Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kbtv 171502 

Area forecast discussion
National Weather Service Burlington Vermont
1002 am EST Tue Jan 17 2017

low pressure will move northeast through the eastern Great Lakes
today and up the St. Lawrence Valley tonight and Wednesday. A mix of
wintry precipitation will begin in northern New York late this
afternoon, and spread east across Vermont tonight, and continue
area-wide through Wednesday. Be ready for slow travel
conditions tonight and for the morning commute on Wednesday.


Near term /through Wednesday/...
as of 1002 am EST Tuesday...satellite loop showing mainly high
clouds over most of the region at this time. Expecting cloud
cover to be on the increase for the remainder of today. 06z GFS
model run showing bulk of precipitation will not move into the
region until very late this afternoon and early this evening.
Have lowered pops a bit for today, due to the slow movement of
precipitation moving into the region, as it will take a while to
saturate the lower portion of the atmosphere due to the dry air
that has been over the region. Expecting partly sunny skies for
most of the remainder of the daylight hours today.

Previous discussion from 621 am EST changes to
this first part of the forecast, so far tracking along well.
Temperatures in the teens and lower 20s, with clear skies. Kmss
reporting 6sm br but otherwise no other obstructions to
visibility. A quiet first half of the day as the surface ridge
shifts east ahead of our next approaching storm system. Light
east to southeast low level flow ahead of the low, with
increasing clouds already seen approaching on infrared satellite. High
temps today in the low to mid 30s.

500 mb shortwave trough will move out of the Great Lakes toward
00z and track west to east across the forecast area between
00-12z Wednesday. Southerly flow ahead of the shortwave will
spread warm frontal precipitation across the region beginning
after 18z in northern New York and into Vermont after about 22z, and
continue overnight into Wednesday. Diurnal cooling will be
offset by warm air advection tonight with a mix of precip types.
Western portion of New York zones the most susceptible to the
biggest mix, where warm air intruding up the St. Lawrence Valley
will allow for freezing rain to mix with sleet and snow. In
Vermont, below freezing temps through the low levels will keep
precip type more toward all snow although there will be a brief
period at the onset of the event with sleet mixed with the snow
for most all Vermont except the Northeast Kingdom.

With east to southeast flow below 850 mb expect to see greater
snowfall accumulations on the eastern slopes of the Green
Mountains and to a lesser extent on the northeast slopes of the
Adirondacks. Up to a half inch of precip forecast, equating to 3
to 6 inches of snow in east central Vermont and eastern Essex County
New York. Lesser snowfall amounts toward St. Lawrence Valley where
sleet/freezing rain mix lower snow ratios. Snow accumulations
out there to be generally 1-2 inches, with up to a tenth inch of
ice, mainly in southern St. Lawrence County. Southeast
downslope flow in the northern Champlain Valley, especially
northwest Vermont. This will keep northwest Vermont out of the advisory
with 2-4 inch snow totals.


Short term /Wednesday night through Thursday/...
as of 310 am EST Tuesday...combination of low pressure pulling
east off the New England coast and shortwave energy passing well
north of the area will keep some lingering moisture across the
north country for the short term period, with northwest flow
supporting higher chances for precipitation across the higher
elevations as compared to the valleys. Thermal profiles support
ptype mainly as snow through mid- morning Thursday but a warming
boundary layer will support a change to rain showers by
Thursday afternoon, though by then most of any precipitation
around should be waning as high pressure begins to build in from
the Ohio Valley. Lows Wednesday night remain very mild by mid-
January standards in the mid 20s to low 30s, and thursday's even
warmer pushing into the mid 30s to low 40s.


Long term /Thursday night through Monday/...
as of 310 am EST Tuesday...we've got a very quiet and very warm
period upcoming for the end of the week through the weekend as
surface high pressure settles over the region and strong ridging
develops aloft. Little to no precipitation is expected through
the period, with the big story being several days of abnormally
warm temperature with double digit daily departures from normal
likely. Mean 925-850mb temps hover right around 0c through the
period supporting highs in the mid/upper 30s to low/mid 40s each
day, and lows generally mid 20s to low 30s, a far cry from late
January standards of 20s for highs and single digits for lows.


Aviation /15z Tuesday through Saturday/...
through 06z Wednesday...VFR until 18z, then vis deteoriating to
IFR in -sn from west to east after 18z and ceilings lower to
MVFR as snow moves in with associated warm front. Winds will be
light and variable to start the period and then swing to the
south east around 10 knots for all stations except kmss which
will see northeasterly winds at 10 knots. Ceilings lower to LIFR
around 00-06z and remain for much of the night. Kslk/kmss sites
risk of freezing rain with up to an inch ice accumulation. Sleet
forecast kpbg/kbtv/krut/kmpv at onset of precipitation then
change to all snow aft 02z.

12z Wednesday - 00z Thursday...MVFR/IFR in periods of light
snow Champlain Valley eastward, mixed pcpn and/or light rain

00z Thursday through 00z Friday...VFR with brief MVFR/IFR
rain/snow showers.

00z Friday Onward...VFR.


Btv watches/warnings/advisories...
Vermont...Winter Weather Advisory from 4 PM this afternoon to 1 PM EST
Wednesday for vtz006>012-017>019.
New York...Winter Weather Advisory from 4 PM this afternoon to 7 am EST
Wednesday for nyz029-087.
Winter Weather Advisory from 4 PM this afternoon to 1 PM EST
Wednesday for nyz028-030-031-034-035.



National Weather Service Glossary of Abbreviations