FXUS61 KBTV 210537
AREA FORECAST DISCUSSION
National Weather Service Burlington VT
1237 AM EST Thu Feb 21 2019
Snowfall will develop during the evening hours tonight as a warm
front lifts through the region. Snowfall amounts of 3 to 5 inches
will be common across the Green Mountains and eastern Vermont while
the rest of the area will generally see 1 to 3 inches of snow.
Temperatures will warm through the overnight period which may allow
for some sleet to mix in with the snow across southern vermont and
portions of northern New York. After highs warm into the upper 30s
to mid 40s on Thursday, temperatures will return back to normal
values for Friday and Saturday before another, and more potent,
warm front lifts northward and raises temps into the mid to upper
40s for Sunday. Ahead of this front, a a mix of snow, freezing rain
and sleet will be seen as temperatures are slower to cool at the
surface compared to just off the surface.
.NEAR TERM /UNTIL 1 PM THIS AFTERNOON/...
As of 619 PM EST Wednesday...No significant changes made to crnt
forecast with this update. Radar indicates bands of snow should
be lifting across our cwa this evening, however soundings and
obs show the low levels of the atmosphere are still pretty dry,
so this is falling as virga. NAM3km and GFS show column quickly
becoming saturated btwn 01-03z this evening, as better 850 to
700mb fgen forcing lifts from southwest to northeast across our
cwa. Expect snow to develop quickly with sfc vis to range btwn
1-2sm. A brief window of moderate snow is possible, especially
eastern/central VT btwn 04z-08z tonight, as moisture and lift
parameters align with the DZG area, per latest soundings.
Otherwise, all guidance shows a well defined mid/upper level dry
slot developing by 12z Thurs, with precip quickly dissipating.
However, noticing plenty of moisture below 5000 feet and
upstream obs showing lots of br/dz, so anticipating areas of
light drizzle/freezing drizzle on Thurs morning, especially over
the higher trrn. Temps continue to warm overnight with southerly
winds and clouds/precip advancing. All elements covered well in
Previous Discussion below:
A low pressure system located over Virginia will continue to
track northeastward heading into Thursday. As this happens, a
warm front will continue to lift northward toward the North
Country. Snowfall ahead of this warm front will move into
southern Vermont and portions of northern New York between 6 and
8 PM and into central and northern Vermont between 8 and 10 PM.
Snowfall amounts will be greatest across the eastern half of
Vermont (from the Green Mountains eastward) with greatest
frontogenetic forcing being closer to the low pressure system.
Snowfall amounts will range from 3 to 5 inches across eastern
Vermont with the rest of the forecast area seeing between 1 and
3 inches. As warmer air begins to filter in aloft behind the
warm front, there is the possibility for some sleet to mix in
with the snow. Warmer air aloft will begin to partially melt and
refreeze as it falls below the melting later across southern
Vermont and portions of northern New York after midnight
tonight. Based on the latest high-res guidance, they are
trending toward a "colder" solution which would minimize the
potential for mix but still looks favorable for some locations
to see some sleet mix in.
Temperatures for the large part will either be steady-state or
warming throughout the night with increasing warm air advection. In
addition, gusty southerly winds will develop toward morning which
will aid in mixing down warmer air. These gusty winds won`t be
particularly strong but will range between 20 and 35 mph. We get dry-
slotted pretty quick Thursday morning which will allow much of the
precipitation to end toward sunrise but a good westerly jet should
help showers linger on the western slopes of the Adirondack
Mountains as well as the northern Green Mountains. Thermal profiles
would support a mix of rain and snow which would lean towards more
rain during the late morning and afternoon hours and trend toward
mostly, if not all, snow as a cold front slides through late
Thursday. High temperatures on Thursday will range from the upper
30s to mid 40s with lows dropping into the 20s.
.SHORT TERM /1 PM THIS AFTERNOON THROUGH SATURDAY/...
As of 353 PM EST Wednesday...Friday starts out mostly dry with
some lingering upslope mountain snow showers under light
northwest flow. High pressure builds during the morning and the
weather should be fairly pleasant across the North Country with
temps near normal. Highs will be in the mid 30s Friday
increasing to the mid to upper 30s Saturday. Lows will be
slightly above normal with temps only in the low to mid teens.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 353 PM EST Wednesday...The quiet weather is short lived
as a system will push into the Great Lakes region Saturday night
and will bring widespread precipitation to the North Country
Sunday through Monday. A vertically phased low pressure system
will develop off the lee edge of the Rockies and push northeast
over the Great Lakes bring continued warm southerly flow. Based
on thermal profiles and soundings there`s going to be some dry
air in the lower levels that should lead to a fair bit of wet
bulb cooling initially. That should keep the precip type as all
snow for much of the evening before changing over to mixed
precip with some snow pellets and a 2-3 hour window of some
freezing rain before the temperatures warm well above freezing
late Saturday night into Sunday morning. Rain should continue
through much of the morning Sunday before a mid level dry slot
brings a brief lull in the action Sunday evening. Behind that a
cold front will slowly drop temperatures and precip will start
again as snow Sunday night into Monday morning.
Sunday afternoon there`s a strong low level jet that noses into
the Saint Lawrence Valley and thats going to potentially do two
things, one mix some stronger gusts into the Saint Lawrence,
and two shadow the Champlain valley. So total precip will likely
be significantly impacted by orographic effects.
High pressure then settles back in across the region Monday
night and Tuesday with another shortwave bringing some
precipitation mid week however temps should be cold enough to
mitigate any mixed precip concerns.
Based on the latest suite of guidance I`m not real bullish on
any flooding threats outside any river locations that are not
currently jammed with no channels. 24 hour rainfall totals
appear to be on the order of a half to three quarters of an inch
and absent quite a bit warmer temperatures I dont see significant
snow melt running off. So there shouldn`t be enough water added
to the basins to lift and break ice. That said, we`ll continue
to monitor for any changes and specifically for those locations
that already have an ice jam in place.
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...MVFR/IFR in light snow will continue across
the area for the next few hours before precip briefly transitions
to DZ/FZDZ before generally ending by 09-12Z with vsby lifting
to VFR and cigs remaining MVFR for the remainder of the night.
After 12Z, conditions slowly improve to VFR at all sites except
KMSS/KSLK where MVFR cigs will persist. Winds mainly southeast
except northeast at KMSS through the night before a shift to the
south/southwest after 12Z and becoming increasingly gusty
between 18-25kts at most sites through the period.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Chance RA, Chance SN.
Saturday Night: Mainly VFR, with local MVFR and IFR possible.
Likely SN, Definite FZRA, Likely RA, Likely PL.
Sunday: Mainly MVFR, with local IFR possible. Definite RA,
Sunday Night: Mainly MVFR and IFR, with areas VFR possible.
Likely RA, Likely SN, Likely SHSN.
Monday: VFR. Windy with gusts to 30 kt. Chance SHSN.
VT...Winter Weather Advisory until 10 AM EST this morning for