Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1034 PM EDT sun Sep 25 2016
tranquil early Fall weather will persist through Monday, as a
large area of Canadian high pressure crosses the region. The crisp
air mass will allow areas frost to develop once again tonight,
with lows generally ranging through the 30s. Developing southerly
winds will allow for moderating temperatures on Monday, with high
temperatures reaching the mid to upper 60s in most valley
locations. A frontal system approaching from the west will bring
our next rainfall event Monday night into Tuesday.
Near term /until 6 PM Monday evening/...
as of 1032 PM EDT Sunday...for tonight, surface high pressure
extending from wrn Quebec southward into central New York/PA will drift
very slowly ewd. Skies are generally clear at 02z, and will see
just a few cirrus from time to time drifting ewd from the ern
Great Lakes, per infrared imagery. With little airmass change from last
night and winds aloft lighter, we should see even better radiative
cooling conditions than this morning. Despite 925-850mb temps
warmer than last night, surface temps area-wide should be a few
degrees cooler producing more areal coverage of frost. Have
maintained frost advisories and freeze warnings for just about all
of the btv cwa, excluding Grand Isle County where warmer Lake
Champlain waters should keep temps in the upper 30s to low 40s.
Elsewhere, lows will widely ranging through the 30s, with some
upper 20s possible in the Northeast Kingdom and locally low/mid
20s in the colder hollows of the northern Adirondacks (i.E. Kslk).
In addition, unlike last night where winds aloft mitigated fog
development, expect to see some patchy dense fog develop in the
usual climo favored river valleys after midnight.
On Monday, the aforementioned high shifts off the New England
coast allowing winds to shift to the south and temperatures to
warm to more seasonal values in the mid to upper 60s. We'll start
the Monday under full sunshine with any morning fog burning off,
but as we progress into the afternoon we anticipate some
increasing mid and upper level clouds from west as a large closed
low approaches. Any rain showers associated with this system
should hold off until Monday night though.
Short term /6 PM Monday evening through Tuesday night/...
as of 430 PM EDT Sunday...models continue to be consistent with
large 500mb trough associated with surface closed low pressure
system over southwestern Ontario with a frontal boundary extending
southward across the eastern Great Lakes moving eastward. This
system will bring a strong 850mb jet of 35-45kts across the region
from west to east Monday night and pwats greater than 1 inch.
Latest NAM and GFS Show Low level deformation with the front
weakening as it moves across the north country Tuesday morning.
Therefore expect best chances for rain showers across northern New
York and especially in SW facing slopes as the low level jet will
lead to shadowing affects on leeward facing slopes and valleys.
On Tuesday, bulk of precip will affect the Green Mountains and
Northeast Kingdom but with SW flow continuing and the cold front
bringing cooler air over Lake Ontario, the St Lawrence Valley
could see some lake effect rain showers. Expect precip to end
Tuesday night as the frontal system moves into the Atlantic, while
the 500mb low retrogrades towards Chicago.
Long term /Wednesday through Sunday/...
as of 430 PM EDT Sunday...with 500mb low becoming cutoff, there
could still be slight to low chances for rain showers throughout
the period as models have difficulty determining movement of the
low. It does appear that bulk of energy will be south and west
with light northeast flow persisting over the north country. This
will keep clouds around with temperatures during the day reaching
the 60s and and at night generally in the 40s throughout the long
Aviation /03z Monday through Friday/...
through 00z Tuesday...mainly VFR conditions are once again
expected throughout the period, with the typical exception being
the high likelihood of vlifr in fog/fzfg at kslk/kmpv from 05-13z.
Light and variable winds overnight will pick up from the south-
southwest at 10-20 knots at all stations except rut which will
remain at 05-08 knots.
Outlook 00z Tuesday through Friday...
00z Tue - 00z Wed: VFR trending to a mix of VFR/MVFR in scattered
00z Wed - 00z Sat: mainly VFR with isolated MVFR cigs.
Vermont...freeze warning until 8 am EDT Monday for vtz003-004-007-008-
Frost advisory until 8 am EDT Monday for vtz002-005-006-009-
New York...freeze warning until 8 am EDT Monday for nyz026-027-029>031-
Frost advisory until 8 am EDT Monday for nyz028-035-087.