Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 211310
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
910 AM EDT Tue Mar 21 2017

.SYNOPSIS...
A weak upper level trough will move eastward across the North
Country today, resulting in considerable cloudiness and a few
rain or snow showers. An arctic front follows tonight, bringing
a period of late evening snow showers or localized snow squalls,
followed by gusty northwest winds and much colder temperatures.
Highs on Wednesday will only reach the upper teens to lower 20s
across northern New York and Vermont. A strong area of surface
high pressure builds in for Thursday, with lighter winds and a
moderating temperature trend. A warm front approaching from the
southwest will bring a chance for mixed wintry precipitation on
Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 910 AM EDT Tuesday...Massaged pops upward slightly across
northern counties through early afternoon per latest
observational trends. Mainly scattered light snow and/or mixed
snow/rain showers in these areas but little accumulation
expected in the valleys where boundary layer warming will
continue. Forecast max temperatures remain on track for upper
30s to lower 40s for most. Have a nice day.

Prior discussion...
Strong arctic frontal passage will occur tonight. It appears the
front will race through KMSS at 02Z and through BTV by 04Z,
before exiting south and east of VT around 06Z. Still seeing
some indications of possible snow shower or snow squall activity
associated with sharp low-level convergence along the frontal
zone. Steep low-level lapse rates contribute to SBCAPE up to 100
j/kg per 00z NAM, and there is an axis of strong 925mb
frontogenesis forcing along the boundary as well. SNSQ
parameter values reach 3-6 units per 00Z NAM. PBL temps will
likely be slightly above freezing as the front moves thru, at
least in valley locations. So, anticipate potential for briefly
moderate snowfall (vsby near 0.5sm) and some of that snow to
initially melt on paved surfaces with road temps above freezing.
However, the strong CAA that follows (lows single digits to
lower teens) will result in some icy spots on the roadways with
the temp drop, and will be something that we`ll need to closely
monitor following FROPA from a travel perspective. Anything
along the lines outlined above can be handled with a Special
Weather Statement as conditions unfold, but will make brief
mention in the Hazardous Weather Outlook as well.

Wednesday will be a cold day with N-NW winds 15-25 mph and some
gusts up to 35 mph with steep low-level lapse rates and 850mb
temps falling to near -24C at 18Z/Wed. Highs on Wednesday will
only range from the upr teens to lower 20s, with wind chill
readings 5 to 15 below in the early morning, and 5 above to 5
below during the afternoon hrs. May continue to see some
mountain snow flurries through the first half of the day.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 335 AM EDT Tuesday....Winter`s final charge should be in
full force as an arctic airmass will be in place over the region
on Wednesday night. Expect the coldest temperatures of the week
to be Wednesday evening as the high pressure crests overhead.
Excellent radiational cooling will see temps drop into the
single digits over the North Country with the near lake areas a
few degrees warmer in the low teens.

High pressure continues during the day on Thursday with quiet
weather conditions expected. The dry air aloft should mean that
we should see some mostly clear to partly cloudy skies with
below normal temps in the 20s. The cold air starts to exit the
region Thursday night as the high pressure dives south towards
the DelMarVa peninsula. We should see overnight lows in the
single digits for Vermont while the warm air starts creeping
back in over Northern New York. Lows across the Saint Lawrence
should be in the lower 20s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 335 AM EDT Tuesday...The models have come in slightly
better agreement for a Friday solution. The departing high
pressure dives south however the upper level ridge amplifies.
The result is that the northern stream disturbance has weakened
and a warm front never reaches the North Country. Two things
here, one, that means we`d be looking at some sort of a mixed
bag with regards to precip and two, as the ridge amplifies the
whole system could end up south of the area and the northern
tier of counties see little to no precip at all. Given its
still 72 hours out I dont have great confidence in what
situation plays out. So I`ve opted just continue the mention of
rain changing over to snow at some point over the weekend.
Coming out of the weekend, there will be another cutoff upper
level system that could bring additional mixed precipitation
type concerns as a warm nose creeps up the Saint Lawrence.

Overall temperature trends are that the general source air
becomes more Pacific than arctic and so temp should be on the
rise back to near normal for late March.

&&

.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
Through 12Z Wednesday...Weak mid-level wave bringing BKN-OVC
MVFR-VFR ceilings to the region today, with periods of MVFR
already occurring at SLK and BTV, along with HIR TRRN OBSCD.
May see a few flurries or sprinkles later this morning, and
ceilings may briefly fall into the MVFR range at most TAF
locations late this morning before improving some this
afternoon. Arctic frontal passage occurs around 02Z/Wed at KMSS
and 04Z/Wed at BTV. Should see a brief period of IFR conditions
associated with snow showers and squalls along the front, with
moderate snow possible for 15-30 minute period. May see a
"flash freeze" situation with snow initially melting on warm
surfaces, but quickly freezing as temps drop rapidly overnight
Tuesday night. This may be an issue for airport ground ops.
Winds light during the day, but becoming NW 15-20kt with gusts
25-28kt following frontal passage tonight.

12Z Wednesday through Saturday...
Returning to VFR Wednesday with flurries confined to the mtns.
VFR Thursday with strong high pres in place and lighter winds.
Warm/stationary front brings possible MVFR conditions with mixed
wintry precipitation possible Friday/Saturday.

&&

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

&&

$$
SYNOPSIS...Banacos
NEAR TERM...JMG/Banacos
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Banacos


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