70
benchmark this morning. However, forecast model soundings
continue to indicate abundant low level moisture pushing in from
the Atlantic. The moisture layer is generally below 800 mb with
thermal profiles just below 0c and temperatures at the surface
below freezing. Ground temperatures also remain below freezing.
These conditions are conducive for pockets of freezing drizzle
to develop across the Poconos and Catskills early this morning.
However, there is some concern that the moisture layer may not
be quite deep enough and we could end up with just some low
clouds and freezing fog this morning. Going to wait and see how
things materialize over the next couple of hours and if freezing
drizzle does not develop then we will have to cancel the
advisory early. Only a glaze of ice is expected in the advisory
area, however, this would be enough to cause some travel issues
for the morning commute.
Temperatures will eventually warm above freezing later this
morning and then just a plain drizzle or light rain is
expected. However, with the coastal low tracking further east,
we have lowered precip chances through the day and kept the
higher chances east of the i81 corridor for this forecast
Short term /Tuesday through Tuesday night/...
430 am update...
main concern will be for wintry mix causing reemergence of ice
glaze potential, with some light snow accumulations possible as
well, especially higher terrain along- east of Interstate 81.
Coastal low will be long gone, but a separate northern stream
upper wave will take on a negative tilt to pivot through the
area tonight. As it does so there will be upward forcing aloft
as per continued depiction of quasigeostrophic lift/q-vector
convergence in the models. Models have also trended and
consolidated towards east of Interstate 81 as being the main
target for precipitation in whichever form; the further east one
GOES the higher the potential. Thermal profiles indicate that
within the primary band moisture will be deep enough for snow
crystals to fall through the column, then be either rain or snow
depending on near surface temperatures. Outside of the primary
band, moisture layer will be shallow; or more accurately to say,
there will be a dry midlevel layer between high altitude moisture
and low altitude moisture. Thus the lower saturated layer will
be mainly warmer than minus-8 degrees celsius, making Crystal
introduction more difficult. Very light rain/freezing rain or
drizzle/freezing drizzle could thus occur, with higher terrain
along and east of Interstate 81 being more vulnerable to a
patchy light glaze of ice on untreated surfaces where below
freezing. In time, the atmospheric column gets cold enough for
primarily snow towards dawn, yet by then there will be very
little precipitation left. A skiff of an inch or so of snow will
be possible overnight in higher terrain of Catskills-Otsego-
Delaware counties with trace to several tenths of an inch
elsewhere mainly along and east of I-81. Combination of light
snow and ice accumulations may necessitate another advisory for
portions of the area. Lows tonight will be upper 20s to mid 30s.
Tuesday itself looks rather quiet under positive vorticity
advection as upper wave departs. Shallow stratocumulus will be
pervasive for most of the area, though partial sunshine may work
its way up to at least the Poconos-Catskills in the afternoon.
Pockets of drizzle or flurries may occasionally skirt the
northern Finger Lakes to New York thruway corridor at times courtesy
of lake moisture; nothing of real consequence. Highs will range
from upper 30s to mid 40s, though some higher elevation
locations of central New York will not get out of mid 30s.
Long term /Wednesday through Sunday/...
445 am update...
temperatures bump up somewhat later this week only to be batted
back slightly below average this weekend, courtesy of a low
pressure system moving through Thursday night-Friday.
Yet another upper wave will swing through the area Tuesday
night-early Wednesday, but with limited moisture. It could
possibly pick up just enough moisture off the lakes for a few
more snow showers across our central New York zones, but with little
accumulation if any. One thing we will have to keep an eye on,
is whether the cloud layer will be cold enough for snow
crystals; patchy drizzle/freezing drizzle cannot be totally
ruled out at times where lake moisture allows very light
precipitation. Lows Tuesday night will be upper 20s-lower 30s
followed by highs of mid 30s-mid 40s Wednesday.
High pressure will pass through the region Wednesday night
through midday Thursday with quiet dry weather.
Models continue to be in fair agreement on a new low ejecting
out of the Central Plains Thursday, zipping across the central
Great Lakes Thursday night into southern Ontario-Quebec Friday.
This will be in response to a new upper trough digging into the
Great Lakes to northeast during that time. Warm air advection
ahead of the system will send temperatures well into the 40s
for most locations Thursday, while maintaining above freezing
Thursday night-Friday morning. Cold frontal passage will then
cause temperatures to fall from 40s Friday to below freezing
Friday night, and then lower 30s to lower 40s for highs over the
weekend. This will support mainly rain with the system itself,
followed by lingering lake-supported moisture changing to snow
showers late Friday-Friday night. Saturday appears mainly dry
for now, but there is uncertainty as to whether weak
disturbances the remainder of the weekend could some snow or
mixed rain-snow showers at times.
Aviation /16z Monday through Friday/...
MVFR ceilings expected today as low level moisture continues to
push inland off the Atlantic. An upper level disturbance crosses
the region tonight and brings more MVFR to possible IFR
Tuesday and Wednesday...possible restrictions, mainly in New York from
light snow and rain showers.
Wednesday night into Thursday morning...likely VFR.
Thursday afternoon through Friday...restrictions possible in
periods of rain, changing to snow.
PA...Winter Weather Advisory until 11 am EST this morning for
New York...Winter Weather Advisory until 11 am EST this morning for