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000
FXUS61 KBTV 241951
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
351 PM EDT Mon Sep 24 2018

.SYNOPSIS...
Another quiet night is expected across the North Country before a
warm front moves through the region on Tuesday. Strong and gusty
southerly winds will accompany period of moderate to heavy rainfall
Tuesday morning and Tuesday afternoon. Winds will diminish Tuesday
night but pick back up again on Wednesday ahead of a cold front that
will push through the region during the afternoon and evening hours.
Some strong thunderstorms are possible with the cold front with a
slight chance of a severe thunderstorm or two. Following the cold
front, quieter and drier weather is expected through Saturday before
the next system approaches from the west.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 301 PM EDT Monday...The quiet before the storm is being observed
across the North Country this afternoon with most places seeing
a beautiful fall day. Satellite data continues to show a pocket
of stratus entrenched across eastern Vermont as a marine air
mass has banked up along the Green Mountains. Froude numbers are
nearly zero this afternoon which suggests that flow is
subcritical and blocked. A stable air mass caps the atmosphere
above this stratus deck which has made it very difficult to mix
out the cloud deck but latest imagery is showing clouds eroding
from the east. This trend will continue into the overnight hours
which will help break up the clouds but several places over
eastern Vermont may miss out on sunlight this afternoon.

Heading into tonight, clear skies will be seen through midnight
before cloud cover begins to increase from the southwest. An
approaching warm front will also allow for rain chances to increase
after midnight although steady rainfall isn`t expected until the
early morning hours on Tuesday. By 8 AM Tuesday, rain will have
already tracked across northern New York and made it into central
Vermont. Like the event a few days ago, it looks like a large
portion of the area will see around a half of an inch of rainfall as
the warm front lifts through the region. There are a few signs of
potential upslope/downslope components as Froude numbers remain below
0.5 through the frontal passage but frontogenesis in the low and mid
levels may be enough to overcome this blocked flow. Should the
blocked flow develop, higher rainfall amounts will be possible on
the western slopes of the Adirondack Mountains. The current forecast
reflects a solution where the upper level support in the low to mid
levels will be enough to overcome the strengthening southwesterly
LLJ with pretty uniform rainfall amounts seen across the North
Country.

While the warm front approaches the region, high pressure situated
over New England will shift eastward over the Atlantic Ocean. As
this happens, the pressure gradient over the North Country will
compact and gusty winds will begin to develop toward sunrise on
Tuesday. Southerly winds in the 10 to 20 mph with gusts to 35 look
pretty common through the afternoon on Tuesday before the boundary
layer decouples and lighter winds will be observed. Tuesday night
will end up being a pretty warm and muggy night as temperatures warm
through the night as both 925 mb and 850 mb quickly warm behind the
warm frontal passage earlier in the day. The highs on Tuesday will
likely end up being the low for Wednesday with temperatures warming
overnight.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
As of 334 PM EDT Monday...Active weather day expected Wednesday,
with possible tstms with gusty and locally damaging winds
possible.

Will see moderately strong S-SW gradient flow in place during
the day Wednesday, in advance of strong cold front approaching
from sern Ontario. Anticipate south winds 15-25 mph - with gusts
up to 35 mph - especially with channeled flow in the Champlain
Valley. Anticipate mostly cloudy conditions, but dewpoints will
climb into the mid- 60s with continued south winds and moisture
advection in advance of the cold front. Deep-layer wind fields
also become moderately strong in advance of the bndry, with sfc-
6km bulk shear values of 45-55kt. As is typical with a fall
system, some question as to overall convective instability, as
lapse rates will be nearly moist adiabatic and insolation should
be limited. That said, rich PBL moisture may contribute to
narrow axis of SBCAPE 500-1000 J/kg that could drive tstm
potential with strong large-scale forcing along the frontal
bndry. Anticipate a narrow band of showers, with potential for
embedded tstms. If storms can become linearly organized, could
see a damaging wind threat during the late aftn/evening hours
across nrn NY and thru the wrn half of VT. In agreement with SPC
slight risk on day 3 for potential wind damage threat. Will
continue to monitor this potential.

Otherwise, will see band of moderate rainfall along the cold
front along with a westerly wind shift and low-level CAA heading
thru Wednesday night. Looking for daytime highs on Wednesday in
the 74-78F range, followed by lows Wednesday night mainly in the
40s, except locally in the lower 50s near Lake Champlain and
across the upper CT river valley. Additional rainfall amts
Wednesday generally 0.3-0.6", but may be locally higher with any
convective storms.

Thursday will feature much quieter wx as ridge of high pressure
builds into the nern CONUS, with light wind conditions.
Increasing sunshine thru the day with highs mainly in the low-
mid 60s. Should see dewpoints back down into the low 40s in
post-frontal air mass.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 334 PM EDT Monday...No significant weather expected
through the long-term forecast period. Best rain chances
(40-50% PoPs) during the extended to Saturday night into Sunday
as cold front moves from west to east across the North Country
in progressive mid-upper level flow pattern. Otherwise,
conditions appear mainly dry with seasonable temperatures for
late September. Generally looking for highs in the 60s, with
lows mainly in the 40s.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Marine stratus has left TAF sites in
eastern and southern VT with MVFR ceilings ranging from 1800 to
2200 ft. It doesn`t look like this cloud deck will be
dissipating any time soon. In fact, it may not be until sunset
that the ceilings finally begin to climb back to VFR. Elsewhere,
VFR conditions have persisted with gradient winds beginning to
increase as high pressure begins to slide east of the area. For
tonight, cloud cover will begin to increase from the southwest
as a warm front moves toward the region. As cloud cover
increases overnight, so should rain chances. By 10Z Tuesday,
rain will begin to move into northern New York and the leading
edge will move into eastern Vermont by 14Z. Periods of moderate
and even heavy rainfall is expected with this rainfall which
will lead to MVFR and occasionally IFR visibilities in heavier
rainfall. In addition on Tuesday, gradient winds will really
ramp up. After 12Z, it looks like most places will see winds
from the south around 15G25kt with some stronger winds possible
at KBTV.

Outlook...

Tuesday Night: Mainly MVFR, with areas IFR possible. Likely RA.
Wednesday: Mainly MVFR, with local IFR possible. Likely SHRA,
Chance TSRA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. Slight chance SHRA.
Friday: VFR. Chance SHRA.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Clay
NEAR TERM...Clay
SHORT TERM...Banacos
LONG TERM...Banacos
AVIATION...Clay