Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
1019 am EST Thursday Dec 12 2013
a weak ridge of high pressure will cross the region today quickly
followed by low pressure moving east through southern Canada. Low
pressure will pass by to the north overnight and a trailing cold
front will push south through the region on Friday. High pressure
will build in from the northwest Friday night and Saturday. Low
pressure over the Ohio Valley will redevelop off the middle Atlantic
coast Saturday night and will move northeast into the Maritimes on
Sunday. High pressure will build in from the west Sunday night
through Monday. High pressure will shift off to the east Monday
night as a warm front lifts into the area from the southwest. The
warm front will push east of the region on Tuesday followed by a
cold front. A secondary cold front will approach from the
northwest on Wednesday and will drop south through the region
Near term /through tonight/...
update...dropped Wind Chill Advisory as scheduled as temperatures
have bottomed out and will rise slightly today. Have also lowered
scas for the rest of this morning and afternoon.
Will be taking a good look at Arctic frontal passage late tonight and early
Friday. Expecting accumulating snow once again over the high terrain.
Previous disc...Arctic front currently push south of the forecast
area early this morning. Expect associated clouds and any
lingering flurries to clear out by daybreak. Expect the majority
of the day to be mostly sunny before clouds push into northern and
western zones late in the day. Brisk northwest winds this morning
will gradually subside this afternoon as a weak ridge crests over
the area. Despite the sun temperatures will show little change
from current readings and will average well below normal for the
day. Northern zones will only see highs from 5 to 15 degrees while
in the south temperatures will top out in the middle teens to lower 20s.
Short term /Friday through Friday night/...
weak low pressure crossing southern Quebec will bring thickening
clouds and a chance of snow showers overnight. Best chance for
snow showers will be in northern zones where and inch or two of
accumulation will be possible. Elsewhere amounts will generally be
a dusting to an inch. Clouds and increasing winds will help to
keep temperatures from falling too far but once again lows will be well
below normal. Lows will range through the single numbers in the north
and lower to middle teens in the south.
A trailing cold front will push south through the region Friday
morning. Cloudy skies and lingering snow showers will give way to
partly sunny skies in the afternoon. Strong northwest winds will
bring a re-enforcing shot of Arctic air into the region in the
afternoon. Expect highs ranging through the teens in the north
and lower to middle 20s in the south.
Long term /Saturday through Wednesday/...
high pressure noses in from the Great Lakes and southern Canada
Friday night and Saturday bringing fair skies but continuing the cold
weather...even as the core of the Arctic air mass stays just to our north.
Models show a short wave lifting NE along the East Coast Saturday night
and Sunday. The upper level feature is a positive tilted open wave that
moves quickly to the NE suggesting it will not provide a big snow
event though accumulating snow is certainly a possibility. The surface
low pressure tracks NE from the middle Atlantic coast...crossing the 40n
70w latitude/Lon benchmark for heavy snow event for our forecast area.
However...after it cross this benchmark it moves more to the east-northeast
rather than a preferred NE track for heavy snow. Surface low doesn't
deepen until after it has moved out of the Gulf of Maine and past
the Hague line due to the nature of the upper level support.
Some warm air tries to intrude into extreme southeast New Hampshire and the SW coast
of Maine where some mix is possible...but with high pressure locked in
to the north providing cold air funneling southward into the forecast area
on north NE surface winds expect that any mixed prcp would be sleet or maybe
some freezing rain...but not rain. Current trends suggest an
accumulating snow event is possible for the forecast area...developing
Saturday night then ending Sunday afternoon. Still plenty of time for
track, intensity and timing to change as models are known to do.
The low intensifies as it moves over the Maritimes with a strong northwest
flow ushering in very cold Canadian air for Sunday night and Monday.
High pressure builds in with very cold but dry weather on Monday. The high
and cold Arctic air mass exit to the east quickly Monday night as an upper
level trough and surface warm fnt move toward New England with southerly
flow bringing in warmer air along with some light snow Monday night and
continuing into Tuesday. A trailing cold fnt moves through late Tuesday
with mostly fair and seasonably cold weather to follow Tuesday night and
Used a blend of models and MOS guidance along with HPC quantitative precipitation forecast for
periods 4 and 5...then used a super blend of various models and MOS
guidance ... with bias corrected guidance and the previous
forecast for days 4 through 8.
Aviation /15z Thursday through Monday/...
short term...VFR today. Areas of MVFR/IFR ceilings and visibility
overnight and early Friday.
Long term /Friday night through Monday/...coastal low may produce
a snow event Saturday night and Sunday with IFR/LIFR conditions.
short term...scas will be lowered today.
Long term /Friday night through Monday/...conditions start out at
Small Craft Advisory levels Friday evening then drop below Small Craft Advisory levels as high pressure
builds back in later Friday night and Saturday. A coastal low may
bring strong gales late Saturday night and Sunday. Seas should build
significantly in response to the strengthening low pressure system per