Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 250548

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

Unseasonably strong high pressure will continue to bring fair
weather and warm, record high temperatures to the region through
Wednesday. By later Wednesday into Wednesday night the chances
of showers increase as a cold front crosses the area. Behind
this front temperatures will cool back toward more typical early
autumn values from Thursday onward into next weekend.


As of 148 AM EDT Monday...Overall forecast in good shape with
fog continuing to develop. Have indicated patchy fog everywhere
with patchy dense fog in the favored locations. Otherwise
everything else is in good shape.

Previous Discussion...
A very warm and muggy evening continues across the North County
with temps in the 70s to lower 80s and dewpoints mid 60s to
lower 70s. Current dewpoint at kmss is 73f and btv is
low level moisture is pooling with calm conditions associated
with large dome of high pres at all levels. Have bumped sfc
dewpoints up 2 to 4 degrees across the region...based on obs
along with hourly surface temps to match current values.
Otherwise...did tweak our overnight low temps here up several
degrees due to the urban heat island effect. Thinking lows range
from near 60f mountain valleys to around 70f locally here in
the CPV. Some patchy fog is possible in deeper valleys...similar
to last night. All covered well.

Previous discussion below:
High temperature records already falling in earnest as of 200
pm as deep layer, anomalously strong high pressure continues to
build across the northeast. This high will remain anchored in
place over the next 48 hours with more rinse and repeat weather
and record high temperatures on Monday in the 80s to near 90.
See climate section at bottom for specific records over the next
few days. Again, I leaned close to a multi-model bias-
corrected blend for max/min temperatures given little change in
airmass. This supports a somewhat wider than normal diurnal
range with typical late night/early morning mist/fog in favored
locales morning. Some suggestions that even the St. Lawrence
Valley may get in on the fog tonight per most recent NAM 3km


As of 323 PM EDT Sunday...The previous forecast remains on
track for Tuesday into Tuesday night. Models are in fairly good
agreement. The upper level ridge will remain over the region.
With no change in airmass, will hold onto max temps in the
upper 80s to around 90 degrees. This also pushes heat index
values once again into the 90-94 degree range.

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 third consecutive day with 90+ degree heat indexes
during the afternoon. With upper 80`s to low 90`s temps, the
overnight lows wont fall that much. Expect lows each night in
the upper 50s to low 60s which is 15-20 degrees above normal
for this time of year.


As of 323 PM EDT Sunday...Model solutions begin to diverge with
the handling of timing, and  to some extent placement, of the
mid level shortwaves and attendant cold front. Still looks like
the upper level ridge begins to break down heading into
Wednesday as a low pressure system begins to finally track
towards the North Country from the Great Lakes. With the flow
aloft not turning zonal until mid day Wednesday anticipate the
frontal system moving through slower than the models suggest.
I`ve removed pops Wednesday morning. Will still carry chance
pops Wednesday afternoon but have removed mention of thunder.
Any afternoon activity is expected to be pre-frontal and on the
weaker side with the cold front not expected to move through
until Wednesday night.

A trailing shortwave will move across the region the end of the
week. For now have gone with slight-low chance pops Friday into
Saturday due to timing uncertainties. The cold front will usher
in much cooler and more seasonal temperatures for the end of
the work week through the weekend.


Through 06Z Tuesday...Expect patchy fog to develop at most
locations early this morning with at least MVFR visibilities...
but KSLK...KMPV...KPBG...and KMSS will see IFR to VLIFR
conditions through about 14z due to low clouds and fog. After
14z all areas will be VFR with little in the way of cloud cover.
Winds will be under 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
9/24   84 / 1961     87 / 2010    83 / 1961
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)




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