Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
420 am EST Monday Feb 8 2016
a weak ridge of high pressure will keep the north country dry on
Monday before a deepening trough of low pressure produces widespread
light snow for Monday night into Wednesday. Total snow accumulations
will range from a dusting to several inches possible in the
mountains during this time period. Temperatures will continue to
average near normal for highs...but 5 to 10 degrees above normal
for overnight lows. Towards the end of the week expect a pattern
change that will bring much colder temperatures to the north
Near term /through tonight/...
as of 345 am EST Monday...expect generally a quiet morning today
as a weak ridge sits just in between a rapidly deepening coastal
low off the coast of Cape Hatteras in North Carolina and a
developing low over the Great Lakes. The coastal low will track up
the East Coast but will remain well south and east of the
benchmark which leaves the north country generally as spectators
to the snow and strong winds over the rest of New England.
The weak ridge loses its grasp this evening as the coastal low
tracks towards the north and there will be an increase in low
level moisture from the low developing over the Great Lakes with
generally easterly winds for most of the day. As the lower levels
become saturated there will be some light snow developing across
portions of southern Vermont. Latest hires guidance points to
light snow developing across most of Vermont through the evening
except for the immediate Champlain Valley where the easterly
downsloping winds may limit how much precipitation falls. Similarly there
will be light snow falling across the Adirondacks and limited
snowfall across the Saint Lawrence valley where the easterly
downsloping winds will keep totals lower.
Temperatures aloft at 925 mb will be between -6c to -8c through the day
and slowly cool to -8c to -10c. This will support maximum temperatures today
in the low 20s in the Northeast Kingdom and Adirondacks and in the
upper 20s to low 30s in the Champlain Valley. Expect lows Monday
night to be in the middle teens to lower 20s .
Short term /Tuesday through Wednesday/...
as of 420 am EST Monday...surface low and a closed upper low over
the Great Lakes will produce a period of light snow across the
region on Tuesday. Have gone with mainly likely probability of precipitation for Tuesday.
Expecting steady light snow to taper off to snow showers Tuesday
night and Wednesday. Looks like a period of cloudy skies with
chance of light snow through the period.
Long term /Wednesday night through Sunday/...
as of 420 am EST Monday...the region will remain under the
influence of an upper trough with a chance of snow showers
Wednesday night and Thursday. GFS model showing an Arctic cold
front will move through the region on Friday with a chance of snow
showers. Very cold Arctic air will pour into the region this
weekend with highs mainly in the single digits above zero Saturday
and Sunday and low below zero Friday night and Saturday night.
This will be the coldest air so far this winter season. Have
followed superblend guidance for this forecast.
The only fly in the ointment in this forecast is 00z European model (ecmwf) model
which now has a low pressure area forming off the Carolina coast
Friday night and then moves it northeast and deepens it as it
nears Cape Cod just inside the benchmark (40 north 70w) by 12z
Saturday. The GFS model has a flatter wave of low pressure and
moves it out to sea well south of New England Friday night and
early Saturday. The European model (ecmwf) continue to deepen this low as it takes
it to the Canadian Maritimes Saturday night. If the European model (ecmwf) model is
correct that would mean snow for the region Friday night and
Saturday. However...feel the European model (ecmwf) is an outlier at this time...as
this run of the European model (ecmwf) is a major change from previous runs which
were in agreement with the GFS on bringing in cold Arctic air into
the region this weekend. Thus...have stayed with the drier and
much colder superblend guidance for this weekend.
Aviation /09z Monday through Friday/...
through 06z Tuesday...weak high pressure over the area between
approaching coastal low and low centered over Great Lakes bringing
benign weather and light winds. Predominantly VFR ceilings through the
overnight hours at all terminals before ceilings become lowers late in
the day. Persistence forecast for much of the early portion of the period
as front remains stationary with generally light north wind. After
18z Monday coastal storm will spread VFR ceilings in from the south
with light snow expected at rut/mpv. Went ahead and included vcsh
at btv/pbg/slk beginning around 23z and then did go ahead and go
prevailing light snow shortly after 01-02z but didn't include any
visibility restrictions just yet.
Outlook 06z Tuesday through Friday...
06z Tuesday-12z Wednesday...MVFR/IFR in light snow.
12z Wednesday Onward...VFR with areas of MVFR/IFR in scattered to