Scientific Forecaster Discussion
fxus61 kbtv 222015
Area forecast discussion
National Weather Service Burlington Vermont
415 PM EDT Tue Oct 22 2019
gusty southerly winds will begin to diminish this evening as
widespread precipitation spreads over the area. A front will
move through during the overnight hours, bringing between 0.6 to
1.0 inch of precip between this evening and Wednesday morning.
Steady rain will taper off into some spotty showers during the
day Wednesday. The remainder of the week will feature daily
chances for showers, partly to mostly cloudy skies, and breezy
Near term /through Wednesday night/...
as of 349 PM EDT Tuesday...continued gusty winds and developing
widespread rainfall are the primary forecast concern for the
overnight hours as a cold front to our west is poised to push
through tonight. Ahead of the front, southerly flow has
increased through the day today thanks to a 45+ kt low level jet moving
overhead. Some of this momentum is sporadically mixing to the
surface, but given the strong warm air advection in place the
brunt of the strongest flow is staying aloft. Consequently,
winds will continue to be in the 5 to 15 mph range with some
gusts up to 25 mph possible through early evening. The exception
will be higher elevations (generally above 1500 ft) and Lake
Champlain and the immediate vicinity, which will see more
sustained 15 mph to 30 mph winds. Once the sun sets and
widespread rainfall develops this evening, winds will begin to
decrease as the boundary layer stabilizes.
In terms of precipitation, there may be some spotty warm air
advection-driven showers observed through early evening.
However, the more widespread rainfall still has yet to move
through and remains to our west. General timing of the start of
the more steady rainfall is between 3 PM and 8 PM over northern
NY, and generally between 8 PM and midnight in Vermont. The
heaviest rain will fall in the overnight hours before tapering
off into showers Wednesday morning. Total quantitative precipitation forecast between this
afternoon and Wednesday morning is on track for between two
thirds of an inch up to an inch.
After the front clears the area Wednesday morning, the remainder
of the day will trend drier...with the exception of some lake
effect showers lingering over parts of northern New York. These
showers will be light in nature however, and many areas likely
won't measure any precipitation at all. Despite the Post-
frontal southwesterly flow Wednesday, mid-level temps will
steadily fall through the day...with cold air wrapping around
the base of a mature cyclone lifting through central Canada. As
a result, expect some gusty southwesterly winds during the
afternoon, especially channeled up the Saint Lawrence valley.
Temperatures will be near seasonal norms.
Short term /Thursday through Friday/...
as of 414 PM EDT Tuesday...an upper level short wave passes to the
northwest of our area on Thursday bringing some unsettled weather
across the north country. During this time, windy conditions are
expected with the presence of a low level jet of 40-50kts at 850mb.
Surface winds will be from the southwest at 10-15kts and 25-35kts
across higher terrain. There remains a chance of precipitation
Thursday afternoon, especially across the western County Warning Area and among
higher elevations in New York and northern Vermont. This is supported by a
narrow swath of relatively higher pwats and weak instability with
cape values near 50 j/kg across northern New York and Vermont. In addition, the
southwest flow will result in shadowing across the Champlain Valley
and little chance of precipitation within this region.
Thursday night is expected to remain cloudy ahead of another upper
level short wave approaching from the west, although it is likely to
remain dry. Weak surface high pressure encroaches from the south
Friday morning, funneling moisture into our County Warning Area. Another chance of
precipitation returns Friday evening with the passage of an upper
level short wave, though the timing on its onset remains uncertain.
Due to the breezy conditions and overcast skies, temperatures will
remain at or above normal Thursday and Friday.
Long term /Friday night through Tuesday/...
as of 414 PM EDT Tuesday...conditions look to be drier Saturday as a
surface high pressure settles across the northeast. Beyond Saturday,
however, the GFS and European model (ecmwf) differ greatly regarding the arrival of
the next low pressure system. Due to lack of agreement in the models
and subsequent uncertainty, a chance of precipitation remains in the
forecast for the remainder of the period. In addition, the
temperatures during this time do not stray much from guidance.
Aviation /20z Tuesday through Sunday/...
through 18z Wednesday...expecting some low level wind shear,
turbulence, and general deterioration in flight categories
through 12z as a cold front moves through overnight. A 45+ kt
low level jet is overhead, but winds are generally under 20 kts
at the surface. This scenario will continue through the early
overnight hours, so have included mention of low level wind shear in most tafs
through around 06z. There will be some sporadic mixing of
gustier winds from aloft to the surface between 18z and 06z, so
expect some variation in surface wind speeds with occasional
stronger southerly gusts possible. Light to moderate turbulence
can also be expected, especially around higher terrain.
Rain associated with the front will move through overnight,
resulting in lowering ceilings and reduced visibilities during
the overnight hours. Northern New York taf sites can expect primarily
MVFR and IFR conditions between 00z and 09z, while Vermont taf sites
can expect expect primarily MVFR and IFR between 03z and 15z. Rain
will taper off into showers after 12z, and general improving
conditions can be expected.
Wednesday night: VFR. No sig weather.
Thursday: VFR. Chance rain showers.
Thursday night: VFR. Slight chance rain showers.
Friday: VFR. Chance rain showers.
Friday night: mainly VFR, with local MVFR possible. Chance rain showers.
Saturday: mainly MVFR, with areas VFR possible. Chance rain showers.
Saturday night: VFR. No sig weather.
Sunday: VFR. Slight chance rain showers.