Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
245 PM EST Friday Nov 27 2015
cold front will cross our area late tonight and bring a few
showers along with it...especially across northern portions of
the forecast area. High pressure moves in behind the front for
tomorrow with cooler conditions expected. The next chance of
precipitation after tonight will come towards the middle of next
week with a potential storm system.
Near term /through tonight/...
even though the cold front will be coming through tonight the
temperatures will remain quite warm into the early morning hours
with cold air advection holding off until tomorrow. The cold
front will push into northern New Hampshire and Maine later this
evening and rain showers will likely develop across northernmost
zones by sunset. The rest of the area should remain dry until
early this morning. Forcing along the front looks to weaken as it
moves southward...so the best chance for precipitation we be in
the north this evening. Dry air moves in pretty quickly behind the
front...so thinking that any lingering showers will likely end
shortly after daybreak.
Short term /Saturday/...
high pressure will build in tomorrow behind the front and bring
cooler and drier conditions with it. There may be a brief period
of gusty winds in the morning with the frontal passage...but other
than that it is just looking like a cool day with decreasing
clouds as we head into the afternoon. Mostly clear skies with high
pressure overhead tomorrow night will send temperature
plummeting after sunset...but overall the lows will be close to
normal or slightly below normal for this time of year.
Long term /Saturday night through Friday/...
weather in the long term will be driven mainly by an ejecting
closed low currently over the 4 corners region. Gefs and ecens
were used heavily as operational models continue to have
differences in the long term.
Cold air advection will intensify Sunday as cold and dry air
spills from Canada into New England. Sunday night into Monday
surface high pressure shifts from west to east across the
forecast area. Winds become light and variable and then southerly
as high pressure centers itself over the Gulf of Maine. The
coldest air in the lower levels will be shunted off towards the
Saint Lawrence River valley and far northeast Maine. Still
Portland will be around -10c at 850mb with all areas above
freezing at 850mb by Tuesday.
On Tuesday the aforementioned closed low will reach the Great
Lakes region and a warm front will lift across New England. When
the front arrives in the early morning hours we will see mostly
snow showers across the north before areas mix with and change
over to rain. Late Tuesday night into early Wednesday morning we
will see snow mainly confined to the western Maine mountains.
Current thinking for midweek and beyond: upper level divergence
and 2-d pettersson frontogenesis increase Wednesday as the
surface cold front and upper level cold pocket approach. This will
allow cold air to once again dam along the higher terrain where
precipitation will change to snow. Confidence in this scenario is
low but growing. At this time it looks like measurable snowfall
may be in store for the mountains and perhaps foothills.
Aviation /19z Friday through Wednesday/...
short term...a cold front will pass the region late tonight and
MVFR conditions with some pockets of IFR will be possible into
tomorrow morning. VFR conditions are expected on Saturday as high
pressure builds back into the region.
Long term...VFR conditions Sunday with gusty winds likely. VFR
Tuesday with rain and snow beginning early Wednesday morning and
lasting throughout the day...bringing ceilings and visibilities
down at least to MVFR.
short term...southwest flow with moderate wind gusts of 25 to 30
knots will continue today out ahead of a cold front that arrives
later tonight. The winds will switch directions early tomorrow
morning to northerly after the cold front passes and winds will be
gusty for a period of time after frontal passage tomorrow morning.
Small Craft Advisory conditions should decrease by late tomorrow
Long term...there may be a gust or two near 25 kts Sunday night
as north winds push strong cold air advection across the Gulf of
Maine. Winds and seas approach small craft criteria Wednesday
night into Thursday behind a departing front.
Marine...Small Craft Advisory until noon EST Saturday for anz150>154.