109
FXUS61 KBTV 160525
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1225 AM EST Thu Jan 16 2025

.SYNOPSIS...
Any lingering snow showers will end this evening with temperatures
cooling back into the single digits and lower teens. On Thursday a
weak system will produce additional light snow showers with only
minor snow accumulation expected as temperatures warm into the 20s.
Friday is quiet, before mainly mountain snow showers overspread the
area on Saturday with gusty south winds. Temperatures will warm into
the 30s, but with the brisk winds it will feel much cooler.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 1204 AM EST Thursday...The focus on this update was once
again ensuring we are adequately indicating the influence of
cloud cover on temperatures. The Ogdensburg area has remained
warmer than surrounding environs as the lake influences the
clouds. Widespread precip has also come to a halt in our CWA,
and we adjusted PoPs down as a result.

Previous discussion...Well when will the localized upslope snow
showers finally dissipate is the challenge this evening,
followed by temps. A retired NWS employee reported another 2.0
of fluff today for an event total of 12.6 inches since last
night in the North Underhill area and a solid 10 inches at Lot 1
at Smuggs earlier this morning, while only a trace has fallen
here at BTV. Based on qpf and snowfall, ratios have been running
in the 40/50 to 1 range.

GOES-16 mid lvl water vapor shows weak embedded s/w dropping south
acrs n-central VT this aftn, with drier air angling into northern
NY/SLV with some breaks in the overcast per latest vis satl. Any
lingering snow showers wl dissipate this evening as moisture
decreases and winds become light and variable, which wl minimize
lift from the upslope flow. In addition, sfc dwpts have fallen back
into the single digits as drier air advects into our region on
westerly flow, so any additional accumulations wl be light with no
impacts. If pockets of clearing continue overnight, localized much
cooler temps are possible, especially western dacks/parts of the
SLV. Have temps ranging from near 0F to lower teens, but would not
be surprised if some locations drop below zero overnight, given
fresh snow pack and some breaks in the overcast.

Our next weak clipper like system with limited moisture is already
evident on water vapor imagery acrs the northern Plains/western
Great Lakes. This mid/upper lvl trof wl pass directly overhead btwn
21z-03z Thurs evening along with lobe of mid lvl moisture and some
weak forcing associated with s/w energy. Guidance suggests only very
light qpf as system has limited deep layer moisture and modest
forcing. I have bumped pops into the high chc range as I feel some
light snow is likely, especially northern NY into the mtns of
central VT. Any snowfall wl be a dusting to 2 inches at best. Highs
on Thurs are in the 20s with developing southerly flow and lows drop
back into the teens on Thurs night with some lingering mtn snow
showers possible thru 06z.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 251 PM EST Wednesday...Quiet weather conditions are expected
Friday with surface and upper- level ridging building in from the
south. Morning cloud cover will scatter out going into midday,
leading to partly to mostly sunny conditions during the afternoon.
Forecast highs are in the mid 20s to low 30s Friday with light
winds. As the anticyclone shifts east overnight, mid and upper
level clouds will spread into the area ahead of an advancing trough
to the west. Pressure gradient will increase overnight and a 40+
knot swly low level jet will move overhead by early Saturday
morning. Expect some breezy south winds to develop overnight (10 to
20 mph), mainly at higher elevations and locally channeled up the
Champlain Valley. MOS guidance suggests low temperatures for Friday
night will be observed early in the night, followed by gradual
warming into the morning as southerly flow increases.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 251 PM EST Wednesday...Southerly low-level jet will crest
overhead early to mid-day Saturday. Local topographical enhancement
of the jet over the Champlain Valley will result in 925 to 975 mb
south winds up to 45 knots. This low-level jet, right at the bottom
of the inversion level as per forecast soundings, will translate to
gusty winds 30+ mph reaching the surface over the Champlain Valley.
Have utilized some of the higher wind guidance including the NBM
90th percentile for winds during this timeframe based on the setup,
especially locally over the Champlain Valley. The resultant warm air
advection will allow surface temps Saturday to rise to above
freezing nearly everywhere, topping out in the mid to upper 30s.

For the latter half of the day into Saturday night, a cold front
associated with a low pressure system lifting northeastward through
Quebec will move through our area. Along with the front will be a
brief shot of precipitation followed by much colder temperatures
going into next week.

The initial shot of precipitation associated with isentropic ascent
and loosely organized southern-stream shortwave energy will begin
Saturday afternoon into Saturday night. With the low-level jet
still in place at this time, expect precipitation to be highly
localized based on terrain, with southern and southwestern slopes of
the Adirondacks and the southern Greens seeing some precipitation
while northern slopes and the Champlain Valley will see little if
anything. Snow levels will be around 500 feet, although
accumulations will be initially difficult to achieve due to the
effects of the winds on the snow crystals. The actual cold front
will move through Saturday night, which will drop snow levels to
zero and shift the favored precipitation areas to the northwest
facing slopes. The passage of the cold front will also be marked by
rapid moisture loss in the mid and upper-levels, which will limit
additional accumulations. Nonetheless, expect some lingering snow
showers over northwestern slopes into midday Sunday while a layer of
low-level moisture is still present.

Looking ahead to next week, the main story will be the cold
temperatures expected as an arctic air mass settles in. With 850 mb
temps falling towards -25C by Tuesday morning, this has the
potential to be the coldest air mass of the season. Coldest
temperatures will be observed Monday into Tuesday, when
probabilities of overnight lows below 0 deg F are between 60 and 95
percent as per probabilistic guidance. With at least a modest
pressure gradient in place most of next week, winds of even 5-10 mph
will create dangerously cold wind chills to those outside. Please
prepare in advance for this upcoming cold spell.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
VFR has overspread all TAF sites in our CWA. These conditions will
persist into the day tomorrow. By tomorrow afternoon we could see
some scattered snow showers that reduce visibilities into the MVFR
or even IFR criteria. The chance for occurrence is greatest west of
Lake Champlain.

Outlook...

Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. Chance SHSN,
Chance SHRA.
Saturday Night: Mainly MVFR, with areas VFR possible. Chance
SHSN.
Sunday: Mainly MVFR, with areas VFR possible. NO SIG WX.
Sunday Night: Mainly VFR, with areas MVFR possible. Slight chance
SHSN.
Martin Luther King Jr Day: Mainly VFR, with local MVFR possible.
NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Taber
NEAR TERM...Langbauer/Storm
SHORT TERM...Duell
LONG TERM...Duell
AVIATION...Langbauer