Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 271825

Area Forecast Discussion
National Weather Service Burlington VT
225 PM EDT Tue Sep 27 2016

Nearly stationary upper level low pressure over Lake Superior will
continue to bring dry and seasonally warm conditions to the North
Country through Wednesday. Chances for showers increase for the
end of the work week and into the weekend though as the low drifts
southward into the Ohio River Valley on Thursday, remaining there
through Saturday.


As of 225 PM EDT Tuesday...It`s turned out to be yet another
gorgeous early fall day across the North Country as an occluded
front has shifted east of the region this morning leaving us
underneath a mid-level dry slot. Partly sunny skies have ruled,
along with temperatures climbing into the mid 60s to low 70s.
Dewpoints have lowered to very comfortable levels as well,
generally in the 40s. We have seen a few isolated showers though
move through the St. Lawrence and northern Champlain Valleys, but
that activity has since dissipated or is dissipating so a quiet
and comfortable afternoon will persist into this evening.

For tonight into Wednesday, a semi-stationary closed upper low
over Lake Superior will continue to be the dominating weather
feature across the Great Lakes and into the Northeast as it very
slowly meanders south. Mean south/southwesterly flow in a dry
slot aloft will continue to rule over the area which will keep
conditions dry with variable cloudiness. It will also keep us on
the mild side of normal in regards to temperatures with tonights
lows only dropping down into 40s for most, exception being the
colder hollows of the Adirondacks where some upper 30s are
possible. Highs tomorrow will be similar to today for locations
west of the Green Mountains in the mid 60s to low 70s, but east of
the spine it`ll be a little cooler as a low marine stratus layer
moves in overnight and continue through the first half of
Wednesday. If the stratus deck wasn`t there tonight, fog would be
a good bet for all of our climo favored river valleys, but as such
I think it will be confined to northern New York where skies will
be clearest and winds light.


As of 351 AM EDT Tuesday...Large scale pattern shows closed 5h/7h
circulation across the Ohio Valley with building ridge both aloft
and at the surface across eastern/southern Canada. This complex
and nearly stationary pattern will produce above normal
temperatures and several chances for precip. However...latest
trends show best potential of heavier rainfall staying closer to
the upper level circulation over the Ohio Valley and Mid Atlantic
States through Thursday. Have continued with a mainly dry forecast
for best energy and moisture is located over the Ohio
Valley. An isolated shower or sprinkle is possible over the
mountains and have mention slight chance pops to cover this
potential. Progged 850mb temps near 7c support highs well into the
60s with a few 70s possible...especially if we can see some sun in
the warmer valleys. By Thursday...have noted easterly 850mb flow
of 15 to 25 knots...may help to advect low level moisture into
central/eastern vt. Still plenty of uncertainty on depth of
moisture and high only mention chance pops across
southern/eastern VT on Thursday...with some areas of drizzle
possible in the mountains. Thinking additional clouds will keep
southeast cwa cooler with highs mainly in the 60s...but lower 70s
possible Saint Lawrence Valley...with lows mainly in the 50s.


As of 351 AM EDT Tuesday...Little change in the overall synoptic
pattern is expected through closed mid/upper level
low pressure continues to sit and spin across the Ohio Valley.
Eventually pattern will break down and cyclonic circulation will
weaken as it lifts across the NE CONUS by next weekend. Still
plenty of uncertainty on the overall impacts of system and
placement of best deep layer moisture and upper level support.
Latest trends show best moisture/lift remaining to our south
through Friday...with only weak embedded vorts lifting across our
cwa...resulting in chc pops. Furthermore....seems like moisture
fields and associated qpf weaken as it encounters dry air
associated with surface ridge. Guidance shows a tight north to
south precip gradient across central New England into the Mid
Atlantic...given this scenario have continuity to mention chc
pops during the Thurs Night into Saturday time period. Best chance
for measurable qpf will be along the se upslope regions of the
green mountains of central/southern vt during this time period.
Also...prevailing east to southeast flow may result in areas of
low clouds and drizzle...with cooler temps. Thinking highs will
generally range from the upper 50s/lower 60s mountains of eastern
VT to lower 70s Saint Lawrence Valley with near 70f for the
Champlain Valley. Have kept temps several degrees above superblend
because of clouds...with lows mainly in the 50s...which is above
10 degrees above normal.


.AVIATION /18Z Tuesday THROUGH Sunday/...
Through 18Z Wednesday...Mainly VFR conditions are expected through
the period with a few tricky exceptions. Scattered VFR clouds
across the area this afternoon will generally dissipate going into
the evening hours, but overnight MVFR and VLIFR are likely at KMPV
and KSLK. For KMPV, a developing marine stratus layer off the
Maine coast will make a run into portions of eastern Vermont
towards dawn Wednesday, mainly affecting terminals east of the
Greens. Meanwhile at KSLK, clearer skies, light winds and recent
rainfall will make for the high likelihood of dense fog as early
as 03z, and lasting through at least 12z. After 12z, KSLK fog
burns off, but timing of the stratus deck lifting at KMPV is a bit
more uncertain. Have gone with 16z there, but could see it
lasting longer. Final aviation challenge will be increasing
southeasterly flow at KRUT, where expect gusts 20-25kts to begin
early Wednesday morning and likely last through the day.

Outlook 18z Wednesday through Sunday...

18z Wed - 00z Fri: Mainly VFR.

00z Thu - 00z Mon: Mainly VFR with MVFR in rain showers possible,
especially on Saturday/Sunday.




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