FXUS61 KBTV 212339
Area Forecast Discussion
National Weather Service Burlington VT
739 PM EDT Tue Mar 21 2023
A mid level warm front is approaching from the southwest tonight,
drawing more clouds into the region. High pressure over the
western Atlantic will promote mild air ahead of our next
weather system on Thursday. Well above freezing temperatures
even in higher terrain will support a rainy period on Thursday.
Below normal temperatures will settle back into the region on
Friday ahead of an elevationally dependent snowstorm anticipated
for the weekend.
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 728 PM EDT Tuesday...Very quiet night tonight, with only
small adjustments made to temperatures this update. The current
forecast remains on track.Previous discussion follows below.
Previous Discussion: The best forcing for snow showers
across our northern zones is currently occurring just behind a
decaying surface cold front. Throughout the day, model guidance
tended to have too much low level moisture which allowed for
precipitation to be more widespread than reality. For much of
the afternoon, snow showers were isolated to high elevations,
but finally is beginning to expand across the northern tier of
Vermont counties looking at glaciation of clouds in the Day
Cloud Phase GOES-16 satellite product. With the weak lift and
limited moisture, precipitation amounts will be very light.
Otherwise, increasing moisture associated with a mid-level warm
front will bring cloud cover from central New York into the
region tonight. This scenario will limit low temperatures
tonight in an otherwise favorable environment for radiational
cooling. As such, lows look to be mainly in the 20s. However,
have continued the idea of northeastern Vermont being colder,
where skies will clear overnight with light winds nearer to
Canadian high pressure nosing southward.
No precipitation chances areawide from roughly midnight to
midnight as ridging aloft occurs with surface ridging building
in the western Atlantic. As such, temperatures should trend
warmer in the higher terrain and remain mild at lower
elevations. Highs again will be well into the 40s at lower
elevations with some 50 degree readings favored across the lower
Connecticut River, Champlain, and Winooski River valleys. Cloud
cover will tend to lower late in the day as cyclonic flow slides
into our region, but forcing for precipitation looks meager.
Light winds will trend southerly from east to west as the
Atlantic high pressure area drifts farther east. At the same
time, by late tomorrow night, precipitation chances will increase
from west to east. Expect scattered rain showers to race
eastward associated with a frontal wave advancing out of the
Midwest. Steadier rain may arrive by daybreak but most of it
will occur on Thursday.
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
As of 328 PM EDT Tuesday...Low pressure tracking well north of the
region near James Bay will lift a warm front through the region
Thursday morning and a cold front Thursday evening. This combined
with shortwave energy travailing eastward along the boundary
originating from a decaying upper trough over the northern plains
will provide enough dynamical support to produce light to moderate
rain through the day with snow levels rising above the mountain
tops. Showers taper off Thursday night as the cold front moves south
of the forecast area, and could end as a brief period of snow,
especially across the higher terrain where a dusting to an inch is
possible. The more moderate rains look to be along the international
border where storm total QPF will range from 0.5-0.75", with
0.25-0.33" across central/southern zones. Post frontal passage, high
pressure will build into the region for Friday, but skies will be
slow to clear. Temperatures will cool back below seasonal norms for
Thursday night and Friday with lows in the mid 20s to low 30s, and
highs in the mid 30s north to lower 40s south.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 328 PM EDT Tuesday...Heading into weekend confidence is
increasing that we`ll see a strong low pressure system impact the
region with models coming into better agreement and pointing towards
an elevationally dependent snow storm. The overall synoptic setup
remains unchanged with low pressure developing over the lower
Mississippi River Valley Friday night, then tracking into Ohio
Valley by Saturday morning, and northward through the Great Lakes
Saturday/Saturday night. Secondary cyclogenesis looks to occur after
sunset Saturday evening along the mid-Atlantic coast which while
weak, around 1000mb, will aid in keeping colder air in place across
the Adirondacks and eastern Vermont, cold enough for snow to be the
dominant ptype, while the broader valleys below 1000 feet will be
warm enough for mainly rain. Given the recent trends in the guidance
towards a weaker coastal low, the best dynamics will remain
northwest of the region, with the heaviest QPF more closely tied to
the primary low. Nevertheless, Saturday through Sunday a blend of
model guidance supports widespread QPF amounts around a half inch,
with upwards of 0.75" across the higher peaks, which where the pytpe
is all snow could translate to a plowable snowfall (>4") with
several more inches possible in the higher elevations. Based on
marginal boundary layer temps in the 30s though, the expected snow-
to-liquid ratios are low (8-10:1), and could present some power
outage issues with heavy snow laden trees possible.
As the aforementioned system moves out Sunday night precipitation
will taper off as a brief ridge of high pressure builds in for
Monday. But the pattern looks to remain active heading into the
middle part of next week with a potential rinse and repeat mixed
rain/snow storm during the Tue/Wed timeframe.
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Through 18z Wednesday...VFR conditions are expected at all
terminals for the entirety of this forecast period. Some higher
clouds are moving in as a front moves into the area, but cigs
remain VFR. Winds will become light and calm tonight, and stay
that way for most of the TAF period as high pressure builds in.
Overall, fairly quiet and calm weather expected.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, Chance SHSN.
Thursday: MVFR/IFR conditions possible. Definite RA.
Thursday Night: MVFR/IFR conditions possible. Chance SHRA, Slight
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Saturday: VFR. Definite RA, Definite SN, Chance SHSN.
Saturday Night: Mainly MVFR and IFR, with local VFR possible.
Definite RA, Definite SN.
Sunday: MVFR and IFR. Likely RA, Likely SN, Chance SHRA.