Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Gray ME
950 PM EST Tuesday Dec 10 2013
low pressure will track to our south along a stalled frontal
boundary then exit into the Maritimes this evening. An Arctic
front will approach from the west drop south on Wednesday. A ridge
of high pressure will build in from the west Wednesday night and
Thursday. Another front will approach from the northwest Thursday
night and Friday. High pressure will build in from the north
Near term /until 6 am Wednesday morning/...
updated to include probability of precipitation a few more hours for lake effect moisture
/showers moving through New Hampshire and Maine and finally offshore. Very
narrow corridor of snow actually reaching the surface as boundary
layer dries out this evening. Amounts will be negligible. Dew
points...hourly temperatures...and sky cover were also matched to
Short term /6 am Wednesday morning through Wednesday night/...
on Wednesday...an Arctic cold front will drop into the region.
We'll see a few snow showers along with mountain snow squalls as
the front settles south across the area. The westerly trajectory
across the Great Lakes in advance of the front may enhance the
snow shower and squall activity across the Connecticut valley as
well as upslope sections of the White Mountains. Highs will reach
the 20s and lower 30s but it will feel a good 10 degrees colder
given the gusty westerly winds.
A few lingering snow showers Wednesday evening before the front
pushes offshore. Skies will gradually clear as a ridge of high
pressure builds eastward. Lows will range from near zero in the
mountains to about 10 above at the coast as the Arctic air deepens
across the forecast area. A west wind will make it feel even
colder with wind chills averaging 5 to 15 below zero.
Long term /Thursday through Tuesday/...
active weather conditions expected for the extended/long range
portion of the forecast. Some of the coldest air of the season
will be in place by Thursday morning. Readings in the north will
be below zero.
Scattered snow showers will break out ahead of the approaching...
secondary - and reinforcing Arctic front. Scattered snow squalls
will accompany this front as well...mainly across the high terrain
in the mountains. Upslope snowfall will occur with this
precipitation as well through Friday night over the northwest
facing terrain. 850 mb temperatures will be in the -24c to -26c
12z model suite continues to lock in on coastal storm for Saturday
night into Sunday. Each consecutive run appears to be colder and
colder...with Arctic air in place keeping the dry slot to our
south and just off the coast. This scenario would bump up our quantitative precipitation forecast
from earlier projections. Still very early in the game here...in
fact the Euro run keeps the heavy snow confined to southern and
central areas...with the north escaping the most precipitation as the
surface low moves northeast...then east...barely reaching
Model quantitative precipitation forecast is suggesting the potential for warning criteria
snowfall over southern and central Maine/New Hampshire. More
details to follow in tomorrow's discussions.
Aviation /03z Wednesday through Sunday/...
short term...brief MVFR through 22z vicinity of /kcon/ and /kpsm/
otherwise VFR expected. On Wednesday...scattered MVFR and brief local IFR
possible as an Arctic cold front brings scattered snow showers and
isolated snow squalls along with westerly wind gusts up to 25 knots.
Long term...VFR conditions expected Thursday. Areas of MVFR/IFR
ceilings/visibility in the mountains Thursday night and Friday. IFR/LIFR
ceiling/visibility developing Saturday night and Sunday.
short term...small craft advisories are likely on Friday. Gales
are expected Saturday night and Sunday.
Long term...i've reissued the Small Craft Advisory for all waters with the new
marine package this afternoon. Winds and seas should return to
small craft with wind gusts approaching gale outside the bays late
Wednesday as an Arctic cold front crosses the waters.
Marine...Small Craft Advisory until 6 PM EST Wednesday for anz150>154.