Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 141432
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
932 AM EST Thu Dec 14 2017

.SYNOPSIS...
Cold temperatures are here and will remain through the weekend.
There is a chance for some light snow showers Friday night into
Saturday. Temperatures will moderate next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 932 AM EST Thursday...Forecast for today remains in
excellent shape with only minor changes needed to blend hourly
temperatures with the latest observations.

Previous Discussion...Dry and cold weather will be the
main story for today through Friday with cold surface high
pressure ridge over us. Maximum temperatures will top out in the
single digits and teens today which is about 15 to 20 degrees
below seasonal normals. Our region is under a very cold airmass,
the coldest of this meteorological winter season so far. 850
temperatures will dip to about -20 C this afternoon. Although it
will be a cold day, winds will be generally light and will see
some sunny skies this afternoon so not a terrible day. As
previous forecaster mentioned...atop the high peaks, temps will
barely touch zero, and winds will be brisk in the 20-30 mph
range, wind chills will push into the -20 to -30 below zero
range.

Tonight will be cold as well though the air mass will slowly be
warming for tonight and Friday. Another weak low pressure system
approaches the area Friday, and the flow ahead of this low will
become favorable briefly for some lake effect snow showers in
extreme southern Saint Lawrence county. Temperatures Fri will be
a bit warmer but still colder than seasonal normals, generally
teens to lower 20s with increasing cloud cover through the day.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 405 AM EST Thursday...A weak shortwave clipper system
will be tracking through the Great Lakes which will bring some
warmer air initially through the evening hours for most of the
north country. The track of the surface low looks to track from
Lake Huron southeast through Lake Ontario. This should lead to a
long southwesterly fetch and resulting lake effect snow event
off Lake Ontario. Based on the NAM and CMC it looks like the
snow should only impact Saint Lawrence county for a 6-9 hour
window. BUFkit soundings indicated the lake induced CAPE should
be in the 400-500 J/kg based on a lake temp of 42F and 850mb
temp of -11C. The issue preventing me from going with large snow
totals just yet is the short window and the high shear during
the event. So I`ve gone with a general 3-4" generally up the
Saint Lawrence river and between 1-3" as the band drifts to the
south. We`ll also need to continue to watch for the potential
for snow squalls across Northern New York on Saturday as the
925mb thermal gradient is quite sharp and the Snow Squall
parameter is indicated the potential for some squalls generally
over the Adirondacks based on a local 4km WRF model.

As the 700mb trough enters the region it will shut off the lake
effect snow by mid day on Saturday and usher in a return of
colder temps. Expect lows during the warm advection on Friday
night in the teens and after the front Saturday lows Saturday
night will be in the low single digits.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 415 AM EST Thursday....Sunday and Sunday night should be
fairly quiet with ridging at the surface and zonal flow aloft.
There still seems to be some inconsistencies with what happens
coming out of the weekend. The GFS still points to a null event
but the CMC and EC show a weak shortwave bringing a reinforcing
shot of warm advection snow to the region. QPF totals aren`t
really on the high side but nonetheless there should be some
accumulating snow Monday during the morning and into the
afternoon.

Temperatures will be the more challenging issue as we`ll see a
moderating trend with highs in the valleys in the mid 30s on
Monday and near 40 on Tuesday. So the natural issue with warming
temps will be p-type concerns on Tuesday. At this time given
the amount of variability, and how a degree or two makes the
difference between rain/sleet/snow, I`ve just left mention of
rain/snow based on the boundary layer averaged temp for Tuesday
morning. By Wednesday the front from the system should be
through the region and we return to near normal temps with highs
in the upper 20s to low 30s in the valleys.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Through 12Z Thursday...VFR conditions continue for the 24 hr
TAF period. Some mid and high level clouds will move across the
area...but have little impact. Winds will be a bit gusty at BTV
and PBG this afternoon around 20 kts.

Outlook...

Friday: VFR. Chance SHSN.
Friday Night: Mainly VFR, with local MVFR possible. Chance SHSN.
Saturday: Mainly VFR, with areas MVFR possible. Chance SHSN.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Slight chance SHSN.
Sunday Night: VFR. Chance SHSN.
Monday: Mainly MVFR, with local VFR possible. Chance SHSN.

&&

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

&&

$$
SYNOPSIS...Neiles
NEAR TERM...Lahiff/Neiles
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Neiles



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