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fxus61 kbtv 151115 
afdbtv

Area forecast discussion
National Weather Service Burlington Vermont
615 am EST Fri Nov 15 2019

Synopsis...
warmer temperatures are in store for the north country today with
highs in the lower to upper 30s. These warmer temperatures will be
short-lived with a strong Arctic cold front expected to move through
the region this afternoon and evening. Convective snow showers and
snow squalls are expected to move across northern New York and
northern Vermont during the evening commute. These squalls will
produce white-out conditions and could create very slick Road
surfaces as temperatures plummet quickly after the front moves through.
Record breaking cold temperatures are then expected tonight and
again on Saturday night with temperatures beginning to moderate as
we head into the beginning of next week.

&&

Near term /through Saturday/...
as of 319 am EST Friday...persistent southwesterly flow across
Eastern Lake Ontario has caused a weak lake effect band of snowfall
to develop across the St. Lawrence Valley this morning. This has
brought snow showers to Massena and Ogdensburg with little in terms
of accumulations thus far. As winds begin to shift more westerly
during the mid to late morning hours, the snow band will shift
further east into northern New York and bring chances for snow
showers to Essex, Franklin and Clinton counties in New York.
Temperatures today will be on the mild side when compared to recent
days with highs in the lower to upper 30s (still 7-10 degrees below
normal). High temperatures today will likely be achieved by early
afternoon as a strong Arctic cold front will quickly descend across
the north country.

Speaking of the strong Arctic cold front, everything remains on
track for the development of snow squalls this afternoon across
northern New York and the northern half of Vermont. All of the
ingredients remain present and more impressive than they did
yesterday: a strong Arctic cold front, instability ranging from 75
to 150 j/kg of cape, strong frontogenetic forcing due to the strong
temperature gradient along the front and moisture pooling out ahead
of the cold front. Looking at the latest high-res guidance, it looks
like snow squalls could form as early as 3 PM in Massena and move
into the Saranac Lake, Burlington and St. Albans area around 5 PM.
Given the latest timing, these squalls will likely impact the
evening commute across northern New York and northern Vermont. All
commuters are urged to keep an eye on the skies and be ready for
rapidly deteriorating conditions as the squalls push through the
region. Snowfall amounts won't be overly problematic with most
places seeing less than an inch of snowfall. However, the fact that
many places will be above freezing this afternoon is a bit
concerning as roads will likely be wet from melting snow.
Temperatures behind the Arctic cold front will drop very quickly
which could create a flash freeze on roadways that aren't treated
which could lead to very slick travel conditions.

Skies will quickly clear tonight following the passage of the cold
front with a plethora of dry air moving into the region. When you
couple the clearing skies with very strong cold air advection behind
the front, you get a favorable set-up for radiational cooling. Given
that both the 850 mb temps and 500 mb temps are in the 99th
percentile for below average values, this is no Ordinary cool down.
In addition, hysplit backward trajectory models show this air mass
originated at the North Pole. Near record to record low temperatures
are expected tonight and again Saturday night while we could see
record low high temperatures on Saturday. Bundle up folks, another
record breaking cold snap is on the way.

&&

Short term /Saturday night through Sunday/...
as of 319 am EST Friday...bitter, potentially record-breaking cold is
expected Saturday night/Sunday morning as high pressure crests
directly overhead. With light winds, clear skies, and a relatively
fresh snowpack, radiational cooling will be optimized, allowing
temperatures to drop dramatically overnight. Have trended a bit
downward from the previous forecast, closer to MOS guidance, which
is going quite cold (ie met says -11f at slk). Have gone with single
digits above zero in the wider valleys, and zero to a few degrees
below in the mountains. Later shifts will need to monitor trends and
make adjustments as needed.

For Sunday...the high shifts east and warm advection starts with the
flow turning to the south/southeast. Hence expect temperatures will
rebound nicely, eventually topping out in the upper 20s north to mid
30s south. May see an increase in mid and high clouds through the
day, but overall expect sunshine and dry conditions.

&&

Long term /Sunday night through Thursday/...
as of 319 am EST Friday...turning warmer (but still cooler than
normal) through next week. It'll be unsettled as well with chances
for precip for much of the period. First will come an upper
shortwave and associated surface low, which will traverse up along
the East Coast, remaining east of the benchmark. Timing/placement of
the northern fringe of the precip associated with this system's warm
air advection is in question; the NAM spreads a decent slug
northward into the north country Sunday night into Monday, while the
GFS and European model (ecmwf) are slower, holding any precip off until daytime
Monday. Given the cold, dry air that will be in place, feel that
it'll take a while for the column to saturate; have therefore leaned
toward the slower guidance and kept Sunday night mostly dry.
Regardless, precip type will be a concern with the aforementioned
cold air locked in at the surface. Meanwhile, warm air moves in
aloft, though the extent of the warm nose differs between model
solutions. Still, expect precip would start out as a wintry mix,
especially if the earlier NAM solution is correct. The precip may
mix with or change over to rain for a time Monday afternoon into the
evening. Things will then change back over to snow Tuesday as the
low shifts east and colder air follows in its wake. Thereafter,
another upper trough digs into the Great Lakes, forming a closed low
which will move over or just south of our region Tuesday night
through Wednesday. Brief ridging follows Wednesday night, but
another upper trough approaches from the west to end the week. Given
all this, have a lot of chances of precip, mainly rain and snow, for
mid to late week.

&&

Aviation /11z Friday through Tuesday/...
through 12z Saturday...a weak band of snow showers has set up
over the St. Lawrence Valley and should continue through about
15z or so which could produce some brief periods of low MVFR at
kmss. Otherwise, sites are generally VFR this morning with
winds from the south at 10 to 17 knots. We will see winds
gradually shift to the southwest during the morning hours while
increasingly in magnitude ahead of a strong cold front. This
cold front will bring strong convective snow showers and snow
squalls to much of the north country late this afternoon and
early evening hours with kmss seeing near whiteout conditions
around 20z and Burlington closer to 22z. These showers will
weaken as they track west to east but there will be some strong
gusty winds coupled with brief heavy snow as these squalls move
through. Following the front, we will see winds quickly shift to
the northwest with sustained winds in the 15 to 18 knot range
and gusts around 25 knots continuing into the early evening
hours. Following the front, we will see skies quickly clear
leading to VFR conditions at all terminals by the end of the
forecast period.

Outlook...

Saturday: VFR. No sig weather.
Saturday night: VFR. No sig weather.
Sunday: VFR. No sig weather.
Sunday night: mainly VFR, with local MVFR possible. Slight chance
freezing rain.
Monday: mainly VFR, with areas MVFR possible. Chance fzra, chance
ra, slight chance pl.
Monday night: MVFR/IFR conditions possible. Chance pl, chance
fzra, chance snow.
Tuesday: mainly MVFR, with areas IFR possible. Chance ra, chance
snow.

&&

Climate...
here are some min and low Max temperature records which could be broken over
the next few days.

Min temp records
datekbtv kmpv k1v4 kmss kpbg kslk
11-16 6|1967 4|1967 10|2003 0|1967 11|1967 -11|1933
11-17 7|1924 5|1972 20|2017 12|1980 14|1972 -10|1933

Low Max temp records
datekbtv kmpv k1v4 kmss kpbg kslk
11-16 22|1933 22|1967 31|2018 20|1967 29|1967 16|1933

&&

Btv watches/warnings/advisories...
Vermont...none.
New York...none.

&&

$$
Synopsis...Clay

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