Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 190327
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1027 PM EST Wed Jan 18 2017

.SYNOPSIS...
Plenty of clouds will persist over the area tonight through
Friday. Some light precipitation is also possible tonight into
the first part of Thursday, mainly some light rain or light
snow...but there may also be some light freezing drizzle across
part of northern New York and northern Vermont. The clouds will
also keep above normal temperatures over the region through
Friday as well.

&&

.NEAR TERM /UNTIL 6 PM THURSDAY EVENING/...
As of 1007 PM EST Wednesday...Plenty of low-level moisture in
place across the North Country late this evening. Overcast skies
will continue to prevail (stratus layer), with intermittent very
light drizzle/freezing drizzle and areas of mist/fog. The
relatively mild temperatures and dewpoints by mid-January
standards (low- mid 30s) over the fresh snowpack should also
enhance the potential for fog overnight. Temperatures will fall
very little from current readings, with lows generally in the
upper 20s to lower 30s. Expecting a low right around 32-33F at
BTV early Thursday morning. Wind speeds have been gradually
lessening this evening as high pressure builds ewd across
wrn/central NY state. S-SW winds generally diminish to 5 mph or
less after midnight, and gradually become W-NW during the day
Thursday.

There is a mid-upper level shortwave trough, evident on IR
imagery tracking sewd from swrn Quebec and sern Ontario. This
feature will provide some additional mid-level moisture, and
potential seeder-feeder processes w/ lower stratus deck may
yield some light snow shower activity, in addition to the
patchy drizzle/freezing drizzle. Any snow accumulations would be
less than an inch. Ice amounts associated with any freezing
drizzle generally not expected to be measurable (<0.01"), and
thus not expecting any significant travel impacts for the
overnight hours.

On Thursday, looking at plenty of cloud cover all day and with
upper ridge building in, low-level inversion strengthens to
keep moisture/clouds and some fog in over the area. As will be
the case tonight...warmer air over fresh snowpack will also help
enhance the potential for low clouds and fog over the area.
Will keep the idea of areas of fog going for Thursday with highs
in the 30s to around 40. In addition...areas over northern
Vermont may have a little light snow early...but ice goes away
in the clouds and some light freezing drizzle may occur in this
area as well. Drier air finally moves in during the afternoon
hours on Thursday.

&&

.SHORT TERM /6 PM THURSDAY EVENING THROUGH FRIDAY NIGHT/...
As of 255 PM EST Wednesday...Large scale synoptic pattern shows
mid/upper level ridge directly overhead with building 1020mb
surface high pres. This results in a steepening subsidence
inversion with very light winds through the vertical profile and
plenty of low level moisture trapped below thermal inversion.
Forecast challenge will be determining if depth of moisture is
enough to produce areas of patchy drizzle/freezing
drizzle...especially Thursday Night...followed by any potential
clearing on Friday Afternoon.

Based on sounding profiles and available moisture thinking any
drizzle/freezing drizzle would occur above 1500 feet mainly Thursday
Night and again on Friday Night. Overall areal coverage will be
limited along with impacts...as temperatures will be holding in the
upper 20s to mid 30s for lows during this time period. Daytime
temperatures on Friday will be tricky with sharp
inversion...supporting higher temps in the mid/upper slopes and
cooler values in the deeper valleys like the CT River
Valley...Champlain and Saint Lawrence Valleys. Highs mainly in the
mid 30s deeper valleys to lower 40s, very difficult to place this
detail into the grids. Based on moisture depth of 2000 to 3000
feet...would not be surprised if summits breakout on Friday
Afternoon. Have continued with previous forecasters idea of trying
to show summits in the clear on Friday Afternoon.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 255 PM EST Wednesday...Pattern becomes more active by early next
week with large scale system expected to impact our forecast area.
Still plenty of uncertainty on impacts...timing...and thermal
profiles.

On Saturday...weak 5h vort and thin ribbon of dissipating mid/upper
level moisture tries to break down mid/upper level ridge across the
NE CONUS. Expecting very little fan fair associated with this
energy/moisture...as ridge holds in place. Increasing moisture
profiles may produce some very light rain or snow on Saturday with
temps mainly in the mid 30s to lower 40s.

Potent energy moving into CA on Fri/Sat will quickly eject into the
southern Plains by Sunday with a developing and closing off deep
full latitude trof taking shape across the eastern CONUS. This
system will have plenty of moisture from the pacific sub-tropical
jet and moisture advection from the Gulf of Mexico as pws climb
between 0.75 and 1.50 inches. A deep south flow aloft and strong
925mb to 850mb flow from the southeast will help to advect this
moisture into our region on Monday into Tuesday as surface low pres
is located over the mid Atlantic States. Have noted the nose of a 50
to 60 knot southeast 850mb jet angling into our region...resulting
in lots of downslope shadowing in the precip fields across the
western slopes/northeast Kingdom associated with this system. The
potential for gusty southeast downslope winds will need to be
watched...along with how much warm air can be advected into our
region. Given placement of 1030mb high pres over eastern
Canada...some low level cold air will linger to support a
snow/sleet/freezing rain threat initially...but this area of high
pres is not very cold...so threat is minimal at this time. Next
threat with warmer temps and rain...will be to watch area waterway
for potential rises and ice jams...all elements to monitor as we
move closer to this system. My initial thoughts are lots of items to
watch...with some potential impacts...stay tuned.

Thermal profiles continue to support much above normal temps through
the period...especially overnight lows. Over the weekend progged
925mb to 850mb thermal profiles hover around 0c...with limited
mixing supporting highs mainly in the mid 30s to l/m 40s. Lows with
clouds will hold mainly in the upper 20s to mid 30s...but if more
clearing develops than anticipated much cooler values can be
expected...especially in snow pack mountain valleys on Sunday Night.
early next week...highs continue to be in the 30s to near 40f with
lows mainly in the mid 30s.

&&

.AVIATION /03Z Thursday THROUGH Monday/...
Through 00Z Friday...Overcast skies will prevail thru the
period, but looking at a wide variety of flight categories.
Generally IFR ceilings at MSS/SLK, and MVFR-VFR elsewhere with
ceiling heights generally 2-4kt. HIR TRRN OBSCD. Could see a few
brief snow showers, or intermittent/patchy drizzle/freezing
drizzle from the low cloud deck. Also looking for some
occasional vsby restrictions due to patchy BR, generally in
3-5sm range. Surface winds generally south to SW 5-9kt, trending
light and variable after 03Z. With high pressure building in
during the day Thursday, will maintain light and variable wind
conditions during the daylight hrs Thursday.

00z Friday - 18z Friday - dry weather is expected but the
potential for low clouds and fog creating MVFR and IFR
conditions will exist during this period, with HIR TRRN OBSCD.

18z Friday through Monday - VFR conditions are expected through
the period.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Evenson
NEAR TERM...Banacos
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Banacos/Evenson



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