Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 231735
Area Forecast Discussion
National Weather Service Burlington VT
135 PM EDT Thu Mar 23 2017
A strong area of high pressure will crest over the North Country
this afternoon bringing mostly sunny conditions and light winds.
Temperatures will moderate a bit, with daytime highs mainly in
the upper 20s to lower 30s. A warm front will approach from the
southwest on Friday, with overcast skies and a developing wintry
mix across the North Country. Some light accumulations of snow
and sleet are expected Friday morning before transitioning to
mostly rain later in the day. The frontal zone will become
quasi-stationary near or just south of our region over the
weekend, with the potential for additional mixed wintry
precipitation later in the weekend.
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
As of 713 AM EDT Thursday...Strong sfc anticyclone (1036mb)
centered over wrn NY at 11z/Thu will be our controlling wx
feature today as it translates ewd across the nern CONUS. A
chilly start at sunrise with -18F at KSLK and +3F at KBTV
(within 2 deg of a record low at BTV). Air mass will undergo
some moderation today, aided by sunny skies and a relatively
high late March sun angle. Looking for afternoon highs 27-32F,
warmest in the Champlain/St. Lawrence/CT river valleys. Once
nocturnal inversions mix out, will see NW winds generally 5-10
mph thru mid aftn, then becoming light and variable toward this
evening. PoPs NIL, but will see some increasing cirrus clouds
from the west late this afternoon into this evening.
.SHORT TERM /8 PM THIS EVENING THROUGH FRIDAY NIGHT/...
As of 200 AM EDT Thursday....High pressure shifts east of our
longitude overnight and into the Gulf of Maine by 09-12z Friday.
This will allow for a light S-SW return flow to develop. Aloft,
will see a warm front approaching from wrn NY and sern Ontario,
and increasing 850-700mb WAA will result in thickening mid-level
overcast. These factors will keep overnight temperatures
generally in the mid teens to lower 20s, with a tendency for a
slow rise in temps toward daybreak Friday, especially west of
the Green Mtns.
Moderately strong 850-700mb WAA with approaching warm front
brings developing stratiform precipitation beginning during
Friday morning from SW-NE. It appears thermal profiles will
initially support snow, with a transition to sleet/rain as the
day progresses. Subfreezing thermal profiles will persist
longest across central/ern VT and in the nrn Adirondacks, where
1-3" of wet snow/sleet are forecast. Should see generally 1" or
less wet snow in the Champlain Valley as PBL temperatures warm
more quickly thru the 30s. Could see some minor impacts to
travel especially around the time of onset of the mixed wintry
precipitation (and especially away from the Champlain Valley),
and will continue to highlight in the Hazardous Weather Outlook.
Afternoon highs on Friday generally 36-39F, except 33-34F
across portions of ern/nern VT.
First wave of low-level WAA passes to our east Friday
evening/night, but E-W oriented low-level frontal zone will
become quasi-stationary across nrn NY/nrn VT. May be a tendency
for a shallow nly wind shift after midnight with strong high
pressure building into wrn Quebec, so we`ll need to monitor
trends with the frontal position overnight with possible shallow
CAA near the intl border. Anticipate continued overcast skies,
but with just very light rain/drizzle or isolated pockets of
snow/sleet/freezing drizzle across far nrn areas. Temperatures
will generally hold in the low-mid 30s.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 309 AM EDT Thursday...Interesting forecast with rather
active period expected and above normal chances for mixed
precipitation. Large high builds down from Canada on Saturday
and pushes surface boundary southward out of the area...which
will help bring precipitation to an end during the morning
hours. Highs will range from the mid 30s along the Canadian
border to the upper 30s and mid 40s elsewhere. Northwest flow
aloft Saturday night continue to bring colder and drier air into
the region. An upper trough will move east from the Ohio Valley
and this will allow the boundary that moved out of our area on
Saturday to return northward into our region and enhance the
potential for precipitation...especially Sunday afternoon and
night. Thermal profile suggests mixed precipitation with surface
cold air holding in the longest across eastern Vermont Sunday
night into Monday. Precipitation should become rather widespread
Sunday night into the first part of Monday as the trough moves
across the area. Will have to monitor this situation closely in
case there will be a need for a winter weather advisory. There
will be a brief respite in precipitation Monday night into the
first part of Tuesday...but another trough of low pressure will
move toward the region later Tuesday into Wednesday and bring
more precipitation to the area. Still cannot rule out some mixed
precipitation...but at this time looking at either rain or snow
with this system. The precipitation should be fairly widespread
as well given the strength of the upper trough moving into the
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --Through 18Z Friday...VFR through 12Z as high pressure gives way
to approaching warm front and associated pcpn. SKC expected
through 00Z, then slowly thickening/lowering VFR OVC in the 00Z
to 12Z time frame. Winds light/modest northwesterly through 00Z,
trending light overnight. After 12Z Friday widespread snow
overspreads all terminals, likely transitioning to a
snow/sleet/rain mix from Champlain Valley terminals west toward
the end of this forecast cycle. Winds trending southerly 5 to 15
knots, most pronounced at KBTV/KPBG where valley channeling
effects may push gusts near 25 kts.
Outlook 18Z Friday through Tuesday...
18Z Friday through 18Z Saturday...widespread light mixed pcpn
likely, slowly settling southward and lessening in coverage by
Saturday afternoon affecting mainly southern terminals at that
point. Highest threat of mix to occur at northern terminals.
18Z Saturday through 12Z Sunday...trending mainly VFR/pcpn-free
as Canadian high pressure noses briefly southward into the area.
12Z Sunday through 12Z Tuesday...widespread mixed pcpn and/or
rain return to the region.
12Z Tuesday onward...light and spotty mixed pcpn transitions
toward a period of steadier rains by Wednesday.
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