Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
322 PM EDT Friday Jul 3 2015
high pressure will generally provide mainly fair and seasonably
warm temperatures for the Holiday weekend. Outside a few widely
scattered showers across northern New York and northern Vermont
later Saturday afternoon into Saturday night, dry weather is
expected. The next chance of more widespread showers looks to
occur by Tuesday into Tuesday night with passage of a weak frontal
Near term /until 6 am Saturday morning/...
as of 310 PM EDT Friday...another quiet night across the region
as high pressure slides slowly east offshore the New England
coast. Thus looking at mainly clear to partly cloudy skies as
temperatures bottom out in the middle 40s to lower 50s with customary
cool spots. Some patchy br/fog again possible, most favored in our
eastern Vermont hollows and river bottoms.
Short term /6 am Saturday morning through Sunday night/...
as of 310 PM EDT Friday...high pressure continues to slide east
into Saturday allowing a northern stream shortwave trough to
approach and cross the area by Saturday night. As was the case
yesterday, believe model dewpoints, resultant planetary boundary layer instability and
quantitative precipitation forecast output is overdone with this feature. Low to middle level back
trajectory analysis from today's hysplit runs suggest our source
air tomorrow originates from southern New York into Pennsylvania so
slightly higher dewpoints on light southerly return flow seem
reasonable, just not to the extent of the deterministic runs. Best
shot at seeing a stray shower tomorrow afternoon appears to occur
across the higher terrain of the Adirondacks where weak planetary boundary layer flow
will support slope flows and localized Theta-E convergence.
Outside of this area just a token 10-20% threat with most areas
remaining dry over the course of the day. Highs tomorrow generally
in the 70s under variable middle to high cloud cover.
By tomorrow night aforementioned shortwave trough swings through the
region with clouds and perhaps a few showers across our northern
counties. Again, quantitative precipitation forecast will be light with coverage being scattered
at best and many areas remaining dry, especially south.
Low temperatures a bit milder given variable clouds, mainly in the
50s to around 60.
By Sunday into Sunday night upper trough swings east with deep layer
high pressure returning in earnest across the region. Other than a
few lingering morning showers far northeast dry weather is expected.
Temperatures will average very close to early July normals with
highs in the upper 70s to lower 80s and overnight lows in the middle
50s to lower 60s.
Long term /Monday through Friday/...
as of 322 PM EDT Friday...
A hint of Summer next week as heights and temperatures rise to or
just above normal with a surge of moisture and some thunderstorms
Models in agreement that short wave ridging Monday should bring a
nice warm and dry day in the 80s with 850 temperatures rising to 14-15c.
Models similarly increasing humidity and instability
(1000-2000j/kg cape) on Tuesday ahead of a frontal system as
southwest flow advects moisture into the region. So that will
increase our chances of showers and thunderstorms through through
Tuesday night. Little change in 850 temperatures so temperatures again in the
Where models differ is on how fast the frontal system moves
through with GFS bringing front through by Wednesday morning while
European model (ecmwf) is slower and brings it through later in the day. Both
models show upper trough weakening and lifting north, so not
expecting a deepening trough like we've had lately. The timing of
the front would make a significant difference in the convective
probabilities, so went with a blend with showers and a slight
chance of thunderstorms hanging around on Wednesday. Temperatures a bit cooler
Some uncertainty continues Thursday-Friday as flow aloft is generally
westerly with weak troffing so can't completely rule out a shower
with temperatures near normal for this time of year (80/60).
Aviation /19z Friday through Wednesday/...
through 12z Saturday...VFR conditions will prevail through period
with the one exception being potential MVFR/IFR conditions for
kslk/kmpv due to fog after 06z Sat.
Scattered cumulus clouds at or above 6000 feet will diminish around sunset. High
cirrus/cirrostratus clouds with an upper level trough will move
into the region tonight lowering from 30k feet down to 20k feet or
even a bit lower Saturday. Some cumulus development @ 5-6k feet possible
again tomorrow midday.
Winds will be light (10kts or less)with local southeast lake wind at pbg
and variable valley/terrain forced winds elsewhere.
Outlook 18z Saturday through Tuesday...
18z Sat-sun...mainly VFR. Isld MVFR -shra over the higher terrain.
Monday...mainly VFR under high pressure. Local LIFR fog possible kmpv/kslk.
Tuesday..mainly VFR. Scattered MVFR thunderstorms and rain with frontal passage Tuesday night.
Wednesday...mainly VFR. Scattered MVFR Post frontal -shra.