Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
203 PM EST Tuesday Dec 10 2013
mostly cloudy skies will persist through Thursday with temperatures
gradually trending colder. Westerly winds will bring a few snow
showers today...mainly to the northern Adirondacks. An Arctic
front passing through the region Wednesday afternoon and night
will bring more widespread snow showers or a brief snow squall.
This Arctic front will usher in very cold air for Thursday with
high temperatures only in the teens.
Near term /until 6 PM this evening/...
as of 1224 PM EST Tuesday...clearing coming into northern New York
and northwest Vermont as the low pressure well off the New England
coast shifts northeastward. Even with the low sun angle, there is
some weak instability developing in the "sunny" areas, resulting
in some bubbling of small cumulus, which in turn is resulting in a
Otherwise the overall forecast still on track for the afternoon.
Overall lots of clouds and a few flurries/light snow showers.
Temperatures are still slowly sinking as we've already hit our
Have maintained low chance probability of precipitation in the central greens thanks to
some weak orographic lifting.
Short term /6 PM this evening through Thursday/...
as of 344 am EST Tuesday...westerly flow and cold advection across
the Great Lakes will continue tonight into Thursday. The result
will be plenty of clouds downwind across the north country. Stayed
close to MOS guidance for temperatures...which will trend
gradually colder through the period. Best chance for snow showers
shaping up to be Wednesday afternoon and evening. An Arctic
boundary will interact with existing lake effect snow bands to
bring an increased chance for more widespread snow showers or snow
squall activity during this period. Snow accumulations of only 1-2"
expected with the front...but it may fall quickly and have some
travel impacts. Low temperatures tonight will be mainly in the
teens...with highs Wednesday in the 20s. Behind the Arctic front
Wednesday night...temperatures will plummet into the single digits
despite cloud cover. Normally colder portions of Adirondacks and
Northeast Kingdom may fall a bit below zero. Core of the cold air
will be begin retreating a bit Thursday afternoon...but with 850
mb temperatures only rebounding to around -15c by days end...we can only
look for high temperatures in the teens. Chance of snow showers Thursday
will be highest over the southern Saint Lawrence valley and the
Adirondacks as flow becomes westerly once again...allowing for
some lake effect moisture to return.
Long term /Thursday night through Monday/...
as of 344 am EST Tuesday...beginning of this period...forecast area still
influenced by cyclonic polar west-northwest middle level flow with a surface trough
hanging across eastern Great Lakes into northern New York that lake effect snow
machine will be continuing mainly S of forecast area but northern reaches could
effect southern St lwrnc/Franklin counties but nothing too signficant at
The main focus of this longer term period is the eventual evolution
of southern and northern stream energy this weekend. The Gem/European model (ecmwf) and GFS are
all in rather good agreement of eventual phasing...timing of such is
Currently...it looks like GFS/Gem are in agreement of erlr phasing
and arrival of precipitation which erlr wpc medium range guidance has followed.
In my forecast grids...snow will be arriving during the course of Sat
afternoon with Sat night through midday Sunday having its biggest impact with
gradual diminish to snow showers sun aftn/ngt.
At this time...it appears cold air is deeper...stronger and shld stay
entrenched for all snow. Quantitative precipitation forecast amts suggest the potential of the
biggest widespread snowfall of this Young season...which isnt hard
If traveling plans this weekend...please closely monitor future
forecasts and plan accordingly.
Aviation /18z Tuesday through Sunday/...
through 18z Wednesday...generally VFR across the region, though a
few light snow showers/flurries are found here and there and they
are producing a momentary drop to MVFR. Have added a few "vcsh" in
some taf sites based on current radar trends.
Persistent westerly flow for the rest of today and overnight
should keep the lots of clouds across the area, but only minimal
chances of any flurries/light snow showers.
Come Wednesday, flow veers southwest ahead of a front. Expect snow
showers to spread across northern New York by 18z...elsewhere after that point.
Outlook 18z Wednesday through Sunday...
18z Wednesday through 12z Thursday...MVFR and IFR at times as
Arctic front brings scattered snow showers.
12z Thursday through 18z Saturday...generally VFR with high
18z Saturday Onward...increasing chances of MVFR/IFR in snow.