Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 170818

Area Forecast Discussion
National Weather Service Burlington VT
318 AM EST Sun Nov 17 2019

High pressure will remain in control today, but the air mass will
moderate with high temperatures closer to freezing. Thereafter, low
pressure approaching southeastern New England will bring periods of
mixed wintry precipitation to the region Monday afternoon into
Tuesday. Ice accumulation of one to two tenths of an inch is
possible, resulting in potentially icy travel conditions. Mixed
precipitation may end as a period of snow or snow showers during the
day on Tuesday as low pressure exits north and east of New England.


As of 314 AM EST Sunday...After a very cold start, expect another
quiet day today as high pressure slowly slides east of the region.
The flow will gradually become more southerly as the ridge axis
moves to our east, allowing warmer air to spread over the area. This
along with plenty of sunshine will allow temperatures to peak into
the lower to mid 30s areawide. Clouds will increase late in the day
and overnight ahead of low pressure pushing northeast well off the
Mid Atlantic coast. Hence expect temperatures to be quite a bit
warmer than this morning; lows will range from the mid teens north
to the mid 20s south.

Things will deteriorate on Monday as the aforementioned low lifts
northeast, remaining off Cape Cod and east of the benchmark.
Meanwhile, an upper trough will dig to our west, placing us under
south-southwest flow aloft. Warmer air will lift over the very cold
air at the surface, which will result in the development of
precipitation. Note that much of the model guidance has slowed the
precip`s arrival time, likely due to the very dry airmass in place.
Have followed suit with this forecast, and believe that it will be
late morning or early afternoon before we see much hitting the
ground in our far southern areas, spreading northward through the
remainder of the day. Precip type is a tricky forecast as surface
temperatures will be marginal. Some guidance is going quite warm
(relatively), particularly in the wider valleys where some solutions
show temps reaching into the mid and even upper 30s. Feel this is
overdone given winds will be out of the north and the antecedent
cold airmass, so have stayed closer to the colder guidance, which
keeps temperatures in the lower 30s for most. Given the depth of the
warm nose aloft, therefore expect precip will start out as freezing
rain and remain so through the remainder of the day, with perhaps
some sleet mixing in at the onset. Some locations may change to rain
for a time during the afternoon, but current thinking is this will
be the exception as opposed to the rule. Ice accumulations of around
a tenth will be possible through Monday evening, highest in southern
sections where precip will start earliest.


As of 314 AM EST Sunday...Models continue to fluctuate back and forth
between the low track Monday night with the GFS now showing what the
NAM showed last night and vice versa. However, all numerical
guidance is coming into better agreement looking at the
thermodynamic profiles Monday night. While the exact amount of
precipitation and timing is going to be highly dependent on the low
track, it still looks some freezing rain is in store for much of
Vermont and parts of northern New York through about midnight.
Thereafter, we will be on the cold side of the upper level low and
should see enough cold air advection to allow the freezing rain to
transition to sleet and ultimately snow around sunrise. The
transition to sleet should last for about 2-3 hours as the stout
warm nose slowly erodes due to the weak cold air advection. With the
hydrometeors no longer able to fully melt, sleet looks like a good
bet for a few hours before sunrise. Finally, after sunrise on
Tuesday, precipitation will change over to all snow with the
thermodynamic profiles fully below freezing. Snow amounts should be
pretty minor with an inch or less for Northern New york and southern
Vermont with 1-2 inches possible across northern Vermont. Should we
transition away from sleet a little quicker, there could be slightly
higher snow accumulations. The combination of freezing rain, sleet
and snow will likely make for a slick morning commute on Tuesday.

Even with the cold air advection, high temperatures should still
warm into the lower to mid 30s on Tuesday. Snow showers will likely
continue through much of he afternoon across northern and eastern
Vermont as the surface and upper level lows continue to move
northeast. A brief break in the shower activity looks likely Tuesday
night with a weak shortwave ridge following the passage of the upper
level trough. Temperatures will struggle to cool off too much
Tuesday night with ample cloud cover residing over the region.
Overnight lows should only drop into the mid to upper 20s with is a
nice break from the single digit temperatures prior to the mixed
precipitation event.


As of 314 AM EST Sunday...Snow showers will redevelop early Wednesday
morning along the western slopes of the higher terrain across the
North Country as a decaying upper level low moves overhead. The best
snow showers won`t occur until Wednesday afternoon when the flow in
the mid and upper level switches to the northwest. This will help
support upslope snow showers on the western slopes of the Adirondack
and Green Mountains with blocked flow potentially allowing snow
showers to back into the Champlain Valley late Wednesday
afternoon/early evening. These showers will likely end by sunrise on
Thursday as we see high pressure briefly build across the region.
This period of drier weather will likely be short-lived with
rainfall expected to move into the North Country Friday morning
ahead of a developing upper level trough. Luckily, this event
doesn`t look like a mixed precipitation event with freezing rain
very unlikely. Nevertheless, as the day progresses on Friday, rain
will begin to transition to snow as the upper level low/trough
shifts eastward. We continue to remain in a progressive zonal
pattern aloft with weak impulses of shortwave energy as we head into
next weekend so period of light rain/snow showers look possible.
Temperatures will remain about 10 degrees normal during the long
term but hey it`s better than 20-30 degrees below normal.


Through 006Z Monday...VFR conditions expected through the
period with little in the way of any cloud cover and no
precipitation expected. Winds will generally be under 10 knots
through the period.


Monday: Mainly VFR, with local MVFR possible. Likely RA, Chance
FZRA, Chance PL.
Monday Night: Mainly MVFR, with areas IFR possible. Likely PL,
Likely FZRA, Chance SN.
Tuesday: MVFR/IFR conditions possible. Chance SN, Chance RA.
Tuesday Night: Mainly VFR, with local IFR possible. Chance SHSN.
Wednesday: Mainly MVFR, with areas VFR possible. Chance SHSN,
Chance SHRA.
Wednesday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHSN.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Chance SHSN.


Several low temperatures were set Saturday morning (11/16).
Montpelier reached 4 degrees to tie the previous record set in
1967. Plattsburgh reached 6 degrees to break the previous record
of 11 set in 1967. And St. Johnsbury (ASOS era only) reached 5
degrees, breaking the previous record of 10 set in 2003. FYI -
the longer standing evening co-op station at the Fairbanks
museum (SJBV1) recorded 3 degrees back in 1933 on this date.
Preliminarily...Montpelier, the St Johnsbury ASOS, Massena, and
Plattsburgh have broken low temperature records so far today.
However, this will not be official until the record reports are
sent later today.

Min Temp Records
Date    KBTV     KMPV     K1V4     KMSS     KPBG     KSLK
11-17   7|1924   5|1972   20|2017  12|1980  14|1972  -10|1933




NEAR TERM...Hastings
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