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Area forecast discussion
National Weather Service Burlington Vermont
736 am EDT Thu Mar 30 2017

high pressure will build across the area today with sunny to partly
sunny skies and seasonable early Spring temperatures. Low pressure
will approach and pass south of the area on Friday into Saturday
with a widespread wet accumulating snow expected. The snow may mix
with or change to rain in lower elevations on Friday. Dry weather
returns by Sunday into Monday before additional rains and snows
arrive by the middle of next week.


Near term /through tonight/...
as of 718 am EDT Thursday...forecast remains on track for today
with only noise-level tweaks to hourly temperatures/dewpoints
over the next few hours to match observational trends. Have a
great day.

Prior discussion from 437 am EDT Thursday...
nice weather expected across the area today as surface high
pressure bridges across the northeast. Sunny to partly sunny
skies are expected for most of the day under light northerly
breezes as high temperatures top out in the upper 30s to lower
40s, perhaps a few mid 40s in milder lower elevation locales.
High clouds will begin to move into the southwestern portions of
the forecast area toward late afternoon/early evening, and
thicken/lower across the entire area tonight in advance of our
next weather maker. Light snow will move into our far south and
southwestern counties late with minor accumulations of a dusting
to 2 inches possible, but the bulk of the precipitation for the
area should hold off until Friday. Lows tonight mainly in the


Short term /Friday through Saturday/...
as of 437 am EDT Thursday...the system referenced above will
take the form of surface low pressure and upper closed energy
tracking east from the Ohio Valley states tonight into Friday
and into the mid Atlantic and offshore environs by Friday
night/Saturday with widespread precipitation expected. Thermal
profiles continue to suggest p-type (rain/snow) will be governed
heavily by boundary layer temperatures, quite typical during
early Spring events. Some brief mix with sleet may be possible
across southern counties per mid level warm nose shown in most
recent NAM output. Given this model has a more northward surface
low track and is really the only output showing this have
omitted any reference to sleet at this point. In terms of timing
and amounts, the latest information suggests snow will arrive
into southwestern counties toward Friday morning and advance
northeast through the remainder of the forecast area during the
day on Friday into Friday night. A possible mix with or
changeover to a cold rain will be possible in lower elevations
below 1000 feet during the daylight hours. Complicating the
scenario will be how ground temperatures govern daytime
accumulations in these Lower, Valley sites. Climo would suggest
only a modest impact to roads in most areas through the day on
Friday with greater impacts expected Friday evening/night in
response to loss of insolation and slightly cooler temperatures.
Put considerable work into snow ratio output, leaning on the
lower side of guidance in the 8-10:1 range in lower elevations
and staggering progressively upward into the 10-13:1 range in
the higher terrain. Quantitative precipitation forecast from Friday into Saturday morning is a
blended output of NAM/GFS/consensus model/wpc blend with a
slight downward adjustment given the rather high output as
suggested by the NAM. This would support amounts ranging from
one third to two thirds of an inch north and two thirds to an
inch south. Snowfall output suggests 30 hour totals from 2-4
inches in the Champlain/St Lawrence Valley with only minor
impacts, 3 to 7 inches in much of the northern higher terrain
and lower elevations of southern VT, and 6 to 12 inches across
higher elevations of Essex County, New York and the southern Green
Mountains of Rutland/Windsor counties of Vermont. In these latter
areas, winter storm warnings and/or winter weather advisories
have been issued accordingly where difficult to locally
hazardous travel is expected. Given the wet nature of the snow,
some modest threat to trees/powerlines will also be possible
with the highest threat occurring across southern higher
terrain. Please see our winter weather Page at
www.Weather.Gov/btv/winter for specific accumulation forecasts
and probabilities. Highs on Friday ranging through the 30s with
lows Friday night in the upper 20s to lower 30s.

By Saturday the low pressure pulls away offshore with steadier snows
tapering to scattered rain/snow shower activity as the day
progresses. Any additional accumulations should generally be
confined to higher elevations during the morning hours as high
temperatures top out from the mid 30s to lower 40s.


Long term /Saturday night through Wednesday/...
as of 426 am EDT Thursday...some upslope snow showers will
continue into Saturday night across our northern Vermont zones
before ending early Sunday morning. Ridge of surface high
pressure will then build over our area for Sunday and Sunday
night. GFS and European model (ecmwf) then spread quite a bit apart from Monday
Onward. GFS is much more aggressive with southern stream and
northern stream low pressure systems phasing, and impacting our
area from Monday afternoon through Tuesday afternoon. The European model (ecmwf)
keeps US mainly dry through this period with the northern stream
low missing US to the north and southern stream low missing US
to the south. For Tuesday night and Wednesday region will once
again be dry with another ridge of high pressure over US. Both
European model (ecmwf) and GFS show a Great Lakes low pressure system passing
west of US late in the week and bringing more rain and the snow
showers to the area. Temperatures will be a bit below seasonal
normals for the extended portion of the forecast but trending
warmer towards the end of next week.


Aviation /12z Thursday through Monday/...
through 12z Friday...VFR conditions persist as surface high
pressure builds into the north country. Some stubborn clouds are
hanging around this morning but should be drifting south of our
area by 14z, gradually diminishing in coverage and lifting to
mid and high level clouds. Winds are 5-10 kts out of the north.
Will see an increase in high clouds late in the period and have
introduced vcsh early Fri morning.

Outlook 12z Friday through Monday...

12z Friday through 00z Sunday...MVFR/IFR in periods of rain and

00z Sunday through 00z Monday...areas of MVFR in scattered
light snow showers.

00z Monday through 00z Tuesday...mainly VFR conditions expected
as a ridge of high pressure builds into the region.


Btv watches/warnings/advisories...
Vermont...Winter Weather Advisory from 5 am Friday to 2 PM EDT Saturday
for vtz003-004-006>008-010-011-016>018.
Winter Storm Warning from 5 am Friday to 2 PM EDT Saturday for
New York...Winter Weather Advisory from 5 am Friday to 2 PM EDT Saturday
for nyz029>031-035.
Winter Storm Warning from 5 am Friday to 2 PM EDT Saturday for



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