Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 261753

Area Forecast Discussion
National Weather Service Burlington VT
153 PM EDT Tue Jul 26 2016

High pressure slowly builds into the region today and Wednesday.
Dry weather is expected along with a warming trend as temperatures
by Wednesday will be well into the 80s with a few lower 90s
expected. The pattern will change later Wednesday night through
Friday as a broad trough of low pressure moves into the region and
enhances the potential for precipitation. High temperatures will
be at or slightly above normal on Thursday and Friday.


As of 153 PM EDT Tuesday...Steep low level lapse rates combined
with low level moisture will keep cumulus clouds around for the
rest of today into the evening hours. Cannot rule out an isolated
light rain shower this afternoon. NW winds 5-10 kts, occasionally
gusting 15-20 kts, continue on the northeast side of building low
level/surface ridge. Temperatures will continue to rise into the
upper 70s-mid 80s with a few spots reaching the upper 80s.

Tonight: High pressure continues to build into the region for a
continuation of dry weather. Any shallow cumulus over the higher
terrain will dissipate around sunset and clear skies/light winds
will take over. This could lead to some fog in the favored
locations. Low temperatures will range from the mid 50s to mid


As of 331 AM EDT Tuesday...00z guidance suite did not indicate
the need to make any substantial modifications to the forecasts
we`ve been offering for the last couple of days. So with that, a
few thoughts on each day

Wednesday: all guidance indicates 925mb temperatures will be
about 23C (give or take a degree) as the westerly flow aloft will
advect in a little piece of the heat that is solidly in place to
our west and south. given plenty of sunshine and expected deep
mixing to about 6000ft (800mb), we`ll end up with a deep dry
adiabatic lapse rate and even super-adiabatic near the surface.
what does this mean? well, a hot day. 23C at 925mb supports
temperatures topping out into the lower 90s in the valleys. Well
into the 80s elsewhere. Followed the previous forecaster and
painted in temperatures that were closer to the warmest guidance.
There will be a weak cold front north of the border during the day
that will likely spark some t-storms across Quebec. By very late
in the afternoon/early evening, that front will have sagged south
enough that we may have and isolated shower/t-storm working their
way through US Customs and Border Protection. Thinking any
isolated convection would probably be getting into far northern NY
and Vermont just before sunset. Minimal instability, so not
looking for anything strong. Given the warm airmass, we will
continue to have minor amounts of instability much of the night.
Add in a little bit of low-level forcing with that weak front, and
isolated shower or t-storm Wednesday night for northern sections
seems reasonable. Temperatures will only drop to the mid-upper 60s
for most areas.

Thursday: Weak front continues to slowly move south, and will act
as a focus for scattered showers and a few t-storms. Models show
precipitable water values rising above 1.5" as the moisture pools
along the front, so could be an isolated heavy downpour. More in
the way of clouds and a bit cooler temperatures aloft will result
in temperatures about 5 to 7 degrees cooler than Wednesday. Still
above normal however. Ranging from lower 80s across the north to
perhaps around 90 down in the Connecticut River valley around
Springfield VT. Kept PoPs in the 35-45% range at this point. Later
forecasts may show an increase. At this point not expecting any
strong storms as guidance doesn`t show over the top instability or
dynamics. Probably more just "garden variety" type stuff. Thursday
night the bulk of the showers will push south of the region --
perhaps still hanging on around Rutland. Overnight lows will range
from the upper 50s to lower 60s. Might be still a bit muggy down


As of 331 AM EDT Tuesday...00z GFS and ECMWF continue to be
similar to their own previous runs, and have diverging solutions
between one another. So confidence is not all that high,
especially for the weekend and early next week. At least there
does not appear to be any high impact/significant weather on the

Friday: Weak/diffuse front will be somewhere to the south, but
close enough that southern sections will see more clouds and a
chance for a shower or isolated t-storm. Could end up being a
sunny/dry day closer to the Canadian border. GFS and ECMWF are in
decent agreement, though GFS has a low pressure moving south of
New England during the day. Not really a player in our weather.
Temperatures should be close to normal (upper 70s to lower 80s).

Saturday/Sunday: Model differences more significant. GFS takes
it`s surface low off the coast, and we have a light northerly flow
develop which cools us down and dries us out. At face value, GFS
says below normal temperatures with highs only in the 70s on
Saturday, and back to near normal Sunday with plenty of sun. ECMWF
keeps the diffuse front stationary to our south thru the weekend,
and has a couple of weak lows move along that front. It paints a
generally mostly cloudy weekend with scattered showers both days.
Given this continued uncertainty, the best course of action
remains sticking to a blend. Thus 20-35% PoPs for both days
(lowest north, highest south).

Monday: both models indicate a shower is not out of the question,
but how they get to their solution is different. GFS in the
process of bringing back warmer air and more moisture, while ECMWF
shows a shortwave zipping out of the region during the afternoon
with slightly cooler temperatures coming in. We`ll know exactly
how things will turn out on Tuesday of next week. For the time
being, the forecast will feature a blend of the previous 12z data
plus the latest 00z output from the GFS and ECMWF.


.AVIATION /18Z Tuesday THROUGH Sunday/...
Through 18z Wednesday...VFR conditions with sct-bkn cumulus
clouds will persist through this evening. IFR/LIFR fog development
possible at KSLK and KMPV mainly between 07z-12z Wednesday morning
as winds decouple and skies clear.

After sunrise, fog will begin to erode and VFR conditions
expected at all TAF sites with mainly clear skies and southerly
winds of 5-10 kts. High and mid level clouds will encroach upon
the North Country from the Northwest late in the period.

Outlook 18z Wednesday through Sunday...

18z Wed - 00z Thu: Mainly VFR under high pressure.

00z Thu - 00z Fri: VFR with MVFR/IFR possible in isolated to
scattered showers and thunderstorms

00z Fri - 12z Sun: Generally VFR, chance for MVFR in showers
in the afternoon Friday and Saturday.

12z Sun onward: Chance for widespread showers.




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