Scientific Forecaster Discussion
fxus61 kbtv 191743
Area forecast discussion
National Weather Service Burlington Vermont
1243 PM EST Fri Jan 19 2018
a ridge of high pressure extending from the upper Ohio Valley
northeastward into New York and New England will bring
seasonable and relatively quiet weather conditions today and
through the weekend. Variably cloudy skies are expected. A few
flurries are possible this morning, and across the northern
mountains over the weekend. A more significant storm system is
expected to affect the region by Monday night into Tuesday, with
the potential for substantial mixed wintry precipitation.
Near term /through Saturday/...
as of 1236 PM EST Friday...clouds, clouds, and more clouds
continue to prevail across our cwa this aftn. Have updated to
increase cloud cover thru this aftn and bump temps down several
degrees. Expecting highs mid 20s to lower 30s with developing
south/southwest winds at 10 to 20 knots.
Just a few lingering snow showers remain across Vermont's
Northeast Kingdom at 1145z as 700mb trough axis has shifted ewd
into New Hampshire. Abundant low clouds remain in the wake of the shortwave
trough, so main change with the sunrise update was to reduce
pops thru the remainder of the morning. Still anticipating 2-M
temperatures to climb to near freezing for afternoon highs.
Previous discussion...a relatively quiet stretch of weather is
expected today through Saturday. Infrared imagery at 08z reveals a
well- defined mid-level vort crossing northern New York and Vermont early
this morning. However, overall moisture is limited with precipitable water
values only 0.2-0.3". Some limited influx of low-level moisture
is occurring owing to low- level SW flow from Lake Ontario. This
combined with seeder-feeder processes (with lower stratus deck
in place) will result in some scattered snow showers to the
region through mid- morning, but any accumulation should be
limited to a half inch or less. Even after the mid-level
shortwave passes to the east, lower stratus deck will generally
remain in place with inversion 875-800mb layer helping to trap
low- level moisture/clouds in place. Best chance for sunny
breaks will be across the srn valleys. With 925mb temps warming
to -6 to -7c, should see high temperatures in the upper 20s to
lower 30s this afternoon.
The south to southwesterly gradient flow picks up tonight with
sfc low passing well to the north across central Quebec. Will
see temps fall early, but then slowly warm after midnight with
well-mixed conditions and general warm air advection regime setting up. Lows
generally 20-25f, except a few degrees warmer in the Champlain
and St. Lawrence valleys. Winds tonight generally around 10mph,
except 10-20 mph in the Champlain and St. Lawrence valleys with
some gusts up to 30 mph possible from the Champlain Valley wwd
across nrn New York.
Weakly cyclonic mid-level flow along the Intl. Border on
Saturday may bring a few flurries or snow showers to the
northern mtns, especially around Jay Peak. Otherwise, looking
for mostly cloudy skies with generally west winds 10-15 mph. May
see some downsloping resulting in best chance for sunny breaks
in the srn Champlain Vly/wrn Rutland County, and also east of
the green mtns into the CT River Valley. Continued moderation of
temps expected, reaching the upper 30s to lower 40s.
Short term /Saturday night/...
as of 403 am EST Friday...in the wake of the weak cyclonic mid-level
flow, a rather weak cold front moves across the area during the
day on Sunday. Outside of a few isolated snow showers, not much
is expected out of this system except for a slight cooldown
from saturday's high temperatures. Look for accumulations to be
minimal and primarily across the higher elevations. Look for
lows Saturday night in the mid to upper 20s and highs on Sunday
in the mid 30s.
Long term /Sunday through Thursday/...
as of 403 am EST Friday...temperatures begin to warm again on Monday
ahead of a fairly deep low moving across the Great Lakes and
into Ontario sometime Tuesday.
Models are coming together on timing, with the GFS still running
slightly faster than ECMWF, but the overall idea remains the same. A
warm front moves in later in the day on Monday into Monday night.
This is followed by a stronger cold front on Tuesday
afternoon/evening. Both the GFS and European model (ecmwf) suggest a widespread mixed
precipitation event, as the cold air on the surface will be tough to
scour out. General light snow to starts late on Monday, a good
amount of sleet and perhaps areas of freezing rain early Tuesday
morning before switching to rain during the day and ending as snow
and some possible mix Tuesday night. Still, this far out locking
into particular locations or amounts for sleet/freezing rain is a
bit premature as the forecast will continue to change until we get
closer to the event. Still, on the bright side, with this looking to
be much cooler than last week's event, Hydro looks to be less of a
concern but still bears monitoring as we still have several ice jams
in place across the forecast area.
After this system, Wednesday and beyond look rather quiet and
colder, though a snow shower or two are not out of the question.
Look for highs in the long term in the 30s with Tuesday touching the
lower 40s in the valleys and overnight lows in the 20s to teens
through Tuesday and in the single digits beyond that.
Aviation /18z Friday through Wednesday/...
through 18z Saturday...conditions vary between MVFR at slk/mpv
and VFR at mss/btv/pbg and pbg. Based on upstream obs and rap
sounding data, expect periods of IFR cigs to develop at slk this
aftn...before slowly lifting to MVFR again this evening.
Elsewhere...soundings show plenty of low level moisture in
developing southwest low to mid level flow...resulting in mainly
VFR cigs at pbg/rut/btv with lingering MVFR at mpv. Low level
jet of 45 to 60 knots develops overnight into early Saturday
morning...with localized gusts btwn 25 and 30 knots likely at
slk/mss and btv. Elsewhere...low level wind shear with areas of
moderate turbulence can be anticipated overnight into Saturday
morning. Mainly VFR conditions Saturday will trend toward MVFR
and eventually IFR cigs by 00z Sunday.
Saturday: mainly VFR, with local MVFR possible. Slight chance
Saturday night: mainly MVFR, with areas VFR possible. Slight
Sunday: mainly MVFR, with local IFR possible. Slight chance shsn.
Sunday night: mainly VFR, with local MVFR possible. Slight chance
Monday: mainly MVFR, with areas VFR possible. Chance snow.
Monday night: MVFR and IFR. Definite sn, definite ra, definite
pl, definite freezing rain.
Tuesday: mainly MVFR, with local IFR possible. Likely rain.