FXUS61 KBTV 131753
Area Forecast Discussion
National Weather Service Burlington VT
153 PM EDT Sun Oct 13 2019
High pressure over the North Country today will provide a
beautiful fall day with increasing sun through this afternoon. A
weak front will move through Monday, accompanied by some clouds
and a few spotty light showers. The next chance for widespread
rainfall comes Wednesday as a low pressure system moves through
the area. Temperatures will be close to seasonal norms through
Wednesday, then turn noticeably cooler Thursday and Friday
behind the low.
.NEAR TERM /THROUGH MONDAY/...
As of 118 PM EDT Sunday...No changes for 130 pm update, going
forecast is in great shape. Previous discussion follows.
A weak frontal boundary is departing Vermont to the east. Low
clouds along and just behind the boundary will lift through the
morning today, giving way to ample sunshine by the afternoon.
Surface high pressure will crest overhead mid- day, followed by
a gradual increase of return southwesterly flow for the
remainder of the day. Despite a brief dip in 850 mb temps this
morning, WAA on the strengthening southerly flow this afternoon
will allow for high temperatures again in the low to mid 60s.
Going into the overnight, skies will remain mostly clear.
However, increasingly southwesterly flow in the low- levels will
prevent overnight temperatures from falling too sharply. Have
forecast lows in the upper 30s to mid 40s.
Monday morning, the expansive occluded low pressure system over
the Great Lakes Region will lift northeastward through Ontario
and into Quebec, pushing a weak cold/occluded front through the
North Country as it lifts out. Low-level and mid-level
instability will increase over northern NY and VT Monday in
response to the cold pool moving overhead. The increased
instability along with weak forcing associated with the
boundary will allow for a few light showers to develop during
the day. Moisture is limited however and upper-level support is
weak (nonfavorable upper jet position, best DPVA removed
further to the north towards the center of the low...). Thus,
QPF will be very limited with only a trace to a few hundredths
of an inch expected. The best chances for any measurable precip
will be over northern NY where low-level moisture will be
slightly enhanced downstream of Lake Ontario.
Temperatures do fall a bit behind the boundary, so there will be
an east- west gradient in high temperatures Monday. Northern NY
can expect temps to top out in the mid 50s to low 60s, VT will
see slightly warmer readings in the low to mid 60s.
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 323 AM EDT Sunday...A few rain showers will linger across the
Northeast Kingdom Monday evening following the weak frontal occlusion.
Based on the thermodynamic profiles at the time, the zero degree
850 mb isotherm will still be west of Vermont which will prevent
any precipitation from mixing with snowfall through the Monday
night period prior to the showers tapering off. Temperatures
Monday night will be on the chilly side with several locations
across northern New York and northeastern Vermont dropping near
or just below freezing while other locations drop into the mid
to upper 30s. Dry air will quickly filter in from the west
Monday night which should yield mostly clear skies developing
from west to east after midnight. Shortwave ridging in the mid-
levels coupled with surface high pressure will build across the
North Country throughout the day on Tuesday which will continue
to bring mostly clear skies to the region. Honestly, Tuesday
looks to be the nicest day of the week with light winds and
clear skies but it could be a touch on the chilly side with the
cold core upper level low continuing to push eastward. Still,
given the abundant sunshine on Tuesday, high temperatures will
likely rebound toward the lower to upper 50s. Cloud cover will
begin to build back into the region Tuesday night ahead of the
next storm system which will help keep low temperatures a few
degrees warmer than Monday night with temps generally in the mid
30s to lower 40s.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 323 AM EDT Sunday...Winds will begin to increase Wednesday
morning as the pressure gradient begin to tighten across the region.
A strong surface low will track across the Great Lakes and just
north of the international border throughout the day on Wednesday.
As this happens, a secondary low will form along the triple point
just off the coast of Delaware. As is common with double barrel low
features likes this, the big question is when the secondary low
becomes the dominant feature. Deterministic guidance continues to
remain in very good agreement both spatially and temporally with the
second low forming just after noon on Wednesday. However, there is a
touch of disagreement to how far east or west this low is going to
track through the day on Wednesday. The concern with this being that
if the low takes the GFS track, which is the western track, the
North Country will get into the area of strong frontogenesis which
could create strong banded like structures which could produce some
heavy rainfall. On the other hand, if we looks at the eastward ECMWF
solution, the area of strong frontogenesis would set-up across
coastal New England with the North Country seeing more of a light to
moderate stratiform rainfall event.
Now for some details. The winds on Wednesday don`t look to overly
strong but should be in the 15-25 mph range with some gusts up to 35
mph. Due to the weakening to our northwest, the strongest gradient
should develop over coastal New England. In terms of rainfall, run
total accumulations through Thursday morning on all guidance is
between three quarters of an inch and an inch and a quarter. If you
remember the banded rainfall potential the GFS shows, there could be
some locally higher amounts if that track ends up panning out.
Nevertheless, flooding looks unlikely given how progressive the
system is expected to be and rivers have returned to base flow after
the rain event several days ago. Still, we will continue to monitor
the potential for any flooding in the coming days as we iron out the
Rainfall will begin to taper off late Wednesday night closer to
Thursday morning from west to east. This reprieve in precipitation
should be rather short-lived as shower activity will quickly develop
during the mid to late morning hours on Thursday. Strong cold air
advection will help steepen the low level and mid level lapse rates
which will help produce instability showers. Decent forcing
associated with the upper level low as it begins to slide east of
Vermont will act in unison with the weak instability to help keep
showers going through much of the day Thursday and even into the
overnight hours. At this point, precipitation type begins to come
into play. Much of Vermont should start seeing 850 mb temperatures
near or below 0 degrees C which will be conducive for rain showers
at higher elevations (above 2000 ft) to mix with or change over to
snow. It`s a little too early to guess how much snow may fall at
summit level but it does look like a dusting to minor snow
accumulations does look possible late Thursday.
Any lingering shower activity will taper off Friday morning as deep
layer ridging begins to establish itself. This will bring the return
of drier weather and a warm air advection regime. Temperatures will
be 5-8 degrees below normal on Thursday and Friday but will trend
back to above normal values over the weekend.
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Through 18Z Monday...Predominantly VFR conditions expected for
the 24 hr TAF period as high pressure builds in. Light and
variable winds will become southerly this evening and remain
southerly under 10 kts for the remainder of the TAF period.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Definite RA.
Wednesday Night: Mainly MVFR, with local IFR possible. Definite
Thursday: Mainly MVFR, with local IFR possible. Likely SHRA.
Thursday Night: Mainly MVFR, with local IFR possible. Chance
SHRA, Chance SHSN.
Friday: Mainly MVFR, with local IFR possible. Slight chance SHRA.