Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 200018

Area Forecast Discussion
National Weather Service Burlington VT
818 PM EDT Wed Jul 19 2017

High pressure gives way to a weak cold front moving in this
afternoon into northern New York and into Vermont this evening
bringing with it with isolated showers and thunderstorms.
Another weak frontal system will bring another chance of showers
and thunderstorms Thursday into Friday. This weekend will see
weather become a bit cooler for Saturday into the first part of
Sunday under high pressure. Sunday into Monday brings the next
chance of showers and thunderstorms.


As of 803 PM EDT Wednesday...Isolated showers continue to ride
along the international border this evening, but dry air is
mostly keeping the storms out of our forecast area. Still have
chance of showers across our most Northern zones and slight
chance of thunder. Temperatures are still pretty warm across the
area, mid to upper 70s. Previous discussion follows.

Weak cold front pushes through northern New York bringing some
late afternoon instability increases with 500-1250 J/kg and
0-6km shear around 25-30 knots. Mid and high level cloud cover
is increasing as the front pushes in which should limit any
significant potential convection. Coupled with that, low level
moisture and dynamics are limited but a few showers and possible
thunderstorms through the later afternoon and evening hours are
possible, but the best chances, after 22Z will see daytime
heating on the decline so activity should be isolated at best.
Overnight skies will clear a bit and patchy fog mainly in the
river valleys is possible again though as the low level flow
turns NW and we get some weak cold advection in the low levels
the coverage is pretty uncertain.

Thursday will be mainly dry though another approaching upper
level trough will bring more clouds and a chance for a few
showers or thunderstorms later in the day with warm advection
returning. Some very limited instability is forecast with CAPE
500-1500 J/kg but the coverage is very spotty and the PoPs are
rather low so again not . The best instability is forecast
continues to remain well south and west of our area. Flow shifts
west to northwest aloft becomes established over the area
Thursday night. Showers activity, what little of it there is,
should come to an end after midnight.

Temperatures overnight will be in the mid to upper 60s with
highs tomorrow a little bit cooler in the lower to mid 80s.


As of 229 PM EDT Wednesday...High pressure will be building
into the region as west to northwest flow develops aloft. Drying
air should lead to some breaks in the clouds during the day
which will lead to temps warming into the mid 80s for the valley
locations and around 80 in the Northeast Kingdom and
Adirondacks. With dry air all around I anticipate mostly quiet
weather so I`ve opted to drop even the slight chance wording.
Its possible we could see a stray mountain shower but nothing of
any impact. In the evening hours we should still be under warm
air advection and so our evening lows will continue to be
slightly above normal with temps falling to the mid to low 60s.

Saturday looks to be a wonderful summer North Country day as
high pressure crests just to our northwest. We should see some
scattered cloud cover but the sensible weather will be quiet.
The cloud cover should be enough to keep temps just on the
cooler side with highs in the 70s to near 80.


As of 229 PM EDT Wednesday...As we end the weekend the flow
aloft will transition from northwesterly to more southerly ahead
of an advancing low pressure system. We will see clouds
increase as a surface boundary with that low pressure system
lifts to the north. Moisture advection increases quickly and the
chance for showers increase Sunday into Monday. PWATs increase
to 1.5 to 1.6 inches but not enough to be overly concerned.
Showers will move through with the best chance on Monday
morning. The best forcing is to our south but there are enough
dynamics to support the idea of a rumble of thunder Sunday night
through Monday morning.

The upper level trough will swing through late Monday into
Tuesday and so chances for shower will continue until the
surface front clears the North Country Tuesday afternoon. With
the persistent cloud cover and continued chances for rain, our
day time temps will be slightly below normal through the early
portion of the workweek while our overnight lows should be
around normal.


Through 00Z Friday...Aviation concern early this evening is
potential thunderstorm at mss...followed by fog/br threat aft
06z. Current radar shows developing showers with embedded
thunder along the international border with kmss reporting
lightning distant nw at this time. Have tempo a 1 hour tsra with
vis 4sm at kmss btwn 01-02z. Noticing lots of mid/upper level
clouds on vis satl pic...which combined with temps slowly
falling will delay fog/br development. Cross over temps are just
touched tonight...unlike last night when temps dropped 4 to 6
degrees below values...this leads to less confidence in fog and
associated ifr/lifr conditions. Have mention tempo with ifr
conditions at mpv/slk btwn 08-11z...with mvfr in br at kmss.
Light trrn driven winds overnight become southwest and
eventually northwest on vfr conditions prevail.

Thursday Night: VFR. Slight Chance SHRA...Slight Chance TSRA.
Friday thru Sat Night: VFR. NO SIG WX.
Sunday: VFR. Chance SHRA.
Sunday Night thru Monday: VFR/MVFR. Chance SHRA...Slight Chance




NEAR TERM...Neiles/Verasamy
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