FXUS61 KBTV 201356
Area Forecast Discussion
National Weather Service Burlington VT
956 AM EDT Sat Oct 20 2018
A changeable weather pattern is expected this weekend, as a
series of cold fronts impact the North Country. Temperatures
will be near normal today, but trend back below normal for
Sunday into early this upcoming week. Each front will be
accompanied by a chance of rain showers and mountains snow
showers, along with periods of breezy conditions. The overall
coverage of precipitation will become mainly terrain focused on
Sunday, before cold high pressure builds into the region by
Monday. Additional precipitation chances occur toward midweek
with below normal temperatures prevailing.
.NEAR TERM /THROUGH SUNDAY/...
As of 956 AM EDT Saturday...Only minor tweaks made to the
current forecast to lower precipitation chances for the next
couple hours...current radar trends indicate that precipitation
has tapered off a little more quickly across Northern NY than
originally anticipated. Otherwise, forecast remains in good
shape with chances remaining, primarily across the high terrain,
for scattered showers throughout the day as a series of fronts
pass through the area.
Previous Discussion...Minor change to expand pops across
northern NY and increase to near 100% for the next 1 to 2 hours.
Radar and obs show light rain with embedded moderate rain
showers impacting slv/western dacks. Expect this activity to
decrease in areal coverage/intensity as area approaches the cpv
by 12z. Best chance of a shower or two would be across the
higher trrn of northern VT near Jay Peak this morning.
Otherwise, developing dry slot will decrease rainfall with areas
of clouds and sun expected from mid-morning to mid afternoon.
This along with good mixing will help to warm temps into the
upper 40s to upper 50s, even with cooling profiles aloft.
Changeable weather anticipated the next 12 to 24 hours as a
series of s/w`s and cold fronts swing across our fa. Water vapor
shows potent 5h vort approaching the slv, but best deep layer
moisture is suppressed to our south...as pw analysis shows
values near 0.60. These quickly drop to 0.30 as well defined
mid/upper level dry slot across the central Great Lakes advects
across our cwa today. Thinking current band of rain showers will
slowly fall apart across the slv/dacks this morning, as s/w
energy weakens and best moisture is continued to be suppressed
to our south. Have mentioned likely pops west and taper to
schc/chc pops further east, with highest qpf amounts of 0.10 to
0.20 across the slv. Given breezy southwest winds of 35 to 45
knots, thinking downslope shadowing will occur across the cpv
with minimal precip expected. Clouds coverage will be tricky
today, with a little of everything possible, especially in the
cpv. Thinking mostly cloudy skies prevail in the mountains.
Temps will range from near 40f summits to mid/upper 50s warmer
valleys, with summit temps falling back into the upper 20s and
lower 30s by 21z today, as 850mb caa develops. Secondary front
surges across our cwa this evening and helps push 925mb temps
below 0c by 06z. This secondary front is associated with some
mid level moisture, but best forcing associated with 5h energy
passes to our south, so any precip will be light and mainly trrn
focused in northern dacks and mountains of Vt. Have continued
to mention chc pops with thermal profiles supporting snow levels
down to 1500 feet by morning, with very limited accumulation
anticipated. Maybe a dusting to 0.5 above 2000 feet in the
northern dacks and parts of the green mtns. Lows range from the
upper teens summits to mid/upper 30s cpv and lower ct river
valley tonight. A cold and breezy day is anticipated on Sunday
with moderate low level cold air advection prevailing. 850mb
temps are a degree or two warmer than previous cold spell, with
values near -9c or -10c, so have highs mainly lower/mid 20s
summits to l/m 40s warmest valleys. Soundings support northwest
winds 15 to 25 knots with localized gusts up to 30 knots
possible in favorable northwest downslope aligned valleys.
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
As of 415 AM EDT Saturday...Sunday night will be cold with
temperatures dropping below freezing areawide. Temperatures will
generally be in the 20s, with some teens in the coldest spots.
It will be warmest along the shores of Lake Champlain. Surface
high pressure ridge will be building into our region from the
South. 850 temps will be around -10 C. These temperatures will
be almost 10 degrees below seasonal normals for the second half
of October in Northern New York and Vermont. On Monday high
pressure ridge will slide eastward and Southwesterly flow will
develop. With that we may see some lake effect snow showers
making it into the Southern St Lawrence Valley and Adirondacks.
Progressive upper level flow will be in place and will have
several upper level shortwaves passing overhead. Monday high
temperatures will also be below seasonal normals, generally mid
30s to mid 40s with some colder spots in the higher elevations.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 415 AM EDT Saturday...On Monday night into Tuesday an
upper level shortwave trough will be approaching from the west
and we`ll have our next chance of precipitation. There`s a weak
surface low associated with this upper level feature, not a lot
of forcing so don`t expect any significant precipitation. This
upper level trough will be very slow moving, and finally move
east of our region on Thursday. Thursday through Saturday then
looks drier with surface high pressure building into the area.
Temperature will remain below normal through the extended
portion of the forecast with highs in the 40s and lows in the
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Through 12Z Sunday...Aviation impacts will be winds today,
followed by lower cigs at slk/mss. Radar shows a band of light
to moderate rain impacts our western taf sites this morning.
Expect showers to linger thru 15z before dissipating as dry slot
develops. Soundings show lowering cigs this morning at slk
associated with breezy southwest flow at 35 to 45 knots, helping
to transport lake enhanced moisture. This setup will produce
mvfr cigs at slk, with potential for brief period of ifr btwn
13-16z this morning. Elsewhere, downslope southwest flow will
keep cigs at vfr levels at pbg/btv. Some localized mvfr possible
at rut/mpv. Breezy southwest winds 20 to 30 knots this morning
will shift to the west/northwest this aftn/evening at 10 to 20
with localized gusts up to 25 knots. Nw upslope flow will help
to redevelop mvfr cigs at slk/mpv overnight tonight.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. Slight chance SHRA.
Monday Night: Mainly VFR, with local MVFR possible. Chance SHRA,
Tuesday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Tuesday Night: MVFR/IFR conditions possible. Chance SHRA, Chance
Wednesday: Mainly MVFR, with local IFR possible. Chance SHRA.
A Lake Wind Advisory will continue today with south winds
generally remaining in the 20-30kt range. A cold front will
sweep across Lake Champlain during the mid-day hours, resulting
in a westerly wind shift by this afternoon, with winds
decreasing slightly into the 10-20kt range behind the cold
front. Waves will be 2 to 4 ft.