Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 291935
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
335 PM EDT Wed Mar 29 2017

.SYNOPSIS...
Deep low pressure over central Quebec will continue to provide
abundant cloud cover to the North Country today, along with
areas of fog and drizzle this morning, and some scattered rain
and snow showers across north-central Vermont this afternoon. A
brief period of sunnier and drier conditions is expected on
Thursday as a ridge of high pressure builds over the region, but
unsettled weather returns for the end of the week and into the
weekend, as another storm system will bring valley rain and
mountain snow Friday into Saturday.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 718 AM EDT Wednesday...Deep low pressure over central
Quebec this morning continues to provide abundant low level
moisture to the North Country in the form of areas of cold
drizzle and fog with current temps ranging through the 30s. Cold
air advection continues through the day on northerly flow, and
while precipitation chances generally wane across the majority
of the region, additional shortwave energy rounding the base of
the upper trough will skim along the international border
maintaining the threat for scattered valley rain and mountain
showers across central and northern portions of Vermont through
the afternoon. Abundant cloud cover will persist through the day
as well, keeping temps in the mid 30s to low 40s in the valleys
while the higher summits gradually fall through the 20s.

For tonight, the upper trough finally begins to swing east of
the area with surface high pressure and and upper ridging over
the Great Lakes and Ohio Valley edging ever so slowly eastward
towards the region. Low levels finally begin to dry out with
subsidence aloft winning out, so a gradually clearing of skies
is expected though mainly after midnight with valley locales
clearing the most, mountain areas less so. Lows will range
mainly in the 20s with some teens in the Adirondacks.

Thursday will be the best day of the week as the aforementioned
high centers over the Northeast with skies continuing to clear
through the day. Unfortunately temps won`t really change to much
as weak cold air advection will continue on light northerly
flow, but we should realize widespread highs in the low/mid 40s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 341 AM EDT Wednesday...Most active period of weather then
affects the region by late Thursday night and especially Friday
into Friday night as upper closed energy tracks east from the
Ohio Valley into the Mid Atlantic region. The forecast remains
quite complex in regard to precipitation timing, amounts and
type with lower boundary layer thermal profiles playing a
critical role through the period. This is not uncommon with
early spring systems with subtle changes of 1 to 2 degrees
either way potentially leading to large differences in sensible
weather. For now will maintain our prior idea of snows arriving
into our southwestern counties later Thursday night into mid
morning on Friday before a transition to all rain in lower
elevations, or rain/snow mix from 1000-2500 feet on Friday as
precipitation shield advances into the remainder of the forecast
area. At higher elevations above 2500 feet p-type may remain as
all snow. Negligible amounts of sleet or freezing rain is
expected. Lows Thursday night mainly in the 20s with afternoon
highs on Friday from 35 to 40 below 1500 feet and 30 to 35 above
that level.

Bulk of precipitation then affects the area Friday night as warm
thermal advection aloft will be peaking and as thermal profiles cool
slightly a transition to all snow is expected after midnight.
Amounts may be a bit tricky as flow trends southeasterly and some
slight shadowing effects may occur. Time will tell. I was also
cautious in leaning too high on our QPF given known model high bias
during warm thermal advective events. Nonetheless the potential will
exist for a light to moderate wet snow accumulation in many areas
with higher amounts possible in elevated southern terrain. Did lean
on the milder side of guidance given clouds and lack of appreciable
low level advection - mainly lower to mid 30s (upper 20s at
elevation). Please see our winter weather page at
www.weather.gov/btv/winter for specific accumulation forecasts and
probabilities.

By Saturday widespread light snows taper to scattered rain/snow
shower activity as system exits the Mid Atlantic coast and
gradually loses influence. Any additional snow accumulations
will be minor as late day temperatures top out in the upper 30s
to lower 40s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 335 PM EDT Wednesday...A low pressure area will off the
southern New england coast early Saturday. Expecting steady
precipitation Saturday morning to taper off by Saturday
afternoon, as the low pressure area slides east out to sea
toward Georges Bank by early Saturday evening. Will have slight
chance pops for some snow showers Saturday night into Sunday. A
ridge of high pressure will build into the region Sunday night
and Monday, with fair and dry weather expected.

Models showing some significant differences late Monday night
and Tuesday through Wednesday. GFS brings in a chance of rain or
snow on Tuesday and Wednesday, while The ECMWF model has
precipitation further south and mainly south of New England for
Tuesday and Wednesday. Thus, forecaster confidence is low for
the Tuesday and Wednesday forecast, given the model differences.
Thus, have stuck with superblend pops for Tuesday and Wednesday,
and will have a chance of rain and snow in the forecast at this
time.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
Through 18Z Thursday...Mainly VFR conditions expected through
the period as a ridge of high pressure builds slowly southeast
from Canada through the period. Expecting some areas of flurries
or light snow showers, with some areas of MVFR ceilings, mainly
between 18Z Wednesday through 04Z Thursday. Most of the flurries
or light snow showers will be confined to the Adirondacks and
the Green Mountains.

Outlook 18Z Thursday through Monday...

18Z Thursday through 12Z Friday...VFR under high pressure.

12Z Friday through 00Z Sunday...MVFR/IFR in periods of rain and
snow.

00Z Sunday through 00Z Monday...Areas of MVFR in scattered
light snow showers.

00Z Monday through 00Z Tuesday...Mainly VFR conditions expected
as a ridge of high pressure builds into the region.

&&

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

&&

$$
SYNOPSIS...Lahiff
NEAR TERM...Lahiff
SHORT TERM...JMG
LONG TERM...WGH
AVIATION...WGH



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