Area Forecast Discussion
Issued by NWS Burlington, VT
FXUS61 KBTV 292350
Area Forecast Discussion
National Weather Service Burlington VT
650 PM EST Tue Nov 29 2016
An initial wave of low pressure will exit to our north and east
this evening, allowing steady precipitation to end from west to
east early tonight. Skies will remain cloudy with patchy
drizzle and fog developing overnight. Another wave of low
pressure and associated warm front will bring additional
moderate rainfall to the North Country Wednesday afternoon
through Wednesday night, along with locally gusty south to
southeast winds. Rainfall amounts between a half and three-
quarters of an inch are generally expected. A large upper trough
will then persist across New York and New England, providing
mostly cloudy skies and chances for rain showers Thursday and
Friday, and scattered snow showers for the weekend.
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 629 PM EST Tuesday...Current radar shows light rain across
our Eastern Vermont zones and temperatures above freezing
across the entire area. Showers will continue for the next few
hours, especially across Southeastern Vermont. Otherwise mainly
just cloudy with light winds across the North Country. Some fog
development is expected after recent rainfall and with small
dewpoint depressions and light winds. Previous discussion
Generally looking for -RA to end across central/Eastern VT
01-03Z. Once this happens, sea-level pressure field becomes
nearly flat across our region, and weak flow regime with
saturated conditions will prevail thru the remainder of the
overnight hrs into Wed morning. Looking at continued low stratus
deck, with some patchy drizzle and fog expected...right thru
14-15Z Wednesday with little flow to mix out near surface
inversion layer. Temps quasi-steady tonight, mainly holding in
the upper 30s to lower 40s. Meanwhile...developing surface low
across the upper Ohio Valley and ewd extending, strong warm
front will be lifting Northward across PA at 15Z Wed, with the
warm front reaching central NY and Western MA by 21Z Wed.
Strong low- level WAA and isentropic ascent will overspread the
North Country from south to north Wednesday afternoon into
Wednesday evening, with surface low tracking to our west into
southeastern Ontario during Wednesday night. PoPs near 100%
Wednesday evening with periods of moderate rain expected. Total
rainfall by 12Z Thursday generally 0.50-0.75", but 900-800mb SE
flow increasing to 50-60kts will allow for some orographic
enhancement on the Eastern slopes of the Greens, where
localized 1" amts are expected. Mild temps on Wednesday...with
highs mainly mid-upper 40s, and lower 40s for Wednesday night.
Only other issue will be possible period of gusty winds, as SE
925mb flow increases to 40-45kts around 00-03Z Thu, per 12Z NAM,
just in advance of the warm front. Anticipate steady rainfall
during this time frame, which tends to lead to stable PBL
conditions mitigating downward mixing and momentum transfer. Did
include some SE winds 20-25mph with gusts to 35mph on the
immediate Western slopes of the Green Mountains with possible
downslope effects. Otherwise, higher gusts should be confined to
the exposed higher terrain areas of the Green Mountains into
the nrn Adirondacks, peaking during Wednesday evening. As
surface low moves past, will see a band of strong SWLY 925mb
winds of 45-50kts moving across the St. Lawrence Valley. This
may also cause some gusty winds to 35-40mph around KMSS and the
surrounding St. Lawrence Valley toward daybreak on Thursday.
Will continue to monitor.
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 355 PM EST Tuesday...Precipitation to wind down Thursday
morning as secondary low pressure area moves into the Gulf of
Maine, with more showery precipitation expected Thursday
afternoon across the region. The region will remain under the
influence of a closed upper low over Canada, which will bring a
chance of rain or snow showers to the region Thursday night.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 355 PM EST Tuesday...The region will remain under the
influence of an upper low over Canada, so have kept in chances
for rain and snow showers from Friday through Saturday. Models
showing upper ridge to build into the region Sunday through
early Tuesday. Have gone with a dry forecast for Sunday and
Sunday night. For Monday, models suggesting mainly dry
conditions for Monday and Monday night, as both the GFS and
ECMWF show an upper ridge building into the region. Have lowered
superblend pops for Monday and Monday night to mesh with
neighboring offices, but expecting mainly dry conditions for
Monday and Monday night. Models showing timing differences for
Tuesday, with the GFS model bringing in precipitation Tuesday
afternoon, while the ECMWF model holds off precipitation until
Tuesday night. Have opted to hold off precipitation until
Tuesday afternoon. Forecaster confidence for Tuesday is low,
given model timing differences.
.AVIATION /00Z Wednesday THROUGH Sunday/...
Through 00Z Thursday...A mix of mvfr, ifr, and lifr conditions
prevail across our taf sites this evening. The highest
potential for prolonged period of ifr/lifr conditions with cigs
below 400 feet and vis < 1sm will occur at slk/mss tonight.
Meanwhile...thinking ifr cigs develops at mpv/rut/btv
associated with low clouds and areas of drizzle and fog by 06z.
Fog and mist will continue across the mountains...causing the
terrain to be obscured. Radar shows areas of light rain may
still impact rut/mpv through 03z...before shifting to our east.
Difficult to determine when cigs/vis improve on Weds...ahead of
our next weather system which arrives on Weds afternoon.
Thinking mvfr with some vfr conditions develop by
16z...especially btv/pbg/rut...before rain arrives after
18z...with mvfr/ifr redeveloping by evening. Light terrain
driven winds tonight will become southeast on Weds...with a few
localized gusts to 25 knots at rutland after 18z.
Outlook 00z Thursday through Sunday...
Widespread rain with embedded periods of moderate rain will
impact our taf sites through 12z Thursday...with mvfr cigs/vis
and occasional ifr conditions likely. Gusty southeast winds are
possible along the western slopes...and will impact rutland with
gusts up to 30 knots possible. Winds shift to the west/southwest
by Thursday morning with some localized gusts up to 30 knots
possible at slk/mss. These strong wind profiles and changing
winds with height will cause areas of low level turbulence and
shear. A slow clearing trend is anticipated with ifr conditions
becoming mvfr on Thursday into Friday. Mainly mvfr will prevail
in the mountain taf sites and a mix of mvfr/vfr in the valleys
through the upcoming weekend.