Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
922 PM EST Sat Jan 24 2015
an Arctic cold front will pass through the region this evening
associated with a Canadian low pressure system passing well to
the north. A coastal low pressure system will provide some
lingering snow showers over southern Vermont. Cold air advection
ahead of a potential strong system early next week will bring cold
overnight lows and daytime highs through next week. A potentially
strong system will bring widespread snow showers to the area
Tuesday into Wednesday next week.
Near term /until 7 am Sunday morning/...
as of 922 PM EST Saturday...regional radar as of 9 PM reveals
batch of scattered to numerous snow showers largely skirting
across northern New York and the northern half of Vermont, ahead
of an approaching Arctic front. Occasional periods of snow showers
will continue across this general area up until the frontal
passage. I've had to adjust probability of precipitation a little bit over the next couple
of hours to account for ongoing snow showers, but have maintained
areal coverage wording for the overnight. Light snowfall
accumulations of d-2" still look good. Frontal timing still
appears to be on track, expected after midnight into the St.
Lawrence Valley, toward the pre-dawn hours into the Champlain
Valley and early morning for the rest of Vermont. Expect a rapid
temperature fall behind the front as temperatures fall into the
single digits to the teens north and the upper teens/low 20s south
(with sharper temperature falls anticipated into Sunday morning
for southern vermont).
Short term /7 am Sunday morning through Tuesday night/...
as of 342 PM EST Saturday...Sunday morning an upper level ridge
will build into the region and surface high pressure will move in
rapidly from the west. This will continue the surge of cold air
and leave the area looking at maximum temperatures in the middle to low teens on
Sunday with dry weather and partly cloudy skies. Monday the broad
surface high will be firmly entrenched over the region so Monday
will be another quite cold day under mostly clear skies and light
and variable surface winds under southwest flow aloft.
By Monday night a deepening upper level trough over the Great
Lakes will combine with a developing coastal surface low pressure
system and have the potential to be a strong coastal storm off the
New England coast by Tuesday morning. There is very good
consensus among medium ranged models that the system will develop
and track just off the New England coast which means that
widespread precipitation looks likely for most of the area where some of
the precipitation will fall as snow. At this point with the variable
nature of the track and the fact that as of yesterday the ecwmf
was the only long range model with the system i've been hesitant
to add in fine scale details to the forecast concerning snowfall
accumulation on the leading edge of the system Monday night.
Long term /Wednesday through Saturday/...
as of 341 PM EST Saturday...quite a change from 24 hours ago...as
European model (ecmwf)...GFS and Canadian models show a low pressure area bombing
out south of New England on Tuesday. Models spread snow further
west into Vermont and into northern New York on Tuesday.
However...models differ as to the track of this low. European model (ecmwf) appears
to be the outlier on Tuesday as it has the low west-southwest of
the benchmark at 18z Tuesday...while the other models are east-
northeast of the benchmark by 18z Tuesday. Snow amounts at this
time are still uncertain...given differences in the track of the
low. Have opted to go higher than the super-blend probability of precipitation on Tuesday
and have gone with likely probability of precipitation across all of Vermont and the
Champlain Valley...and chance probability of precipitation across the Adirondacks and
Saint Lawrence valley in northern New York.
Models show snow winding down Tuesday night as low starts to move
northeast toward Nova Scotia. However...have still gone higher
than super-blend probability of precipitation for Tuesday night.
High pressure to build into the region Wednesday and Wednesday
night. A clipper system will move east-southeast from the upper
Mississippi Valley and will be off the southern New England coast
on Friday. Thus...have gone with chance probability of precipitation for snow from
Thursday through Friday. Another shot of Arctic air will move into
the region Friday night and Saturday. High pressure will build
southeast from the Great Lakes on Saturday...with fair and dry
Aviation /02z Sunday through Thursday/...
through 00z Monday...a cold front approaching from southeastern Ontario
will bring scattered flurries through the first half of
tonight...and then periods of MVFR-IFR snow showers 06-12z. Only
minor impacts to aviation ground operations anticipated...with
snow accumulation at the taf sites generally less than 1 inch.
Surface winds generally light W-NW...then increasing to 10-15 kts
with gusts to 25 kts toward daybreak and through much of the day
Sunday with steep lapse rates and strong p-gradient behind the
front. Skies generally clear late morning Sunday with a return to
Outlook 00z Monday through Thursday...
00z Monday through 12z Tuesday...generally VFR with high
12z Tuesday through 12z Wednesday...IFR/MVFR in snow from
deepening storm off the New England coast.
12z Wednesday through 18z Thursday...mainly VFR conditions
expecting as ridge of high pressure builds into the region.
18z Thursday through 00z Friday...developing IFR/MVFR in light
as of 106 PM EST Friday...the ktyx 88d Doppler radar located in
northern New York will be down at least through Monday January
26th. This is due to a pedestal dynamic fault. An electronics
technician has ordered new parts to fix this problem.
However...the new parts have not arrived as of this time and the
ktyx radar will likely not be restored to service until early next