Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kbtv 191729 
afdbtv

Area forecast discussion
National Weather Service Burlington Vermont
1229 PM EST sun Nov 19 2017

Synopsis...
strong low pressure will sweep across the area today with
strong and gusty winds as temperatures trend colder and steadier
rains taper to snow showers. Relatively quiet weather is
expected from Monday Onward through much of next week with early
indications suggesting a good travel day for the upcoming
Thanksgiving Holiday.

&&

Near term /through Monday/...
as of 1126 am EST Sunday...continue minor tweaks to address
sharply falling temperatures with the front and starting change
from rain to snow as it looks like 37-38 degrees is good enough
for snow. Rest of forecast remains untouched as precipitation
continues to decrease over northern New York and gusty
winds/falling temperatures continue elsewhere.

Prior discussion...
deepening 982 mb surface low near kart early this morning will
take an expected climo track through the St. Lawrence Valley
today before exiting quickly toward the Gaspe Peninsula by this
evening. The forecast is predicated on this scenario and largely
follows persistence from our prior forecast showing steadier
rains ending from southwest to northeast this morning as the
system's sharp cold front sweeps across the area. Strong cold
thermal advection will quickly follow the front as winds shift
west/northwesterly and trend quite gusty under a deeply mixed
boundary layer. Perusal of area forecast soundings continue to
support maximum gusts from 25 to 40 mph with a few gusts near 45
mph along the eastern slopes of the Adirondack and Green
Mountains where isolated power outages will be possible. This
seems plausible given robust Post- frontal 3-hourly pressure
rises from 5 to 9 mb from late morning into this afternoon. As
colder air pushes into the area, lingering precipitation will
trend more showery in nature and quickly transition to snow
across northern New York and the northern mountains of Vermont where minor
accumulations from a dusting to 2 inches or so will be possible.
Little accumulation is expected in the Champlain and lower CT
river valleys. Temperatures will take on a non-diurnal trend and
will be somewhat challenging as readings gradually fall into
the afternoon. Using a blend of our prior forecast and this
morning's btv 4km WRF output supports morning highs in the 30s
across the dacks/slv and lower to mid 40s in Vermont before readings
falling into the upper 20s to lower 30s for most spots by early
evening.

By tonight any lingering snow showers across the northern high
terrain will gradually end as brisk northwest flow abates slightly.
Any additional accumulations will be minor at best as low
temperatures bottom out from the mid teens to lower 20s under
variably cloudy skies. Brisk and seasonably cold weather then
continues into Monday, though outside a few mountain flurries dry
weather is expected as surface high pressure builds east from the
Great Lakes and skies gradually trend partly sunny by afternoon.

&&

Short term /Monday night through Tuesday/...
as of 400 am EST Sunday...Monday night and Tuesday will feature
drier weather, and increasing return flow bringing temps back
above seasonal normals for Tue. Will still have a surface ridge
over the area Monday night, therefore cool temps, clear skies
and light winds expected. Increasing southerly return flow on
Tue as ridge moves east of the region. Temps will edge into the
50s on Tue.

&&

Long term /Tuesday night through Saturday/...
as of 400 am EST Sunday...a cold front will cross our forecast
area Tuesday night bringing scattered light rain and snow
showers to the area and colder air for Wed. Have mentioned
chance pops across our northern New York zones for Tuesday
night, then chance across northern Vermont on Wednesday. Not a
lot of moisture with this front as low passes well north of our
region, but think we'll see at least some scattered light
showers. Rain showers will end as light mountain snow showers.
We return to dry weather again for Thursday through Friday.
Friday night through Saturday night will be our next chance at
some weather. Another low will pass north of the region bringing
scattered rain and snow showers to the area once again. GFS and
European model (ecmwf) still differ quite a bit with track and timing of the
low. Temperatures will trend back below normal for much of the
week with a few chances for precipitation, but nothing
significant.

&&

Aviation /18z Sunday through Friday/...
through 18z Monday...mix of VFR/MVFR as low pressure has lifted
northeast and sharp cold front has passed area as of 17z Sun.
Mountain snow showers will bring about MVFR to possible IFR in
cigs/vsby thru 20-21z then improvement to VFR. It will be windy
from west at 13-20kts with gusts 23-32kts through 00z Monday
then backing off slightly to 10-15kts g20-25 kts thru 18z Mon.

VFR tonight and Monday with gradual decreasing cloudiness
through the remainder of the period.

Outlook...

Monday night: VFR. No sig weather.
Tuesday: VFR. No sig weather.
Tuesday night: mainly VFR, with local MVFR possible. Chance shra,
chance shsn.
Wednesday: mainly VFR, with areas MVFR possible. Chance shsn,
slight chance rain showers.
Wednesday night: mainly MVFR, with areas VFR possible. No sig weather.
Thanksgiving day: mainly VFR, with areas MVFR possible. No sig
weather.
Thursday night: mainly VFR, with areas MVFR possible. Chance
shsn.
Friday: mainly VFR, with areas MVFR possible. No sig weather.

&&

Marine...
as of 1125 am EST Sunday...a lake Wind Advisory remains in
effect for today. Winds have turned to the northwest and are in
the 25 to 35 knot range with gusts approaching 40 knots. This
will create significant wave heights in the 2 to 5 foot range
with a moderate chop. These conditions may prove hazardous to
those operating small craft, especially on the eastern half of
the Broad Lake and in Vermont bays/inlets with westerly
exposures. Gusty northwest winds will abate slightly later this
evening into Monday.

&&

Btv watches/warnings/advisories...
Vermont...none.
New York...none.

&&

$$
Synopsis...jmg

National Weather Service Glossary of Abbreviations