Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
400 am EDT Monday may 4 2015
an upper ridge will push offshore as a weak cold drops south from
Quebec across the north country. Ahead of the front there will be
gusty southwest winds that will combine with very dry conditions
to produce near critical fire weather conditions in locations
below 2000 feet. Scattered showers will accompany the front on
Monday night with cooler air arriving on Tuesday returning the
region to near seasonal temperatures and dry weather through the
rest of the week.
Near term /until 6 PM this evening/...
as of 355 am EDT Monday...
fire weather danger remains the concern in the near term. The
combination of low relative humidities, gusty southwest winds, and
dry fine fuels will potentially cause dangerous fire weather
conditions. A Special Weather Statement is in effect today to
discuss the fire weather concerns. See fire weather section below
for complete details.
We will dry out today because of the upper level ridge that has
been in place for the previous couple of days and the southerly
winds at the surface. This will warm the area very quickly during
the day today. Low and middle level moisture is quite low across the
north country and thus overall cloud cover will be minimal. Expect
mostly clear skies through this afternoon before a cold front
begins to move south into the region. Clouds will overspread from
northwest to southeast ahead of the front and the atmosphere will
become very well mixed up to 7000 feet across the north country.
The well mixed atmosphere and steep low level lapse rate will
bring gusty winds ahead of the front gusting 20-30kts across much
of northern New York and 15-20kts across Vermont.
The dry air and good mixing will allow for temperatures across the
region to warm into at least the upper 70s for the second day in a
row with 80f being a real possibility in the Saint Lawrence and
Champlain valleys. With Lake Champlain still being quite cold the
air temperature over the lake will be significantly cooler and so across
the Broad Lake i've only got maximum temperatures today warming to around 70
and the near shore areas in the low to middle 70s.
Short term /6 PM this evening through Wednesday/...
as of 355 am EDT Monday...
by 23z this evening or 7pm, expect the first showers to start to
move into northern New York as the cold front draws closer to the
area. As the line of showers drops to the south and meets moderate
southwest flow expect it to struggle to hold together over the
Adirondacks and see the Champlain Valley become shadowed from the
showers with only light showers expected. In the higher terrain
however expect the orographic lift to combing with the weak
instability associated with a 500mb vorticity axis and produce a few
moderate rain showers especially over the northern Adirondacks and
southern and central greens. However widespread precipitation will
be light expecting total precipitation amounts to range from 0.10" to
0.30". Similar to the previous forecast with the weaker
instability I chose to leave out mention of ts in the forecast but
it wouldn't surprise ME to hear a few rumbles of thunder as the
line moves through New York.
Behind the front Monday night temperatures will fall into the middle 50s in
the Champlain Valley and upper 40s elsewhere. We will then move
into a pattern of near seasonable temperatures and dry weather as the
flow aloft becomes northwest and slight upper level ridging begins
Long term /Wednesday night through Sunday/...
as of 355 am EDT Monday...
dry and Spring-like weather expected through Friday.
European model (ecmwf) and GFS models are in generally good agreement through the
period. Thus...forecaster confidence is high.
European model (ecmwf) and GFS models show a ridge of high pressure will be over the
region Wednesday night through Friday.
A weak cold front will move south from Canada on Saturday
..so have gone with chance probability of precipitation for showers and a slight chance of
thunderstorms. Models showing frontal system will be over or just
south of the region on Sunday...so will continue with chance probability of precipitation
for rain showers on Sunday.
Aviation /08z Monday through Friday/...
through 06z Tuesday...mainly VFR conditions through the period.
A ridge of high pressure will move east of the region today. This
will allow for southerly surface winds to develop across Vermont
and northern New York today. Surface pressure gradient to tighten
across the region today...with south to southwest surface wind
gusts of 20 knots or greater to develop between 13z-15z Monday and
continue through 00z Tuesday. A cold front will move slowly east
from the western Great Lakes today and will move into the Saint
Lawrence valley in northern New York after 00z Tuesday. Expecting
light rain showers to develop across northern New York between
02z-06z Tuesday...with some local areas of MVFR possible.
Outlook 06z Tuesday through Friday...
06z Tuesday-12z Tuesday...mainly VFR but with areas of MVFR/IFR
in light rain showers as a weak cold front moves through the
12z Tuesday-00z Saturday...VFR conditions with weak surface high
pressure prevailing for much of the period.
breezy south to southwest winds of 10 to 20 miles per hour
with gusts to 30 miles per hour will occur between 11 am and 4 PM
Monday....with minimum relative humidity values between 26% and 36%.
A few higher gusts to near 40 miles per hour will be possible in the Saint
Lawrence valley and parts of the northern Adirondacks. The strongest
winds will be located across the Saint Lawrence valley...northern
Adirondacks...and parts of the Champlain Valley into northern
Vermont...while the lowest relative humidity values will be across southern Vermont.
These conditions combined with 60 to 90 day departure from normal
precipitation deficits of 2 to 4 inches have resulted in fine fuels
becoming very dry below 2000 feet...according to the Vermont
department of Forest...Parks and rec and New York state department
of environmental conservation. Given the near critical fire weather
conditions...we will highlight potential threat with a Special
Weather Statement at this time.
As a surface cold front approaches the Saint Lawrence valley and
northern Adirondacks after 4 PM Monday... relative humidity values
will increase as clouds and associated middle level moisture overspread
the region...with scattered rain showers developing by evening.
These showers will spread east into the Champlain Valley and most of
Vermont overnight...but precipitation will be light and mainly
confined to the mountains