Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
629 am EST Thursday Nov 26 2015
gusty south winds and mild temperatures will continue across the
region through Friday ahead of an advancing cold front pushing
east from the Great Lakes states. The front will swing through the
region later Friday afternoon into Friday night with scattered to
numerous showers. Behind the front a return of mainly dry and
seasonable weather is expected for the upcoming weekend and into
early next week. Additional energy will likely affect the area by
the middle of next week, though with moderating temperatures most
of the precipitation will likely fall as rain.
Near term /through tonight/...
as of 629 am EST Thursday...minor adjustments to temperatures and
dewpoints to match current observational trends. Otherwise
forecast remains on track. Have a great Holiday.
Prior discussion from 255 am EST Thursday...
mainly a persistence forecast through sunrise Friday as variable
middle to high cloudiness traverses the region along with gusty south
to southwesterly winds. 500 meter back-trajectory analysis from
this morning's National oceanic and atmospheric administration hysplit model run shows our air this afternoon
traces its source to the Delaware-Maryland-Virginia region yesterday which saw high
temperatures in the lower to middle 50s. Feel similar readings will
be achieved by later today in the Champlain and St Lawrence
valleys, with slightly cooler values (45 to 50) across the
Adirondacks, and especially eastern Vermont where a greater
maritime influence will occur. On the winds, gusts should easily
climb into the 15 to 25 knot range by afternoon if not sooner, a
result of a tight pressure gradient between strong maritime high
pressure and an approaching Great Lakes upper trough. So despite
the mild temperatures it will feel on the blustery side in many
By tonight more of the same as thickening middle to high cloudiness
occurs in advance of the upper trough and its attendant cold front
approaching from the northwest. However, deeper moisture and
dynamical lift along the front remain to our north and west so dry
conditions will continue. With occasionally gusty south flow
continuing overnight temperatures will hold nearly steady across
much of the area, generally holding in the 40s to around 50.
Short term /Friday through Saturday night/...
as of 321 PM EST Wednesday...the pressure gradient flow will keep
moderate to strong southerly flow in at the surface through Friday
morning as the middle level moisture and clouds increase over
northern New York. A strongly positively tilted trough will drag a
cold front through beginning Friday afternoon with antifrontal
style precipitation meaning that the precipitation will fall behind the wind
shift front. Boundary layer temperatures will remain warm through most of
the evening thus the precipitation will fall as rain before changing
over to a brief period of wintry mix and then transitioning to
light snow across most of the area early Saturday morning. Early
in the morning the higher terrain above 1500 feet will most likely
see snow showers while the lower valleys are expected to just see
some light flurries.
The available moisture on Saturday will be rapidly drying out as
the front pushes towards the Atlantic Ocean and thus the precipitation
should end early Saturday morning leaving behind strong cold air
advection under a building high pressure system. Expect temperatures on
Friday to remain warm under the southerly warm air advection and
stay in the middle to upper 50s before rapidly cooling behind the
front. Temperatures Friday night will be dependent on how far the front
crosses through the region but will generally be in the upper 20s
to low 30s behind the front. Then as the cold air advection
continues on Saturday expect temperatures to only be in the middle to upper
30s with lows that evening in the upper teens to low 20s.
Long term /Sunday through Wednesday/...
as of 334 PM EST Wednesday...the building dome of high pressure
will continue Sunday with seasonably colder temperatures through the
early week before a moderating shortwave ridge builds in aloft.
That weak ridge will cause the surface high to drift offshore
enabling surface return flow to develop and leaving to moderating
temperatures by middle week. The next system to impact the north
country looks to be a decent rain storm with relatively high
precipitable water but warm thermal profiles. Expect rain sometime
middle week and as the low tracks once again to the north of the
forecast area there could be some minor potential for some
orographic snow showers developing in the higher terrain by the
end of the week.
Aviation /12z Thursday through Monday/...
through 12z Friday...VFR through the period. Low level wind shear and enhanced
southerly wind gusts to be the primary aviation concern for the
Expect generally clear skies below 200 above ground level through 18z under gusty
south flow in the 15 to 30 knot range. After 18z ceilings remain VFR
though gradually lower into the 070-150 above ground level range into the
overnight hours under continued gusty south flow. Low level wind shear a concern
at any terminal where winds lighten. Primary low level wind shear concern at kslk.
Outlook 12z Friday through Monday...
12z Friday through 18z Friday...bkn/ovc VFR.
18z Friday through 18z Saturday...trending to MVFR in rain
showers as a cold front drops south into the region from Canada.
Some MVFR/IFR in snow showers possible 00z-12z Saturday as
12z Saturday through 00z Tuesday...VFR/high pressure.
as of 255 am EST Thursday...
a lake Wind Advisory remains in effect today...
Modestly strong and gusty south winds of 20 to 30 knots are
expected on the lake today and will likely continue into tonight
before slowly abating on Thursday. The highest winds to generally
occur across the central and northern portions of the lake where
significant wave heights will range in the 2 to 4 foot range with
a moderate chop. Bays and inlets with open southerly exposure will
also see waves on the higher end of the forecast range. These
conditions will pose a hazard to small craft operating on the lake
over the next 24 hours.