Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 151540

Area Forecast Discussion
National Weather Service Gray ME
1040 AM EST Fri Dec 15 2017

High pressure shifts east today. Weak low pressure to our north
and south will provide clouds, and maybe a few snow showers or
flurries Friday night into early Saturday. High pressure builds
in on Sunday and starts a warming trend. Although slightly
warmer, several fast moving systems could provide some light
precipitation early to mid next week.


1030AM UPDATE...
Have updated the forecast to adjust for latest temperatures.
Have also tweaked PoPs a bit, introducing slight chance of snow
later this evening in southern New Hampshire as a shortwave
trough moves by to the south.

A very cold start to the day. Input latest obs data. No changes
needed to forecast at this time.

The long wave trof over the northeastern CONUS has two separate
approaching short waves that will be watched, one approaching
from the Great Lakes while the other races well out to sea from
off the mid Atlantic coast. In the meantime, high pressure
moves to the east later today. The day will start out sunny but
very cold. The afternoon will see increasing high clouds from
the southwest to northeast ahead of the approaching short wave
over the Great Lakes. Temps will start out very cold this
morning and will be slow to recover in the afternoon. Stayed
with a blend of guidance temps for highs.


An approaching short wave (clipper) from the Great Lakes will
spread clouds and scattered snow showers into the mountains
tonight into Saturday. Very limited moisture will be associated
with this system so little to no accumulations are expected.
Meanwhile the southern short wave that passes off the mid
Atlantic coast and then well out to sea may spread some ocean
clouds into some coastal areas for a time tonight but the
northern and western edge of the precipitation shield will stay
off the coast. Models in good agreement on this. Temps will be
not as cold tonight and Saturday and used a blend of guidance.


Northwesterly flow is established once Saturday`s system shifts
offshore. Throughout the end of the weekend and the beginning
of the work week the upper level flow will become southwesterly
with fast moving impulses moving through and bringing periods
of precipitation to northern New England.

At the surface high pressure builds in through the day Sunday.
A warm front lifts ENE into the region late Sunday into Monday.
This feature eventually shifts south but showers will be
possible across south NH and ME as it does so. A more
significant storm system drives a cold front through the region
Tuesday. The parent low will be located well to the north in
Canada...but widespread showers are expected through Tuesday
night. Upslope showers will be possible in the mountains through

High pressure noses in briefly Wednesday night into Thursday.
Another clipper moves just north of the region Friday into
Saturday. Warm advection showers are expected Friday as the warm
front lifts over the area...before a cold front sweeps through
late Friday.


Short Term...VFR expected with light winds. May see some light
snow arrive late tonight into tomorrow in the mountains as a
cold front moves in.

Long Term...MVFR conditions possible Monday and Tuesday in snow
showers. Otherwise VFR.


Short Term...Winds have diminished this morning and will become
light by this afternoon and evening. After the passage of the
clipper on Saturday the northwest winds will increase and become
gusty and may require a SCA over the outer waters.

Long Term...Next chance of SCA winds will occur Tuesday
afternoon and evening with gales possible on Wednesday/





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