Area Forecast Discussion
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FXUS61 KBTV 240236
Area Forecast Discussion
National Weather Service Burlington VT
1036 PM EDT Thu Mar 23 2017
Clear skies will give way to increasing clouds and the threat
of light snows by tomorrow morning as a warm front pushes into
the area. Mixed precipitation or rain will be likely on and off
into the coming weekend as this front waffles south and north
across the region. Temperatures will moderate back toward more
seasonal late March values through the period.
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 1026 PM EDT Thursday...Forecast elements in good shape
this evening with increasing high clouds spreading from west to
east across our FA. Radar shows very light returns across
northern NY/VT...but low levels are very dry so precip is not
reaching the ground. Upstream water vapor shows potent s/w
responsible for convection over Lake MI will quickly move east
and approach the SLV by 10z. This energy combined with moderate
warm air advection and deep layer moisture developing on south
to southwest winds will help to enhance a band of light to
moderate snow across our cwa on Friday. Expecting a period of
snow accumulation with 1 to 3 inches likely...except 3 to 5
inches in the mountains of central/northern VT...including the
northeast Kingdom. Would not be surprised summits from
Killington Peak to Mt Allen to Mansfield to Jay Peak get 4 to 8
inches by midnight Saturday. NAM and local WRF`s continue to
show qpf between 0.50 and 0.75 with most falling in the form of
snow...especially in the mountains...with a mix of rain/snow in
the valleys by Friday afternoon. Warming bl temps will limit
snow accumulations in the valleys. All covered well in current
grids. Temps range from single digits NEK to mid/upper 20s
SLV/CPV tonight with developing southerly winds after midnight.
Previous Discussion Below:
Mostly clear skies with light winds will see high clouds
spreading from the west throughout tonight.Temperatures will
bottom out early given the clear skies (5 to 15 above in the
mountains/teens to lower 20s valleys) but will trend steady or
slowly rise overnight as clouds arrive and light southerly
return flow develops. An approaching warm frontal system will be
approaching from the south and west tonight and the leading
edge of its precipitation shield will begin to encroach into our
far western counties toward sunrise Friday in the form of light
A messy day then on tap for Friday as the warm front marches
into the region under strengthening southerly flow and
widespread mixed precipitation. Some channeling effects likely
in the Champlain Valley where gusts to near 30 mph look
plausible at this point. Boundary layer to mid level thermal
profiles will be critical in determining eventual p-type as
widespread light snows slowly transition to a mix of snow/sleet
and eventual rain from the Champlain Valley west. P-type should
hold more in the form of snow and/or a mix of snow/sleet across
much of east central and northeastern VT where mid level warming
will be less and colder near surface layers will be harder to
scour out. Mixed precipitation top down methodology using a
variety of model output continues to support the idea of little
in the way of freezing rain with this feature, which appears
reasonable seeing the primary mid-level warm layer generally
runs in the 0-3C range through 21Z. Experience would suggest
however at least some patchy -fzra may occur here and there
through the morning hours. Front end snow totals should
generally run in the 0.5 to 2 inch range, with slightly higher
totals from 1.5 to 4 inches likely across east central and
northeastern VT. Given the front end light snows will inhibit
any pavement icing and only low probabilities of a few
hundredths of ice accumulation are suggested (if any) will hold
off on issuing any advisories at this point. Late day high
temperatures should range from the lower to mid 30s east and
north, and the upper 30s to lower 40s elsewhere.
By Friday night widespread light rains (or mixed precipitation
north and east) will gradually wane over time as best warm
thermal advection lessens. Later at night models continue to
suggest building high pressure to our north will push the front
back southward into the area with flow transitioning to a light
northerly regime by daybreak Saturday. This will tend to shunt
the precipitation shield southward as well as coverage/intensity
lessens. Some lingering light rains/mixed precipitation/light
snows will remain possible though settle generally into our
southern counties by morning. Lows a bit tricky though with
expected abundance of clouds upper 20s to lower 30s looks
reasonable for most spots.
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 338 PM EDT Thursday....For Saturday and Saturday night
frontal boundary will remain draped across our forecast area.
This means that threat for mixed precipitation will continue
through the short term period. Large area of high pressure will
push South out of Canada on Saturday and push frontal boundary
south of our region. Precipitation will also push south of the
area and we will be in the cold sector on the North side of the
front. During the second half of Saturday night frontal boundary
lifts back up over the area and will be situated across
Northern New York and Vermont. Despite odd frontal boundary
drifting South of the area then back across our area the
temperatures Saturday and Saturday night will be very near to
seasonal normals. We will have a little bit of rain across our
Southern zones on Saturday, then some mixed precipitation as the
boundary lifts back northward Saturday night with some snow,
sleet, and freezing rain.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 346 PM EDT Thursday...Aforementioned frontal boundary
remains over Northern New York from Sunday through Monday. More
mixed precipitation is expected as thermal boundary is stacked
up right over us. Upper level low pressure system and strong
upper level shortwave cross the region later Sunday into Sunday
night, and still pushing Eastward across our CWA on Monday.
Precipitation will finally end Monday night. But, will only be a
short break in the action with another low pressure system
approaching for Tuesday into Wednesday. Unfortunately with
freezing lines staying very close to our forecast area, we will
mostly have rain with these systems but need to also continue to
monitor potential for trouble with mixed precipitation as well,
freezing rain and sleet. Tough to find a dry period over the
next week with very active weather and borderline temperatures
causing lots of forecasting challenges.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...VFR conditions prevail through 12Z before
an approaching warm front brings snow to the North Country. After
12Z Friday, snow will spread eastward reaching KMSS/KSLK around
12z...the Champlain Valley around 14Z and KMPV shortly after.
Snow will likely bring IFR/MVFR conditions before transitioning
to a snow/sleet/rain mix around 15-17Z over Northern NY, 16Z-18Z
in the Champlain Valley and at KMPV. Expect warming trend to
continue with wintry mix changing to rain during the afternoon.
Winds trending southerly 5 to 15 knots, most pronounced at
KBTV/KPBG where valley channeling effects may push gusts near 25
Outlook 00Z Saturday through Tuesday...
00Z Saturday through 18Z Saturday...MVFR/IFR conditions expected
to improve as precipitation settles southward and lessening in
coverage by Saturday afternoon affecting mainly southern
terminals at that point. Highest threat of mix to occur at
18Z Saturday through 12Z Sunday...trending mainly VFR
/precipitation-free as Canadian high pressure noses briefly
southward into the area.
12Z Sunday through 12Z Tuesday...widespread mixed precipitation
and/or rain return to the region.
12Z Tuesday onward...light and spotty mixed precipitation
transitions toward a period of steadier rains by Wednesday.