Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
330 am EDT sun Oct 26 2014
cloudy skies and scattered showers will affect the region
today...though precipitation should generally be light and taper
off by this afternoon across the lower elevations. High pressure
will slowly build into the region for Monday into Tuesday.
Temperatures on Tuesday will be quite mild with many spots
climbing above 60 degrees. More showers are expected by later
Tuesday into Tuesday night as a cold front crosses the area.
Near term /until 6 PM this evening/...
as of 330 am EDT Sunday...forecast remains more or less on track
for today as upper shortwave energy pivots east-southeast across the area.
Thus looking at mainly cloudy skies and scattered showers...most
numerous this morning when best positive vorticity advection and moisture swing through. By
this afternoon precipitation becomes increasingly confined to the
higher elevations in near neutral to slightly unblocked flow as
suggested by this morning's local WRF model runs. Regardless...any
precipitation that does fall today will be light so certainly not
a washout. Latest forecasts suggest freezing levels will continue to
slowly fall to around 3000 feet today so the summits will likely
get a dusting to perhaps an inch or so...especially across the
north. High temperatures a blend of available guidance suggesting
values should top out from the middle 40s to the lower 50s in most
Short term /6 PM this evening through Tuesday/...
as of 330 am EDT Sunday...shortwave/closed 500 mb low continues to
pull away from the region tonight into Monday with lingering
higher elevation snow showers coming to an end as weak high
pressure builds east from the central states/Great Lakes. Lows
tonight in the 30s to around 40...with highs on Monday similar to
today...middle 40s to lower 50s. For now have suggested that variable
morning clouds will give way to partial afternoon sun as upper
flow trends confluent and anticyclonic. So despite the rather cool
temperatures it shouldn't be too bad of a day...especially by
later in the day.
By Monday night models remain consistent in showing a warm front
advancing northeast into the region along with increasing clouds and
chances for rain showers. Better moistre/isentropic lift looks to
occur across our northern and western counties overnight where i've
mantained chance probability of precipitation. Lower values further south into
central/southern Vermont. Models also showing a band of steeper middle level
lapse rates and negative SW values along leading edge of strong 850
mb warm thermal advection associated with the front. Thus an outside
shot of elevated thunder will be possible generally from the
Champlain Valley west and north into northern New York overnight.
With increasing clouds and flow trending southerly over time low
temperatures will be more uniform and a tad milder...generally upper
30s to middle 40s with readings actually trending steady or slowly
As we progress into Tuesday the warm front will clear north and east
with the forecast area becoming briefly embedded in deep
southwesterly flow ahead of an advancing cold front across the Great
Lakes. Outside an early shower far north through middle morning a
mainly dry day is expected. Early indications suggest the planetary boundary layer will
be rather shallow with only limited mixing to about 2 kft or so.
Thus hesitant to go too warm...but with blended 18z 925 mb temperatures
ranging from 8-13c east to west will still lean toward the milder
side of guidance offering highs from the upper 50s to lower 60s
east...lower to middle 60s Champlain Valley into the dacks...and 65 to
Long term /Tuesday night through Saturday/...
as of 330 am EDT Sunday...surface low shifting northward from the
Great Lakes to east of James Bay drags a thermally strong but
somewhat moisture lacking cold front tracks through the region
Tuesday night into Wednesday morning. Medium range guidance has
been tracking this feature pretty well the past few days and now
are in good agreement on timing and strength...so with increased
forecaster confidence have offered likely probability of precipitation for rain showers
Tuesday night even though I expect the overall quantitative precipitation forecast to be rather
light...<0.10" in general.
Behind the front zonal to southwesterly flow develops aloft Wednesday
night through Thursday night as another upper trough takes aim on
the Great Lakes and northeast. Looking at generally dry conditions
for this period and a return to more fall-like temperatures with lows in
the 30s highs in the 40s. Going into the end of the week and weekend
a deep and seasonally cold upper trough digs southward from west of
James Bay into the northeast. Latest guidance is in good agreement
with the overall southward push of cold air and low/mid-level
temperature profiles...but differ significantly on the strength and
track of attending shortwave energy. The European model (ecmwf) is weaker and depicts
more of an open wave at 500mb...while the GFS develops a much more
potent shortwave which closes off Friday night over the middle-Atlantic
and southern New England states. The resulting quantitative precipitation forecast is fairly dry on
the European model (ecmwf)...and pretty wet on the GFS. Hard to tell 5-7 days out
which will be correct...so will play some middle-chance probability of precipitation for
now...but my gut tells ME the European model (ecmwf) is on the right track. Stay
Aviation /08z Sunday through Thursday/...
through 06z Monday...VFR conditions currently across the region
will trend towards MVFR as an upper level disturbance and
secondary front pushes into the region towards daybreak.
Northwesterly downslope flow should keep ceilings VFR at kpbg/kbtv
but elsewhere ceilings lower to MVFR after 10-13z. Associated showers
shift into northern New York after about 10z...and into Vermont
after 13z lasting just a few hours at kmss but longer at
kslk/kmpv/krut with upslope flow causing precipitation to become more
terrain-oriented.Southwesterly wind of 5-10kts overnight turn
west/northwest after 12z Sunday increasing to 08-15kts...with
some gusts up to 20kts possible.
Outlook 06z Monday through Thursday...
06z Monday - 12z Monday...a mix of MVFR and VFR continues
associated with lingering lower ceilings and terrain-driven
12z Monday - 12z Tuesday...VFR under building high pressure.
12z Tuesday - 18z Wednesday...VFR with some areas of MVFR in rain
showers as a frontal system moves through the region.
18z Wednesday - 00z Friday...VFR/MVFR ceilings in northwest flow and
scattered rain or snow showers over higher terrain.