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Area forecast discussion
National Weather Service Burlington Vermont
934 am EST Fri Dec 6 2019

Synopsis...
weak low pressure will bring an additional round of light snows
to the region today through early evening. Mainly dry and
colder weather arrives in the wake of this system later tonight
into Saturday before temperatures rebound nicely by this coming
Sunday. The milder trend continues into early next week with
increasing chances for rainfall by Monday afternoon into
Tuesday.

&&

Near term /through Saturday/...
as of 928 am EST Friday...only minor updates needed with the
forecast in good shape. Did tweak snow amounts a bit based on
12z high res guidance streaming in, which shows a strong
deformation band setting up across south-central Vermont, along with
good ascent in the dendritic growth zone appearing more likely
as well. Also refined quantitative precipitation forecast just a bit to capture the better
spatial depiction of the newer guidance. With that, changes were
fairly minimal, but portions of Rutland County could see some
moderate to locally heavy snowfall rates within a short-lived
mesoscale band during evening rush hour. For now, will continue
with an Special Weather Statement and watch observations closely for any further
updates.

Prior discussion...
the forecast remains on track for today showing another light
snow event affecting the region from mid morning Onward into
early evening. Northern stream clipper- type energy will track
from the eastern Great Lakes through the Mohawk Valley this
afternoon before exiting offshore later this evening. As is
typical with this type of system, primary mid- level
frontogenetical forcing will set up immediately north of the low
track and have maintained higher snowfall amounts across
southern areas accordingly. Leaned more heavily toward nbm snow
ratios and a multi-model consensus on qpf, downplaying the
higher NAM output which appears overly aggressive with a weaker
Continental system such as this. This yields snowfall totals of
a dusting to 2 inches in the northern valleys, 1-3 inches across
the Adirondacks and higher elevations of the northern greens,
and 2-4 inches across southern Vermont with perhaps a few spot 5
inch totals at elevation there. Highs today to remain
seasonably cold under a light wind regime - 20s to around 30.

Steadier light snows will taper off through the early evening
hours as best forcing exits quickly east leaving only scattered
flurries/snow showers in elevated terrain overnight. Some
partial clearing will be possible in the Champlain Valley and
southern Vermont after midnight with low temperatures bottoming out
mainly in the teens.

Then seasonably cold on Saturday outside a few lingering
flurries as strong 1030+ hpa surface high builds into the
region. Still some variable cloud cover with moisture becoming
trapped beneath building synoptic mid-level inversion but no
appreciable accumulations are expected. High temperatures to
range through the 20s under light northwesterly winds.

&&

Short term /Saturday night through Sunday/...
as of 429 am EST Friday...Saturday night will feature surface
high pressure ridging into the northern New York and Vermont
area, as well as an upper level ridge moving in. Minimum
temperatures Sunday morning will be cold, mainly single digits
to around ten degrees. On Sunday, surface high will slide
eastward off the New England coast, and south-southwesterly
return flow develops. Temperatures will warm into the lower 30s
to lower 40s, warmest in the Saint Lawrence valley. Pressure
gradient increases during the day and winds will gust to 30-40
mph, higher over Lake Champlain. Some clouds will also move into
the area on Sunday afternoon with increase in mid level
moisture.

&&

Long term /Sunday night through Thursday/...
as of 429 am EST Friday...Sunday night onwards will feature
more active weather with several systems impacting the north
country. Mid/upper level ridge remains anchored off the
southeast Continental U.S.. developing southwest 925mb to 850 mb jet of 40
to 50 knots advects a very warm air mass into the area. Warm air
advection later Sunday night into Monday morning will bring
developing rain showers, with possible mixed precipitation early
Monday morning where some cold air remains trapped in the
valleys east of The Greens. Surface low deepens and tracks
northward through the Great Lakes region Monday night into
Tuesday, eventually sharp surface cold front reaches our area
later Tuesday. Precipitable water values climb above 0.75" with
flow off the Gulf of Mexico and convergence just ahead of
approaching cold front. Jet dynamics also aid in moisture
advection and convergence, therefore could see some enhanced
rainfall amounts though it's a bit far out to zero in on those
details just yet. Still think that rainfall will range from
about a quarter of an inch to three quarters of an inch, locally
around an inch in favorable southwest upslope regions of the
dacks and greens. Temperatures will be mild Monday and Tuesday
with warm air advection despite clouds and precipitation moving
in generally ranging through the 40s but some spots will get
close to 50. Temperatures will fall sharply behind departing
cold front later Tuesday afternoon and overnight, and winds will
become gusty out of the west. Good mixing develops with steep
surface to 850 lapse rates, winds once again gusting to about 40
kts. Temperatures will trend to below normal following this
system through the end of the week. Flow will become favorable
for some lake effect snow showers in northern New York on
Wednesday also.

&&

Aviation /15z Friday through Tuesday/...
through 12z Saturday...a deterioration to widespread MVFR/IFR
in light snows expected at all terminals expected in the 12-21z
time frame as weak low pressure tracks through the area. Worst
conditions expected at krut where a period of moderate snows
are possible this afternoon. Winds light and variable,
generally less than 5 kts through this period.

Light snows then taper off west to east in the 21-03z time
frame as winds trend light north/northwesterly around 5 kts and
cigs lift to a mix of VFR and MVFR into the overnight hours.

Outlook...

Saturday: VFR. No sig weather.
Saturday night: VFR. No sig weather.
Sunday: VFR. Windy with gusts to 30 kt. No sig weather.
Sunday night: VFR. Windy with gusts to 30 kt. Chance shra, chance
shsn.
Monday: mainly MVFR, with areas VFR possible. Definite ra, likely
freezing rain.
Monday night: mainly IFR, with areas MVFR possible. Definite rain.
Tuesday: mainly MVFR, with areas IFR possible. Chance ra, chance
rain showers.

&&

Btv watches/warnings/advisories...
Vermont...none.
New York...none.

&&

$$
Synopsis...jmg

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