Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 211144

Area Forecast Discussion
National Weather Service Gray ME
644 AM EST Sat Jan 21 2017

Expect warm temperatures today as an upper level ridge crosses
the region. A cold front will drop south out of Canada Saturday
night into Sunday morning, bringing cooler weather again. A storm
system tracking up the coast will bring wintry precipitation to
the area late Monday and Tuesday. A cold upper trough will remain
over the area through the latter part of the week with a return
to colder temperatures. Scattered snow showers in the mountains
and foothills can be expected through the latter part of the week.


Have updated the forecast based on current trends and latest set
of mesoscale models. Very mild conditions persist for this time of
the year and this time in the early morning hours. Have adjusted
temperatures upwards based on latest trends.

Plenty of low cloud cover will remain in place in the forecast
area with patchy fog dissipating over the next hour or two. Models
continue to bring a slight chance for mixed precip over far
northern areas today. This is a low confidence forecast for any
measureable precip.

Prev Disc...
High pressure will remain over the forecast area today. However,
low clouds will continue to dominate the region. A weak impulse
shearing into the upper level ridge may bring some very light
precipitation to northern New Hampshire today as well as areas in
adjacent northern Oxford County.

Most areas will start the day warm and climb through the 40s
during the afternoon. However, it will be cool enough at the onset
early today to allow for a least the chance for light icing in the
far north. This is a low confidence, low probability event and
will need to be monitored over the next several hours.


There is still a chance of a light mix across the far north
tonight in close proximity to the weak shearing short wave. This
is also the area where cold air advection will begin during the
late night hours.

Cold air advection will continue on Sunday as a backdoor front
sweeps towards southern New England. Canadian high pressure will
begin to nose southwards into the region. The best chance for
precipitation, albiet low, will be over western New Hampshire
where there could be a period of light rain or light rain and
snow. This sets the stage for the extended forecast and
cyclogenesis along the Mid Atlantic coastline.


A slow moving upper low currently tracking along the southern
gulf states will be kicked northeast toward the mid atlantic coast
Monday and reaching the Gulf of Maine by Monday night. The system
will come from a source region with plenty of moisture so total qpf
amounts from the system look to be in a range from a half inch in
the mountains to over 2 inches over southern coastal areas.
PTYPE will become a major issue with this system. Initially hgih
pressure stacked to the north allows a dome of cold air to be in
place allowing the precipitation to start as snow but with the
strong low/mid level southeast jet in advance of the negatively
tilted trof approaching, temps aloft and in the low levels will
quickly warm allowing the snow to change to rain along the coast
and a mixed bag inland. Models indicate depth of cold air will be
enough well inland to allow moderate of amounts of snow before the
changeover. Problems with this forecast will also be the boundary
layer temps well inland after the warm air works inland aloft
allowing for some pockets of freezing rain or sleet to develop.
Along the coast some gusty winds are possible Mon night.

Models generally agree the bulk of the precipitation will be over
by Tue morning but still some scattered snow showers to continue
in the mountains and foothills.

Mid to late week generally a broad cyclonic flow develops over the
northeast allowing snow showers in the mountains and foothills
with a return to a colder air mass for the rest of the week.


Short Term...Mainly MVFR conditions in low clouds. Any patchy fog
will dissipate quickly this morning.

Long Term...IFR to LIFR conditions expected with mixed
precipitation to develop Mon afternoon and continue Mon night
into Tue. Conditions improve to VFR over southern areas by late
Tue while in the mountains MVFR conditions will continue Tue night
into Wed with scattered snow showers.


Short Term...Mainly quite conditions ahead of the next storm.
Winds and seas will remain below Small Craft Advisory thresholds.

Long Term...A strong east flow will develop ahead
of an approaching coastal low. High confidence of Storm force
winds developing over the outer waters Mon afternoon through Mon
night. In the bays gale force winds are likely. Seas will likely
build to 15-20 over the outer waters. Winds diminish Tue as the
surface low moves overhead and then into the Canadian maritimes by
Tue night. High pressure and a light westerly flow will move
across the waters Wed.


Despite being at the low part of our tide cycle...large building
waves may product some erosion and splash-over near the times of
high tide Monday night and Tuesday. Preliminary storm surge values
appear to be around 1.5 to 2 feet with a persistent...strong
easterly wind developing.


MARINE...Gale Watch from Monday afternoon through late Monday night for
     Storm Watch from Monday afternoon through late Monday night
     for ANZ150-152-154.


NEAR TERM...Cannon
LONG TERM...Marine is the U.S. government's official web portal to all federal, state and local government web resources and services.