Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 170547

Area Forecast Discussion
National Weather Service Burlington VT
147 AM EDT Thu Aug 17 2017

Dry weather is expected across the North Country through
Thursday night as high pressure builds over the northeast.
Temperatures will quickly return to seasonal normals Thursday
and Friday. A low pressure system approaching the area on Friday
will bring a return of showers and a few thunderstorms beginning
Friday afternoon.


As of 147 AM EDT Thursday...Overall going forecast in good
shape with quiet weather over the area. Seeing area of mid
clouds over southern Quebec Province moving southeast and this
should reach northeast Vermont and have added some clouds to the
forecast. Otherwise drier air mass and stronger flow just off
the surface should limit fog development with just some of the
favored locales seeing some fog toward sunrise. Rest of forecast
remains untouched.


As of 132 PM EDT Wednesday...High pressure remains over the
area on Thursday leaving a stellar day across the board with
temperatures returning to near normal with light winds.

Clouds advancing ahead of the next system moving into the Great
Lakes should hold off until Thursday night. Model consensus
continues to show precipitation holding off until Friday, and
most likely friday afternoon and evening. Have continued the
trend of keeping POPs restrained early Friday and ramping up
through the day with highest pops Friday evening. Model forecast
soundings show at least some modest elevated instability so
have some thunder chances included as well. The system will be
fairly progressive so lingering heavy rainfall potential appears
to be low despite PWATs increasing to between 1.5 and 2" as
indicated by the GFS. Overall a solid moderate rainfall event
for much of the region.


As of 340 PM EDT Wednesday...Overall not too much different
from the previous forecast based upon the 12z guidance suite --
perhaps the exception being a little later timing for the system
mid-week. Still looks like warmer than normal temperatures
through the period, especially as we get into Monday and
Tuesday. Didn`t stray far from the blend of guidance as the 12z
GFS and ECMWF weren`t too different than each other and the
previous 00z run. If you are curious for some additional details
in the forecast, just keep on reading...

Saturday: still have upper trough approaching the region during
the day, and along with a good amount of residual moisture, we
should see a few showers develop throughout the day. Instability
looks limited, especially across northern NY. GFS and NAM
indicate some CAPE across Vermont and point east, so have
painted in a slight chance of a thunderstorm for the afternoon
hours for the eastern half of the region. Not looking for
anything strong or any kind of heavy rain issues. Won`t be a
washout at all, but just one of those days where we can`t rule
out showers.

Sunday: Upper trough will be passing overhead during the day,
but not too much in the way of low level moisture or other
forcing. With the trough also comes some "cooler" air aloft
(about 11C at 850mb) and that will limit the overall instability
potential for the day. Thus looking for a good deal of sunshine
with highs pretty close to normal for this time of the year.
Definitely the better of the two weekend days.

Monday (Eclipse Day): Looks like Mother Nature will cooperate
for us, and allow us a good view (make sure you are wearing
proper eye protection!) of the partial eclipse in these parts.
High pressure at the surface, along with weak ridging aloft
should keep things dry for the vast majority of the area. 850mb
temperatures warm to about 15C, so we`ll see high temperatures
reaching the mid 80s for the lower elevations, and close to 80
in the higher terrain.

Tuesday: Ridging moves off to our east, allowing a southwest
flow to develop at the surface through mid-levels. A shortwave
will also be moving into the Great Lakes region by late in the
day. Previous model runs were a little faster with this
shortwave, and with the slower solutions, have backed off on the
chance for precipitation. Still, with height falls, an EML
layer, some shear aloft and decent surface instability/CAPE
thanks to temperatures well into the 80s, there are suggestions
we`ll have some convection around by the afternoon. Have painted
in roughly 30-40% chances. By the way, Tuesday should be the
hottest day of the stretch. GFS suggests 850mb temperatures up
to 17C or so, which support highs in the mid-upper 80s in the
valleys, if not making a run at 90F in a few places. This will
be dependent on cloud cover however, and if that upper trough
speeds up, there would be more showers and clouds around which
would keep us a bit cooler.

Tuesday Night/Wednesday: Confidence in the details are
admittedly not too high. Differences between 12z GFS and ECWMF
models are more significant with the timing of the shortwave
passage and it`s associated convection. Euro is quickest, with
everything pushing off to our east by Wednesday morning, while
the GFS has the trough coming through during the day Wednesday.
As mentioned earlier, this is also slower than prior model runs.
Given those differences, the forecast for Tuesday night and
Wednesday are more general in nature and subject to considerable
change before we get there. So have 45-60% PoPs for the entire
period based upon the model blends. Based on this timing, the
threat for strong/severe t-storms is lower, however if future
model runs change their timing such that the trough swings
through during the daytime heating, then the potential for
stronger storms increases. At this point, it`s more of a "wait
and see" situation.


Through 06Z Friday...VFR conditions expected for much of the
area and for much of the period as only expecting some mid and
high level clouds across the area...especially this afternoon
and tonight. There will be a small window of IFR conditions at
KSLK and KMPV between 09z and 12z due to low clouds and fog.
Winds will generally be under 10 knots through the period.


Friday: VFR/MVFR. Likely SHRA...Slight Chance TSRA.
Friday Night: VFR. Likely SHRA...Slight Chance TSRA.
Saturday: VFR. Chance SHRA...Slight Chance TSRA.
Saturday Night: VFR. Slight Chance SHRA.
Sunday: VFR. Slight Chance SHRA.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.




NEAR TERM...Banacos/Manning
SHORT TERM...Manning
LONG TERM...LaRocca/Nash
AVIATION...KGM is the U.S. government's official web portal to all federal, state and local government web resources and services.