Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 251140

Area Forecast Discussion
National Weather Service Burlington VT
740 AM EDT Mon Sep 25 2017

After some early morning fog expect plenty of sunshine and highs
in the mid 80s to lower 90s. A shower or two may pop up along
the spine of the Green Mountains this afternoon. The above
normal temperatures will continue right through the middle of
the week as high pressure remains over the area. Expect dry
weather on Tuesday but as a trough of low pressure moves into
the region late Wednesday through Thursday morning the chances
for showers will increase...especially near the Canadian Border.


As of 740 AM EDT Monday...Going forecast in good shape and no
changes needed at this time. Little change in temperatures at
925/850 millibars from yesterday to today and thus see no reason
why we see high temperatures very similar to yesterday...mid
80s to lower 90s...which will break more records. Dew points
well into the 60s will push heat index values into the lower
90s. Should see plenty of sunshine once again as ridging aloft
exists. Hard to ignore the BTV4 showing on consecutive runs the
potential for some isolated convection over the Green Mountains
this afternoon. Plenty of instability and the mountains of
course are a natural source of lift. Cap overall should
hold...but cannot rule out a couple can break through the cap.
Flow aloft is weak so any showers would not be able to move off
the terrain...thus having little impact overall. Have included a
slight chance of showers for parts of the Green Mountains.

Any showers quickly come to an end tonight and high dew points
will keep overnight lows above normal and should see fog
developing with clear skies and light winds. On Tuesday once
again little change in 925/850 millibar temperatures and will
continue to go with more record breaking temperatures with highs
in the mid 80s to lower 90s. Will be interesting if here at BTV
we can actually hit three straight days of 90 degrees...something
that never occurred this summer.


As of 323 PM EDT Sunday...Its much of the same story for Tuesday
evening as the ridge will still be in place. High heat during
the day Tuesday and high dewpoints during the afternoon will
lead to fog overnight. General feeling is that there will be
some dense fog in the sheltered valley locations with some
patches of fog elsewhere. Overnight lows will be in the 60s
again, which is more indicative of our normals highs this time
of year.

The airmass will be slightly changing into Wednesday as the
ridge finally breaks down however not much changes in the thermal
profile until late. 925mb temps still support temps in the upper
80s with 90`s in the Valleys. I wasn`t as bullish on that as
we should start to build in some cloud cover that would
insulate the North Country from peak heating. Even so the
forecast of mid to upper 80s would still set or tie records at
BTV/MPV/MSS/1V4. With records possible I`ll hold on to the
previous discussion highlighting heat hazards below:

While these temps are considered sub advisory(<95 F), they are
not to be taken lightly especially given the time of year. Based
on the forecast and current records, its expected that records
will fall at all sites by 3-5 degrees. Prolonged exposure
outside combined with strenuous activity can lead to heat
related injuries. Please take caution, stay hydrated and take
frequent breaks during any outdoor activities. This will be the
fourth consecutive day with 90+ degree heat indexes during the


As of 323 PM EDT Sunday...Wednesday night is when we should
finally start to see some reprieve from the heat. A mid level
short wave will finally move into the North Country but the
moisture isn`t very strong. I`ve trended the forecast back
another 3-6 hours as guidance seemed overdone on the precip
threat during the late afternoon Wednesday.

A weak cold front will swing through during the overnight hours
Wednesday and bring scattered showers. Given the overnight
timing I dont feel there will be any thunder threat so I`ve
opted to continue with no mention of thunder. Behind the front
we get into cold air advection and see temps return to near
normal with highs in the 60s and lows in the 40s.

Late in the week heading into the weekend guidance is starting
to bring a shortwave trough into the region so I`ve mentioned
slight chance for pops but I dont have high confidence in
timing of the isolated to scattered showers.


Through 12Z Tuesday...Some fog will linger at most sites through
14z with a wide range of visibility categories...MVFR to VLIFR.
After 14z looking at VFR through about 06z before fog returns at
most sites for the remainder of the period. Little in the way of
cloud cover through the period but brief periods of LIFR to
VLIFR ceilings associated with the fog...especially at KSLK and
KMPV. Winds will be less than 10 knots through the period.


Monday Night: VFR. Patchy FG.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Chance SHRA.
Thursday: VFR. Slight Chance SHRA.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. Slight Chance SHRA.


Record high temperatures and year recorded for the period Sunday Sep 24
to Wednesday Sep 27

Day    Burlington    Massena      Montpelier
9/25   85 / 1891     90 / 2007    85 / 2007
9/26   84 / 1934     82 / 1970    83 / 2007
9/27   83 / 1920     82 / 2003    80 / 2007

For Burlington, here are the latest in the year dates for reaching
specific temperature thresholds

90F or higher:  9/16/1939
88F or higher:  9/22/1965
87F or higher:  9/23/1895
86F or higher:  9/23/1895 (was 87F that day)

Day   Burlington   Massena   Montpelier   St Johnsbury
9/23                 86
9/24     91          88         85          89* (Tied)




NEAR TERM...Evenson
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