Scientific Forecaster Discussion
fxus61 kbtv 120820
Area forecast discussion
National Weather Service Burlington Vermont
320 am EST Tue Nov 12 2019
widespread snow and mixed precipitation will taper to light
snow showers and flurries by this afternoon into Wednesday
morning as low pressure exits east and much colder air pushes
into the region. Unseasonably cold and mainly dry weather then
persists across the area through much of the week before
temperatures moderate into next week.
Near term /through Wednesday/...
as of 311 am EST Tuesday...the forecast remains largely on
track for today as low pressure moves through interior southern
New England and into the Maritimes by this evening with pcpn
tapering off rather quickly by this afternoon. Surface low has
tracked a bit further north per most recent observational trends
with mixed pcpn/sleet line lifting as far north as kbtv for
several hours this morning. Snowfall rates have also been just a
tad lower than prior indications across northern New York/far NW Vermont
through 200 am. However, trends are for mid level fgen fields to
tighten sharply in this region as the sfc low passes so rates
into the 1 to 1.5 inch range are still expected within this
dynamically forced band as it shifts slowly east this morning.
As such, overall snow totals were lowered just slightly with
this package though the general theme of a 7-12 inch event along
and northwest of a Elizabethtown, New York to Burlington to Newport,
Vermont line still look reasonable at this point with some slight
variability. Further south and east a narrow band of 3-7 inch
accumulations should stretch across southeastern Essex, New York-
Addison-Washington-Caledonia-Essex counties, Vermont. Then
considerably less across south/southeastern Vermont where much of the
overnight hours has panned out with just light intermittent
mixed pcpn as advertised.
Temperatures will go nowhere today as strong cold thermal advection
kicks in behind the departing low and flow trends gusty northwest.
Generally looking at steady readings in the upper teens to lower 20s
north, and mid to upper 20s central/south with a few spot low 30s
far south. This is in close agreement with blended lamp/bias-
corrected lamp hourly data.
By tonight lingering flurries/light snow showers continue across
northern higher terrain with passage of upper polar trough. Occnl
light shsn/flurries also likely to the Lee of Lake Champlain where
lake induced cape values will exceed 500 j/kg. Some light/minor
accumulations possible in these areas. Low temperatures to bottom
out near or below records for the date - mainly in the positive
single digits to locally lower teens in the Champlain Valley (see
climate section below for records).
Any lingering morning light shsn/flurries then end on Wednesday as
surface high pressure builds into the area. Winds will trend light
over time with partly to mostly sunny skies expected by afternoon.
Very unusual cold persists for the second week in November with mean
925 hpa temps from -12 to -15c supporting afternoon maxima only the
upper teens to mid 20s (add +7c this time of year for a mixed pbl
Short term /Wednesday night through Thursday night/...
as of 319 am EST Tuesday...Wednesday night is going to be a bit
tricky when it comes to the overnight low temperature forecast. The
surface high will be situated across the north country for much of
the overnight period but we zonal flow aloft will begin to usher in
some moisture ahead of a low amplitude shortwave that will be
situated across the Ohio River valley. This should allow for cloud
cover to begin moving into northern New York just after midnight and
into Vermont shortly thereafter. This should help to limit
radiational cooling thus limiting our overnight low temps. In
addition, with an anomalously cold air mass moving over a Warm Lake
Champlain (48 to 50 degrees), we should see a thicker blanket of
clouds develop within close proximity to the lake. This would hinder
cooling further, especially across the northern Champlain Valley.
Overall, low temperatures Wednesday night will range from the lower
single digits in the northern Adirondacks and Northeast Kingdom to
the lower to mid teens across the Champlain and St. Lawrence
The aforementioned weak shortwave will get trapped across western
New York as the upper level trough begins to shear apart. Snow
showers will likely impact the St. Lawrence Valley late Wednesday
night through Thursday afternoon before the shortwave finally shears
out with the synoptic scale trough. Elsewhere, precipitation chances
will be near zero with the moisture and lift stuck a bit to our
west. Thursday will also be noticeably warmer than Tuesday and
Wednesday as the flow backs from the northwest to the west and
allows some weak warm air advection to push into the north country.
This will yield temperatures in the mid 20s to lower 30s which will
still be about 15 degrees below normal. Following the warmer
temperatures on Thursday, temperatures Thursday night will also be
about 10 degrees warmer than Wednesday night with lows generally in
the lower to upper 20s.
Long term /Friday through Monday/...
as of 319 am EST Tuesday...a reinforcing shot of cold air will
descend upon the north country during the day on Friday and help
drive a weak cold front through the region. Snow showers are likely
to develop ahead of the frontal boundary will could yield some light
accumulations across northern New York and Vermont but should be
rather progressive and push through very quickly. By Saturday
morning, we should be under the influence of a strong surface high.
When you could this with the reinforcing shot of cold air, the
clearing skies under the high should allow for another burst of
unseasonably cool temperatures Saturday night. Lows once again will
be in the mid single digits to the mid teens.
Good news for those not ready for the early season cold snap: an end
appears to be in sight. Following the cold front Friday/Saturday,
temperatures begin to warm for the second half of the weekend and
the warming trend will continue into next week. Deterministic and
ensemble guidance are in remarkably good agreement showing ridging
developing over the East Coast as the longwave trough sets back up
over the central US. This should allow US to return to near seasonal
temperatures will keeping US on the dry side for much of next week.
Aviation /08z Tuesday through Saturday/...
through 12z Wednesday...widespread IFR expected through 12-15z
as low pressure brings steady snowfall and/or mixed pcpn to the
region. Highest confidence for mixed pcpn to occur at kmpv and
krut through 10z with heaviest snowfall and visibilities locally
to 1/2sm at other terminals. Winds generally northerly from
5-10 kts through 12z with some variability. After 12z snow
tapers off rather quickly from west to east, generally ending in
the 14-18z time frame as cigs trend MVFR or VFR depending on
terminal. Winds gradually back to west/northwesterly at trend
gusty to 20 kts by afternoon/early evening.
Wednesday: VFR. No sig weather.
Wednesday night: VFR. Chance shsn.
Thursday: VFR. Slight chance shsn.
Thursday night: VFR. Slight chance shsn.
Friday: MVFR. Chance shra, chance shsn.
Friday night: mainly VFR, with local MVFR possible. Slight chance
Saturday: VFR. No sig weather.
below are daily record minimum temperatures for November 13 and 14.
November 13 November 14
Burlington: 15 (1986) 10 (1996)
plattsburgh: 10 (1986) 12 (2004)
montpelier: 10 (1986) 5 (2018)
Saranac lake: 2 (1905) -4 (2018)
massena: 12 (1986) 8 (1971)
Vermont...Winter Storm Warning until 1 PM EST this afternoon for
Winter Weather Advisory until 1 PM EST this afternoon for
New York...Winter Storm Warning until 1 PM EST this afternoon for