Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
936 am EST Sat Dec 27 2014
a ridge of high pressure will keep the north country dry through
the daylight hours today, before moving offshore this evening,
allowing a cold front to bring rain and snow showers over the area
tonight. Drier and colder air will filter in behind the cold
front, starting a colder trend for the work week.
Near term /until 7 PM this evening/...
as of 935 am EST Saturday...updated forecast to reflect current
observations and satellite trends. No drastic changes as going
forecast is in good shape. Previous discussion follows.
Upper level ridge cresting over the region today, with inversion
keeping low level moisture over the area in the form of low level
clouds at least through this morning.
Enjoy the last full day of mild temperatures for awhile as
ridging at the surface and aloft dominate the weather across the
north country today. As surface high pressure to our south slides
eastward into the Atlantic today, the north country will be
influenced by south to southwest flow causing 850mb temperatures
to rise to 1c to 2c. With persistent low level clouds throughout
the day keeping temperatures from reach full warming potential,
expect surface temperatures to reach the m30s- m40s. Ridging will
also provide mainly dry weather today.
Short term /7 PM this evening through Monday/...
as of 345 am EST Saturday...surface gradient increases with
approaching cold front..along with a low level jet of 30-40kts at
925mb. Expect some gustier surface winds especially in the St Lawrence
Valley, of 15-30kts. This southwest low level jet will also cause
shadowing of precipitation fields in the Champlain Valley and portions of
the lower CT River Valley as precipitation associated with the
front spreads from northwest to southeast overnight tonight. Given the lack of
cold air at the surface and aloft...precipitation will mostly be rain with
snow possible at the summits for a brief period of time. So not
much accumulation expected.
Noticeably colder on Sunday through Monday as strong cold air
advection takes place behind the front. Temperatures will follow a non-
diurnal trend, cooling during the day Sunday and continuing to
fall Sunday night. So expected Sunday to start in the 30s to l40s
in the morning, but fall to the l20s-m30s Sunday afternoon. Cannot
rule out a flurry or light snow shower in the mountains...as low level
cold air advection helps squeeze out remaining moisture in westerly upslope flow.
Lows will range from the teens to M/u 20s on Sunday night.
Long term /Monday night through Friday/...
as of 316 am EST Saturday...west to northwest flow aloft is
expected to develop over the area in the Monday night through
Wednesday time period. This will allow for a large area of high
pressure to overspread much of the central and eastern United
States. Colder air will be associated with it...thus the trend
will be for colder temperatures to bring 2014 to a close. High
temperatures Tuesday and Wednesday will be in the middle teens to middle
20s despite sunshine and dry weather. This will be 10 to 15
degrees below normal. High temperatures will gradually return to
seasonal normals to start 2015...Thursday and Friday with some
snow showers possible as a weak upper level trough of low pressure
moves across eastern Canada and clips northern New England.
Aviation /15z Saturday through Wednesday/...
through 12z Sunday...VFR/MVFR ceilings will exist through 00z.
Eventually all areas will see MVFR ceilings after 00z and
continuing through the remainder of the period. There may be some
showers moving into northern New York after 02z and across Vermont
after 06z...but visibilities will remain in the VFR category
through the entire period. Winds will generally be 10 knots or
less through 00z...then increase from the south and southwest with
gusts in the 15 to 25 knot range.
Outlook 12z Sunday through Wednesday...
12z Sunday-00z Monday...scattered MVFR in rain showers along a
cold front. Rain showers mixing/changing to snow showers over
higher terrain late Sunday when colder air moves in.
00z Monday Onward...MVFR ceilings in northern New York with westerly flow
bringing lake effect clouds into the Adirondacks. VFR in Vermont.