Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 281938
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
338 PM EDT Sun Aug 28 2016

.SYNOPSIS...
The threat for showers and thunderstorms will increase across the
area this afternoon and evening as an upper level trough of low
pressure approaches from the west. Areas most likely to see the
showers and storms will be across the northern Adirondacks of New
York and the northern and central sections of Vermont. High
temperatures will remain above normal today. Some showers will
linger over the area Monday morning...but high pressure builds in
and brings drier air and seasonable temperatures.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 217 PM EDT Sunday...Current forecast in good shape.
Composite radar loop showing some scattered rain showers
developing over northern New York, mainly Clinton County at this
time.

Previous discussion from 652 AM EDT Sunday...Mid level moisture
continues to move across northern New York and the northern half
of Vermont this morning. There have been reports of sprinkles with
these clouds and have added to the forecast for the next couple of
hours. Otherwise...feel cloud cover will thin out mid-morning and
allow temperatures to warm and eventually reach the upper 70s to
mid 80s. This combined with dew points rising into the 60 to 65
degree range should help to create sufficient instability to
enhance the convective potential. As usual the models are too high
on the dew points and thus creating too much instability. Upper
trough over the Great Lakes region will lift northeast today and
thus dynamic support will be increasing over the area this
afternoon. As trough approaches...deep layer shear will be
increasing but will not be too strong. Feel enough ingredients
exist for thunderstorms to develop this afternoon and
evening...but none of them are strong enough to suggest storms
become severe. Cannot rule out a strong storm or two however with
gusty winds and heavy downpours being the main threats. Best
potential for thunderstorms looks to be across the northern
Adirondacks and the northern and central sections of Vermont.

For tonight...areal coverage of showers and storms will be
greatest during the evening hours...then quickly taper off after
midnight as instability and forcing diminish. Lows will generally
be in the 60s as plenty of low level moisture lingers over the
region.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 335 PM EDT Sunday...Surface front will be along the New
England coast Monday evening at the start of the short term
period, with 500 mb shortwave trough exiting the coast. Surface
high pressure and shortwave 500 mb ridging over the forecast area
Monday night with dry air. Surface dewpoints fall into the 50s and
1000-500mb mean rh drops below 30 percent. With clear skies and
light winds, good radiational cooling scenario, and lows Monday
night in the mid/upper 40s in the Adirondacks and Northeast
Kingdom, and 50s elsewhere. Will put in some patchy valley fog for
the usual places Monday night as well for potential of radiational
fog development.

Southerly flow returns quickly Tuesday when high pressure shifts
east of the area, and winds back in advance of next approaching
trough. Dry air also shifts east, and precipitable water increases
tuesday to around 1 1/4 inch, a little above normal. A weak
surface trough will move out ahead of an approaching 500 mb
shortwave trough and provide a focus for showers mainly in the
north Tuesday night. Temps Tuesday in the lower 80s except upper
70s in the Northeast Kingdom of VT and Adirondacks, supported by
850mb temps around 13c. Warmer temps Tuesday night than Monday
night with warmer southerly flow, cloud cover and higher dewpoints
all to limit radiational cooling.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 335 PM EDT Sunday...Wednesday is a transition day with
ridge over the western US and flat trough in the east. 500 mb low
moving through eastern Canada in northwest flow around the western
ridge. Surface trough pushes on through the area Wednesday and is
focus for afternoon convection, with upper trough lagging by 12
hours or so. Small amount of instability with capes near 500 j/kg.
At this point will continue with just showers and no mention of
thunder. Best chances for rain will be during the day Wednesday,
and lingering Wednesday night over higher terrain in areas favored
by upslope west to northwest low level flow.

Cold front arrives Wednesday night, and upper trough carves out
lower heights. Noticeably cooler and drier Thursday thru Saturday
with nil rain chances for the remainder of the forecast period.
850mb temps near 5-6C supporting max surface temps in the 60s to
around 70 depending on elevation. This will be a few degrees below
their climatological normals for this time of year.

Temperatures rebound late in the weekend with surface high
shifting east for warmer southerly flow on Sunday. Building ridge
in the east raises heights Saturday and Sunday, and 850 mb temps
back to 12-14C, with max surface temps those days in the low 80s.
Will see wide swings in temperatures the last half of the forecast
period with clear skies and warm sunny days, and also clear skies
and light winds at night conducive to good radiational cooling.

Initially lows will be in the 40s and 50s Wednesday night, with a
cooling trend for the remainder of the week. By Saturday morning
patchy frost is possible at Saranac Lake and across the deeper
valleys of the northeast kingdom. For Friday night/Saturday
morning lows will range from the low to mid 30s to upper
40s...except mid 50s near lake champlain. Average 1st frost at SLK
is Sept 7th...so pretty close to normal.

&&

.AVIATION /20Z Sunday THROUGH Friday/...
Through 18Z Monday...Expecting showers and thunderstorms to
develop across the region this afternoon into early this evening.
Mainly VFR conditions expected with some areas of MVFR/IFR in
showers and thunderstorms til 03Z Sunday. Some areas of IFR/MVFR in
fog from mainly 05Z til 12Z Monday, especially in sheltered valley
locations that receive rainfall this afternoon and this evening.

Outlook 18Z Monday through Friday...

18Z Monday through Thursday...mainly VFR through 18Z Wednesday, as
a ridge of high pressure builds into the region. Some areas of
MVFR in scattered rain showers 18Z Wednesday through 00Z Thursday,
as a cold front moves through the region.

Mainly VFR Thursday and Friday, as a ridge of high pressure builds
slowly southeast from Canada.

&&

.MARINE...
Winds will continue to increase out of the south today and reach
the 15 to 25 knot range this afternoon and evening. Thus a lake
wind advisory is in effect for this time period due to the
stronger winds and choppy waters. In addition...the potential for
thunderstorms will exist this afternoon and evening which will
have the potential to produce gusty winds and heavy downpours.

&&

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

&&

$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/WGH
SHORT TERM...Hanson
LONG TERM...Hanson
AVIATION...WGH
MARINE...Evenson


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