Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
121 am EST Monday Feb 8 2016
a weak ridge of high pressure will keep our region dry on Monday
before a developing deep trough of low pressure produces a
widespread light snow for Monday into Wednesday. Snowfall
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. Much colder temperatures will arrive by late
week...but no significant snowfall is expected through the period.
Near term /until 6 am this morning/...
as of 1247 am EST Monday...expect a quiet evening with some cirrus
over the region. With generally northerly winds expect temperatures to
continue to drop through the evening. I continued to drop min
temperatures by another degree or so with low to middle teens expected
across the north country. Otherwise remainder of forecast in good
Short term /6 am this morning through Tuesday night/...
as of 330 PM EST Sunday...a light snow event is likely Monday
night into Tuesday night across our region associated with
developing trough of low pressure. The best moisture and forcing
associated with coastal system will pass well to our south and
east during this time period. All models are in good agreement
with closed cyclonic circulation lifting quickly northeast toward
the 40/70 benchmark by 00z Tuesday...while northern plains system
dives across the central Great Lakes. This system will remain
unphased...but enough moisture will be pulled back from coastal to
produce a general light snow across our County Warning Area from Monday night
through Tuesday. Soundings show very deep layer moisture across
our region...along with favorable snow growth region from 2500
feet to 11,000 feet on Monday night. However...upward vertical
velocity fields are very weak...and given no advection of air
because our County Warning Area will be directly under the influence of the upper
level system will result in light snow. Soundings show extremely
light winds of 5 to 15 knots through 600mb developing by 06z
Tuesday...with no favorable upslope component.
Expecting a fairly uniformed snowfall of a dusting to 2 inches
western County Warning Area....to 1 to 4 inches in our eastern zones by early Wednesday
morning. We will increase the probability of precipitation again to likely/low Cat with
highest values along and east of the Champlain Valley. Winds will
slowly shift to the northwest at 10 to 20 knots by early Wednesday
morning...supporting some upslope enhancement...as soundings
continue to show deep layer moisture. However...given we are under
the upper level trough and the associated cold thermal profiles
aloft...precipitable water values are only between 0.20 and 0.30 during this
period...as cold air does not hold as much moisture. Additional
light snow will continue into Wednesday.
We will be under general weak cold air advection with temperatures
cooling several degrees each day. Thinking highs generally in the
20s to near 30f on Monday with mainly 20s on Tuesday and lows just
several degrees cooler given the clouds and precipitation.
Long term /Wednesday through Sunday/...
as of 326 PM EST Sunday...large upper level trough over the Great
Lakes and Ohio Valley will move slowly east and result in mainly
cloudy skies along with scattered snow showers Wednesday through
Thursday. As low level flow becomes more northwesterly during this
period...expect the snow showers to become more concentrated over
the higher terrain and western slopes. More snow showers possible
on Friday as an Arctic cold front moves across the region. Behind
this front we will see the coldest air of the winter season so
far. Maximum temperatures Friday will be generally in the teens...with lows
Friday night zero to 10 below. 850 mb temperatures prognosticated to bottom out
around -30c on Saturday. Maximum temperatures Saturday will be mainly in the
single digits...and some northern areas will struggle to reach zero.
High pressure builds into the region Saturday night through
Sunday. Core of coldest 850 mb temperatures departs...but with light
winds...mainly clear skies...and the expectation of some snow
cover in most areas...expect mins to range from 5 to 15
below...with lower readings in the normally colder locales. Maximum
temperatures on Sunday only 5 to 15 above with some sunshine.
Aviation /06z 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