Scientific Forecaster Discussion
fxus61 kbtv 191843
Area forecast discussion
National Weather Service Burlington Vermont
243 PM EDT Thu Sep 19 2019
strong high pressure will dominate regional weather conditions
through Sunday with fair and dry weather expected. Mild to warm
afternoon highs and seasonably cool overnight lows will be the
rule with generally light winds. The next chance of showers
arrives by Sunday night into Monday with the approach of a cold
Near term /through Friday night/...
as of 232 PM EDT Thursday...a persistence forecast methodology
will be used with this package update with deep layer ridging up
to 250 mb anchored across the northeastern third of the nation
over the next 42 hours. Outside some passing thin high clouds
mainly clear skies are expected and with the surface high center
gradually edging to our east over time air mass moderation will
occur as synoptic low level flow trends light southerly.
Tonight's lows should reflect this, being not as cool as this
morning - mainly upper 30s to lower 40s in the mountains and mid
40s to lower 50s in the broad valleys. Corresponding highs on
Friday should range milder through the 70s with Friday night
lows some 6 to 10 degrees milder than tonight - 50s. Enjoy!
Short term /Saturday through Saturday night/...
as of 241 PM EDT Thursday...Saturday will be the sunnier of the two
days this weekend with the upper level ridge axis directly
overhead. Temperatures will warm nicely under this deep layer
ridge given strong warm air advection which should yield
afternoon highs in the mid to upper 70s with readings in the
lower 80s in the Champlain and Saint Lawrence valleys. The GFS
is trying to create some shower activity Saturday afternoon
which is by far the outlier and looks very unlikely given that
the dynamics will be well off to our north and west on Saturday.
Ended up increasing cloud cover slightly but kept pops at 0% as
subsidence should keep any shower activity at Bay. Saturday
night is going to be very mild with southerly winds and clouds
increasing ahead of an approaching cold front. This should keep
overnight lows in the mid 50s to mid 60s.
Long term /Sunday through Wednesday/...
as of 241 PM EDT Thursday...Sunday, for the most part, should be a
pretty nice day across the north country albeit a touch on the windy
side. With the upper level ridge axis and the surface high beginning
to shift eastward, we will see the pressure gradient increase
throughout the day on Sunday. Winds won't be too strong with winds
gusting in the 18 to 25 mph range. Southwesterly flow in the mid-
levels will strengthen the warm air advection across the region
which will yield even warmer temperatures on Sunday with highs in
the upper 70s to mid 80s. It may actually feel cooler on Sunday with
the stronger winds adding a bit of a "wind chill" to how it feels
outside. The approaching cold front appears it'll be slower to
impact the region as the trough out west doesn't look as robust as
it once did. This will slow the onset time of rainfall in the Saint
Lawrence valley until sunrise on Monday before spreading eastward
throughout the day.
The rainfall on Monday still looks unimpressive with the main upper
level forcing remaining north of the international border. There
will be a nice ribbon of moisture of 1.5+" precipitable water values
but the lack of dynamics should produce less than optimal rainfall
rates. The southwesterly jet won't be doing US any favors in the
Champlain Valley where it still looks like some shadowing could be
observed. Overall rainfall amounts still look much less than a
quarter of an inch but some of the western slopes of the green and
Adirondack Mountains may do a little better. Showers will continue
through the day on Monday but taper off Monday night and exit the
region by Tuesday morning.
A return to deep layer ridging will develop on Tuesday but will be
rather short lived. This should yield another nice day across the
north country with temperatures right around normal following the
cold front on Monday. The overall longwave pattern will become less
amplified heading into Wednesday which will prevent and large warm-
ups or cool-Downs but it does bring rain chances back to the region
on Thursday as a strong shortwave traverses the northwesterly flow
Aviation /19z Thursday through Tuesday/...
through 18z Friday...strong high pressure will lead to VFR
through the 24-hr forecast period with mainly sky clear outside a few
passing high clouds above 200 above ground level. Winds generally south 3 to 7
kts through 00z with some variability to SW/se depending on
terminal, trending nearly calm overnight. After 12z Friday wind
regime trends similar to this afternoon's conditions.
Friday night: VFR. No sig weather.
Saturday: VFR. No sig weather.
Saturday night: VFR. No sig weather.
Sunday: VFR. No sig weather.
Sunday night: VFR. Chance rain showers.
Monday: mainly VFR, with areas MVFR possible. Likely rain showers.
Monday night: mainly VFR, with local MVFR possible. Chance rain showers.
Tuesday: mainly VFR, with local IFR possible. No sig weather.