FXUS61 KBTV 240211
Area Forecast Discussion
National Weather Service Burlington VT
1011 PM EDT Thu Mar 23 2023
Cool and dry weather is expected on Friday as high pressure briefly
crosses the region. Then as a strong low pressure system passes to
our northwest, an elevationally dependent mixed precipitation and
snowfall event will unfold over the region Saturday into Saturday
night. Some light snow and ice accumulations are possible. After
lingering showers on Sunday, we turn towards drier weather early
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 1008 PM EDT Thursday...Precipitation has all but come to
an end as of 10 PM with just a few spits of rain across central
Vermont. Any lingering shower activity will dwindle quickly over
the next few hours with dry conditions expected by midnight. The
cold front continues to take it`s sweet time as it`s still
hugging the International Border near the St. Lawrence River.
The latest NAM3 and RAP model suites show the front becomes more
progressive over the next few hours which should bring a steady
drop in temperatures and dewpoints as winds shift to the
northwest. Ahead of this front, however, patchy dense fog
continues to plague portions of Vermont given the latest
rainfall, warm temperatures, and extensive snow pack. All signs
show this fog lifted behind the frontal passage.
Previous Discussion...Low pressure currently positioned just to
our north will continue to pull away to the east overnight and
Friday, with ridging following along behind. Widespread rain
this afternoon will taper to showers this evening and come to
an end early Friday as drier air spills in behind the low.
Temperatures will cool overnight as well, so rain may mix with
and/or change over to snow before finally ending, especially in
the higher terrain. Clouds will be slower to depart, and expect
we`ll have a fairly dreary start to the day Friday. Moisture
will continue to thin through the day though, so we`ll see
improving conditions with everyone getting at least some
sunshine before sunset. The ridge crests directly overhead
Friday night, resulting in light winds and at least some
clearing, though high clouds will begin to increase in western
areas toward daybreak Saturday ahead of our next system.
Temperatures tonight will bottom out in the mid 20s to lower
30s, and then we should warm up into the mid 30s to mid 40s on
Friday, perhaps even a bit warmer for those areas that get
sunshine. Friday night will be chilly under the ridge; lows in
the 15F to 25F are expected.
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 331 PM EDT Thursday...Still expecting a messy mix of wintry
precipitation, though as has been warned over the past couple of
days, the details continue to evolve. Main change has been for the
warm nose aloft to push further north, meaning more mix, and
potentially freezing rain, especially for southern sections/higher
Overall the expected set up remains the same, with an anomalously
strong low to lift up to our west. Precipitation will spread
northward into the area Saturday, but with dry air in place, it will
take a while before the column is able to saturate and precipitation
reaches the ground. Models continue to indicate a band of strong
frontogenetical forcing to lift northward late Saturday afternoon
into the evening hours, and this heavier precipitation will aid to
cool the column. Therefore, expect even in areas that warm above
freezing, any light rain will mix with/transition to snow,
particularly at higher elevations. With an 55+ kt 850mb southeast
jet, this first batch of precipitation will focus on the east-facing
upslope sides of the southern Greens and Adirondacks. These winds
will gradually turn to the southwest during the evening/overnight,
ushering in a warmer layer of air aloft. Valley locations may be
able to remain mostly rain as temperatures recover after initial
burst of heavier precipitation. But higher elevations should turn
over to more of a snow/sleet/freezing rain mix, especially
along/south of a Massena, NY to Montpelier, VT line. As a secondary
low starts to develop off the New England coast Saturday night,
temperatures will cool aloft, once again transitioning over to
mainly elevation-dependent rain/snow from west to east. At this
time, latest forecast calls for elevations below 1500 ft see less
than an inch of snow accumulation, with 1 to 4 inches possible above
1500 ft. Ice accumulations would be a glaze to around a tenth, with
the best chances for appreciable accretion in the central/southern
Greens and Adirondacks. However, we continue to stress that given
the complex scenario of elevation vs thermal profiles, these numbers
will likely change as the forecast evolves.
Also of concern for Saturday afternoon/evening will be the potential
for these higher winds to mix down; note the NAM in particular is
quite gusty, with 40-45kt mean-mixed layer winds. The western
downslope sides of the Greens/Adirondacks would be most susceptible
to gustier conditions Saturday afternoon/evening. However, as winds
turn to the west/southwest Saturday night, the St Lawrence Valley
and eastern sides of the higher terrain would see the higher gust
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 331 PM EDT Thursday...Some showers linger around on Sunday as
the double-barrel low system continues trek eastward. There is
potential for strong surface winds given strong low level
westerly/southwesterly flow. Precipitation will taper off by Sunday
evening as ridging starts to build in, giving us some quiet weather
for the start of the work week.
There is a lot of model disagreement regarding midweek and how it
plays out, but there is weakening support for a midweek system like
previous guidance was showing. At this point, continuing the trend
of SChc/Chc PoPs seems to make the most sense given the wide range
of possibilities and large amount of uncertainty. Still plenty of
time for model consensus to increase, but stay tuned to see how
everything will play out.
Temperatures look to remain fairly seasonable through the extended
forecast, with daytime highs in the mid 30s to mid 40s and overnight
lows mainly in the 20s.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Through 00z Saturday...Extremely up and down TAFs this evening.
With rain becoming more showery or scattered, the main vis
concern will be fog for the next few hours. Fog has already
developed in various spots across the forecast area, but the
question remains whether they will impact the airports and for
how long. It will likely be a very unpredictable few hours as
fog moves in and out of sites. Vis expected to drop to 1/4SM at
lowest in KMPV. Cigs will gradually lift throughout the period,
but this will be another timing issue with plenty of tempo
groups, as cigs will go up and down before going solidly VFR.
Lowest cigs will be around 300 ft AGL in KMSS, but like the
other sites, cigs will likely come up to VFR within the next 24
hours. By around 10z Friday, fog will probably not be a concern
anymore, either. Winds calm or southwesterly are expected to
turn westerly (KMSS) or northwesterly over the next 24 hours at
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with areas MVFR and IFR possible. Definite
RA, Definite SN.
Saturday Night: Mainly MVFR and IFR, with local VFR possible.
Windy with gusts to 30 kt. Definite RA, Definite SN, Definite PL,
Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA, Chance
Sunday Night: Mainly VFR, with areas MVFR possible. Slight chance
Monday: NO SIG WX.
Monday Night: Slight chance SHSN.
Tuesday: Chance SHSN, Chance SHRA.
As of 330 PM EDT Thursday...A low chance of river flooding will
be monitored for the late tonight into Friday morning period in
response to light to moderate rainfall with basin averages of
0.2" to 0.5" and snow melt up to 1". High dew points have helped
to ripen the snow pack with continued melting at lower elevations.
Therefore, modest to sharp river rises may occur by this evening
into Friday in the watersheds with runoff primarily due to snow