Scientific Forecaster Discussion
fxus61 kbgm 201149
Area forecast discussion
National Weather Service Binghamton New York
649 am EST Wed Nov 20 2019
patchy flurries, sprinkles, or drizzle may occur southeast of
Lake Ontario and The Finger lakes today through tonight, during
otherwise quiet and cool weather. Temperatures trend milder
Thursday, ahead of a low pressure system that will bring rain
showers Thursday night into Friday. The weather turns cooler
again over the weekend with chances of rain or snow.
Near term /through Thursday/...
645 am update...
fairly quiet weather is expected in the near term, though a
very Minor Lake response southeast of Lake Ontario could produce
sprinkles-flurries and perhaps patchy drizzle later today
Things are rather quiet currently. The very light radar echoes
in the southeastern zones overnight have been virga, with too
much dry air in the 5 to 15 kft agl layer for anything to reach
the ground. That said, there is plenty of stratocumulus under
that dry layer, especially west of Catskills-Poconos. This is
helping temperatures hold up a touch milder than had been
As northwest low level flow is starting to increase this
morning, More Lake moisture is getting involved yet with 850mb
temperatures barely cool enough to generate a precipitation
response. Spotty flurries or sprinkles can thus be expected
southeast of Lake Ontario and The Finger lakes today through
tonight. Indeed radar in the last hour, and observations at
Cortland, have indicated a small blob of very light
precipitation which is now reaching into far northern Tioga-
Broome counties. With that saturated layer still being fairly
shallow, we may have a tough time generating ice crystals within
it. Thus we will have to be mindful of patchy drizzle-freezing
drizzle potential for the few spots that actually get below
freezing. Overall potential for any impact though remains quite
low, given warm ground temperatures. It may turn out to be only
very patchy thin ice of elevated surfaces such as car tops.
Highs today will be mid 30s to around 40. Lows tonight will
range from upper 20s to lower 30s; generally speaking the areas
that get below 30 degrees will not be involved with the light
spotty lake-induced precipitation. High pressure will build in
through the night, with the center of the surface high passing
to our south but extending a ridge over US.
The ridge will shove to the coast Thursday, meanwhile low
pressure will be in the western Great Lakes. Between the two,
winds will be shifting to a more southerly direction especially
Thursday afternoon, with warm air advection. Most locations will
get into the 40s; lower elevations of northeast PA to Finger
Lakes New York could even see some upper 40s. Clouds may diminish
initially, only to thicken again in the afternoon as more
moisture streams in ahead of the next system.
Short term /Thursday night through Saturday/...
models appear to be in good agreement with low pressure tracking
through the western Great Lakes into Quebec on Thursday night with a
trailing cold front sweeping across cny/nepa on Friday. Mild air
surges into the area at all levels ahead of the front, and we expect
mainly rain to occur during the first part of this weather event.
Early cooling during the evening Thursday could allow precipitation
to start as a rain/snow mix across Oneida County and the higher
terrain of the western Catskills before temperatures rise
above freezing overnight.
Showers become more numerous along the cold front, mainly Friday
morning across the north central New York counties with generally
scattered/passing shower activity further south into PA.
Temperatures drop fairly quickly behind the front during the
afternoon, and any lingering precipitation is likely to change over
to snow showers and flurries across cny and the northern tier of PA,
while rain showers and sprinkles will generally rule along and south
Temperatures swing from the 40s to lower 50s on Friday morning to
lows in the 20s by Saturday morning.
Saturday looks to be the day between weather systems with diffuse
high pressure spread over the region. Highs Saturday try to climb
back toward normal, but will probably fall just short in the upper
30s to low 40s.
Long term /Saturday night through Tuesday/...
medium range models continue to diverge in handling a high amplitude
trof, and associated low pressure development, moving into the
eastern third of the nation Saturday night and Sunday. Ensemble
spaghetti plots show a great deal of variance, but tonight's 00z
operational European model (ecmwf) and GFS models were agreeing on a more northerly
development of an East Coast low and a big jump in precipitation
chances for our area. Canadian nhemi model is still a miss as is the
mean of the gefs surface pressure and moisture fields. Confidence
remains low, but it's hard to ignore the latest model trends. My
experience tells ME to lean with westward/northward trending and
also tells ME to not jump into the deep end just yet. Nbm blended
guidance still appears to dry in this situation, so have nudged up
pops across the region on Saturday night and Sunday.
Beyond these early periods...quasi-zonal flow brings weak
disturbances and glancing effects of lake effect snow/rain showers
across our northern zones through Tuesday and generally fair
elsewhere. Next...ensemble clusters, including the operational
ec/GFS and Canadian models, point US toward Wednesday and
Thanksgiving day for our next potentially strong system to deal
with. Timing, strength and position of this system is all over the
place with a general tendency for a track again through the western
Great Lakes. That would suggest temperatures leaning on the warmer
side, or at worst marginal, for rain or snow showers depending on
time of day and change of airmass. To sum it all up...rather
unsettled for most days next week, but not unusually cold.
Aviation /12z Wednesday through Sunday/...
northwest flow is increasing and will reach to about 5-10 knots
later today with gusts into the teens. Lake moisture is trapped
under a developing subsidence inversion as a high pressure
ridge slowly builds in from the southwest. With the northwest
flow increasing, More Lake moisture will get involved which
along with a lowering of the inversion will get all terminals
into fuel alternate at times except krme only barely into MVFR.
Spotty sprinkles can also be expected for kith-kbgm this morning
to midday courtesy of combined influences of Lake Ontario and
Cayuga Lake, during which the ceiling will dip into IFR at times.
Trapped moisture under the subsidence inversion, as high
pressure passes, will keep ceilings fairly stagnant tonight;
with fuel alternate to IFR at kith- kbgm, MVFR to fuel alternate
kavp-kelm-ksyr, and minor MVFR krme.
Thursday...lingering MVFR-to-fuel alternate ceilings for
several terminals morning to midday, but improving to VFR.
Thursday night through Friday...restrictions likely in lower
clouds and rain showers as low pressure system passes.
Friday night...snow showers/flurries could bring restrictions,
mainly the New York terminals. Kavp perhaps an MVFR ceiling.
Saturday night through Sunday...system with snow-rain mix may
pass through the region with associated restrictions.