FXUS61 KBTV 131424
Area Forecast Discussion
National Weather Service Burlington VT
1024 AM EDT Fri Sep 13 2019
High pressure over the North Country today will give way to an
occluded low pressure system tracking out of the Great Lakes tonight
with gusty southerly winds developing this afternoon and continuing
tonight. Light rainfall spreads into the region late tonight into
early Saturday morning, then shifts eastward throughout the day.
Seasonable temperatures and drier weather will follow on Sunday but
another round of showers will be possible Sunday night. High
pressure will then settle into the region through the first half of
the upcoming week bringing warmer and drier conditions to the region.
.NEAR TERM /THROUGH SATURDAY/...
As of 1020 AM EDT Friday...Some valley fog remains across
eastern Vermont but has quickly been burning off under abundant
sunshine this morning. Otherwise, clear and sunny conditions are
expected with just a few wispy cirrus occasionally moving
overhead. Temperatures have rebounded nicely into the mid 50s
to lower 60s with the exception of Montpelier which is just now
beginning to break out of the fog. Winds will increase to 10-15
mph this afternoon as we continue to warm up and steepen the low
level lapse rates but the lack of any stronger winds aloft will
limit the winds this afternoon. Based on the 12Z guidance
starting to trickle in, I have slowed the rainfall moving into
northern New York tonight and have lowered PoPs and QPF for the
Champlain Valley with models now hinting at a 50 kt 850 jet.
More on this with this forecast package this afternoon.
Previous Discussion...After morning valley fog burns off, a
perfect late summer/early fall day is on tap for the North Country
as surface high pressure and a ridge aloft center over the
Northeast. Sunny skies will prevail with just a few passing high
cirrus clouds and high temps in the mid 60s to lower 70s. As the
high drifts eastward into the Canadian maritimes this afternoon,
increasing southerly winds are expected as the pressure gradient
begins to increase between the departing high and an occluded low
pressure system tracking out of the Great Lakes. Gusts up to 25 mph
are likely in the Champlain Valley during the afternoon and evening
hours, before winds increase markedly across much of the region
tonight as a strong low level jet of 40-50kts moves in ahead of an
approaching cold front. Due to the nocturnal nature of the jet,
mixing will be limited so the full potential of the wind won`t be
realized at the surface. Nevertheless, gusts in the 20-30mph are
likely with localized gusts up to 40mph possible along the Lake
Rain showers associated with the cold front shift into the region
after midnight across northern New York, and after sunrise across
Vermont. Some upslope and shadowing effects are expected due to the
strong low/mid level flow, and expect showers to be light in nature
because of this with overall QPF amounts generally less than a
quarter inch through Saturday. Bulk of the rainfall occurs Saturday
morning, then tapers off for the afternoon with the frontal passage.
Wind, clouds and precip tonight will keep temps mild in the 50s to
low 60s west of the Greens, but still cool eastward in the 40s.
Highs Saturday will run in the 60s.
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
As of 421 AM EDT Friday...Moisture axis pushes east of the North
Country on Saturday night with any remaining showers quickly
exiting. Lows will be above normal from lingering clouds falling
into the 50s. Much of Sunday should be dry. Southerly return flow
becomes reestablished, though it is not very strong and becomes
west-southwesterly during the day. Max temperatures should top out
near seasonal norms in the upper 60s to lower 70s. A shortwave will
advect across the area during the afternoon. It does not have much
to work with as forecast soundings indicate only a shallow layer of
moisture available, and with more westerly winds, warm advection and
low-level convergence will be lacking. It is possible that we see
mostly virga, but have offered some 20% PoPs for now.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 421 AM EDT Friday...Upper ridging is expected to build over the
Central US, with a shortwave digging into the North Country ahead of
this feature on Monday. Models generally agree on the synoptic set-
up, but disagree on placement and strength of certain features that
play a role in Monday`s weather. Surface high pressure will develop
across northern Quebec Province while a weak mid-level low slides to
our south. This should result in a favorable set up for overrunning
along a strengthening thickness gradient. The GFS is the most
aggressive, producing widespread rain over the Adirondacks and much
of Vermont, while the EC/CMC are much weaker with light
precipitation south of the forecast area. While a few SREF members
and most GEFS members have precipitation in the region, other
ensemble suites indicate they are not in the majority. Given the
pattern though, 20-30% PoPs seems reasonable for Monday.
Beyond Monday, deep layer ridging will be in control for the work
week. After a cool day on Monday, expect a gradual trend upwards
with near to above normal temperatures with dry, pleasant weather.
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Through 12Z Saturday...Mainly VFR conditions expected through
the period with the exception being lingering VLIFR fog at KMPV
through 14Z. Thereafter, just some increasing cirrus are
expected through the day with clouds lowering and thickening
after 00Z as our next system approaches. Light winds this
morning increase from the south/southwest through the day with
locally some gusts to 20kts at KBTV/KPBG through 00Z, then gusts
increase to 20-30kts for all sites except KMSS and KRUT.
Saturday: Mainly VFR, with areas MVFR possible. Windy with gusts
to 30 kt. Chance SHRA, Chance TSRA.
Saturday Night: Mainly VFR, with local MVFR possible. Slight
Sunday: VFR. Slight chance SHRA.
Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Monday: VFR. Slight chance SHRA.
Monday Night: VFR. NO SIG WX.
Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX.