Scientific Forecaster Discussion
fxus61 kbtv 181440
Area forecast discussion
National Weather Service Burlington Vermont
940 am EST Thu Jan 18 2018
the north country will remain on the northern periphery of high
pressure today and Friday. Developing south to southwest winds
will bring about a gradual moderation in temperatures, but also
considerable low cloudiness associated with moisture from the
eastern Great Lakes. The clouds will be most prevalent across
the Adirondacks, St. Lawrence Valley, and far northern Vermont.
A few snow showers are possible tonight as a weak upper level
disturbance tracks from west to east across northern New York
into northern New England. Generally quiet weather is expected
over the weekend, and temperatures on Saturday are expected to
reach the lower 40s in many locations. A frontal system and
surface low pressure passing to our west Monday night into
Tuesday is expected to bring mixed wintry precipitation and a
period of plain rain to the region, before somewhat cooler
temperatures arrive for Wednesday.
Near term /through Friday/...
as of 940 am EST Thursday...increased pops through late
morning/early afternoon across the southern slv/dacks and into
portions of the Champlain Valley/central Vermont to account for weak
lake effect snow showers advecting east across these areas.
Models are not handling current light activity well, though most
recent hrrr output has a so-so handle on things showing modest
west-southwest transport flow of 20-30 kts at 925 mb so leaned in its
direction. Any acculumations will remain light and generally
less than 1 inch save perhaps areas to the west of kslk in
portions of far southern Franklin and St. Lawrence counties in
New York. The rest of the forecast regarding temperatures and general
cloud cover remain on track. Have a great day.
tonight: a quick-moving northern stream shortwave trough -
evident in infrared imagery across The Arrowhead of Minnesota - will
shift across nrn New York and nrn New England during the overnight
hours. Will see increased cloud cover areawide with a few snow
showers possible, especially across the nrn Adirondacks and nrn
greens, where a coating to 0.5" snowfall is possible. Mentioned
just a slight chance of snow showers in valley locations, with
limited moisture availability with this shortwave trough.
Overnight lows generally in the low- mid teens, except around
20f in the St. Lawrence Valley.
Friday: quiet and a bit milder, with valley highs 31-34f in most
areas. Continued swly low-level flow regime, so will continue to
deal with considerable stratus associated with moisture from the
ern Great Lakes. Daytime sfc winds generally S-SW 5-10 mph.
Short term /Friday night through Saturday/...
as of 329 am EST Thursday...rather quiet for the short term with
an upper level trough passing to the north of the County Warning Area Friday
night into Saturday. With that, just an increase in cloud cover
along the international border as well as a slight chance of a
snow shower, but not much else to speak of to start the weekend.
Winds still look to be gusty during the day as southerly flow
begins to pick up, but right now, it still looks to be sub-
advisory level. Temperatures will to trend upwards with warm air
advection with overnight lows in the 20s and upper teens in the
eastern Vermont counties. Saturday highs look to be in the low 40s
across the region.
Long term /Saturday night through Wednesday/...
as of 329 am EST Thursday...the second half of the weekend
continues to look to be quiet with slightly low high
temperatures for Sunday as flow shifts to the northwest. Outside
of a shower or two in the higher terrain, the weekend looks to
be pretty uneventful. This precedes a rather active early part
of next week as fairly deep low will move across the Great Lakes
and into Ontario sometime Tuesday.
Models continue to disagree on timing, with the GFS still running
about 12 hours ahead of the ECMWF, but the overall idea is the
same, a secondary surface low develops along a cold front and
rides up over our region on Tuesday into Tuesday evening. With
this secondary low, that means the warmer air at lower levels
will have a harder time of really coming in force and scouring
out the low level cold air. Both the GFS and European model (ecmwf) suggest a
widespread mixed precipitation event, with a general light snow
to start late on Monday, a good amount of sleet and perhaps
areas of freezing rain in the middle, and ending as snow later
Tuesday or Tuesday night. Have continued as the previous shift
did and used a mix of the warmer GFS and colder European model (ecmwf) to help
determine precipitation type. Still, this far out locking into
particular location for sleet/freezing rain is a bit premature
as the forecast will continue to change until we get closer to
the event. Still, on the bright side, with this looking to be
much cooler than last week's event, Hydro looks to be less of a
concern but still bears monitoring.
Beyond this system, Wednesday and beyond look rather quiet,
though a snow shower or two are not out of the question. Look
for highs in the long term in the 30s with Tuesday touching the
lower 40s in the valleys and overnight lows in the 20s to teens.
Aviation /15z Thursday through Monday/...
through 12z Friday...latest infrared satellite imagery shows stratus
deck stretching from Lake Ontario ewd across much of nrn New York and
far nrn Vermont. Should see persistent MVFR ceilings today at
btv/pbg/mss with occasionally lower (ifr) ceilings at slk with
wswly upslope flow conditions. Hir terrain obscd, and may see
occasional flurries. Periods of snow showers possible at slk
with vsby below 3sm possible. Winds generally expected S-SW
throughout the taf period at 5-10kts. Some valley channeled flow
vcnty of kmss will yield slightly higher wind speeds, generally
10-15kts. A modest northern stream shortwave trough may bring a
few passing snow showers tonight across the region. Coverage
generally expected to be limited, and have only carried vcsh
group at kslk after 02z attm.
Friday: mainly VFR, with areas MVFR possible. No sig weather.
Friday night: mainly VFR, with local MVFR possible. Slight chance
Saturday: mainly VFR, with local MVFR possible. No sig weather.
Saturday night: mainly MVFR, with areas VFR possible. Slight
Sunday: mainly MVFR, with local IFR possible. Slight chance shra,
slight chance shsn.
Sunday night: mainly VFR, with areas MVFR possible. Slight chance
Monday: mainly MVFR, with areas VFR possible. Chance sn, likely
fzra, chance ra, chance shsn.