Area Forecast Discussion
Issued by NWS Portland, ME

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
000
FXUS61 KGYX 201140
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
640 AM EST Fri Jan 20 2017

.SYNOPSIS...
Maine and New Hampshire will remain generally under the influence
of high pressure...with fair weather and warmer than normal
temperatures. A weak front will try and push into the area during
the weekend...but is unlikely to bring us much more than very
light rain or drizzle. On Sunday a cold front drops through the
area...bringing more cooler temperatures than precipitation. This
front will set up the battle ground between rain and mixed
precipitation or snow as the next weather maker moves up the coast
on Monday into Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
636 AM Update...
Have update the grids based on current conditions and latest set
of mesoscale models. Moisture remains trapped in the lower levels
of the atmosphere with cloud cover over New Hampshire and
communities just over the border in Maine. A second set of low
cover remains over eastern areas as well, with some sunshine
inbetween along portions of southwest Maine. Will increase cloud
cover forecast based on this trend.

Persistent low cloud cover, for at least a portion of this morning
will likely have an effect on the max temperature forecast. Have
nudged the forecast down a degree or two, but we will still be
above normal for this time of the year with most areas above
freezing and melting continuing.

Prev Disc...
Patchy morning fog will dissipate early this morning.
Thereafter, a northwest flow continues aloft while a surface area
of high pressure remains over the forecast area. However, some low
cloudiness will continue, especially over the favorable upslope
areas in the mountains as well as western portions of the forecast
area. This region will be in close proximity to a low level
boundary, allowing clouds to cross the region.

It will remain above normal with additional melting today.
Readings will be above freezing in all portions of the forecast
area with above normal readings.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
A weak upper level disturbance will bring more clouds to the
region tonight as it rotates and shears out into upper level
ridge. Weak dynamics and modest moisture supply aloft should
prevent precipitation during the overnight hours. However
increasing moisture in the lower levels could set the stage for
patchy drizzle/freezing drizzle or a few flurries. Confidence
level remains low in this low pop forecast.

On Saturday, spotty very light precipitation is expected despite
the weak dynamics involved with this system. There could be patchy
drizzle and a pocket or two of very light mixed precipitation as
well. The focus of any precip would mainly occur over New
Hampshire and the adjacent areas of western Maine.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
An exiting short wave in the maritimes allows a large surface
Canadian ridge of high pressure to build into northern New England
Sunday supplying a shot of cold air into the lower and mid levels.
In the mean time, the upper low tracking along the southern states
over the weekend gets ejected to the northeast and redevelops off
the mid Atlantic coast near DELMARVA and then tracks northeast
hugging the New England coast and moving along the Maine coast by
Tuesday. Strong UVV will accompany the upper system as it becomes
negatively tilted. Considering its source region in the deep
south, this system will have plenty of moisture that will
override the initial cold dome in place so the ptype will start as
snow across all areas. It gets complicated as to how much warm air
will work inland on the strong low level southeast jet.
Substantial snows could occur in the mountains and foothills
before any changeover while along the coast and adjacent inland
areas some light amounts of snow may occur before changing to a
mixed bag and then even some rain along the coast. qpf totals will
range from 1-2 inches over much of the area with highest amounts
along the coast. Snow accumulations ratios were based on
temperatures ranging from 8:1 along the coast to 13:1 in the
mountains.

The system exits into the maritimes by Wed with some clearing
although a dirty ridge will remain. A broad upper trof with an
associated cold front will bring a return to colder air and scattered
snow showers late in the week mainly to the mountains.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Short Term...MVFR conditions will continue over the western
portion of the forecast area with some low ceilings today. There
will also be patchy fog lowering visibilities through early this
morning. Otherwise generally VFR into tonight. A weak upper level
disturbance and low level boundary will remain over western areas
Saturday before shifting east. This will bring more MVFR
conditions with possible localized IFR conditions in patchy
drizzle and/or freezing drizzle.

Long Term...Conditions will lower to IFR/LIFR late Monday through
Tuesday in a mixed precipitation due to the coastal low affecting
the area late Monday into Tuesday. Conditions return to VFR by
Wednesday.

&&

.MARINE...
Short Term...Long period swells continue to reach the coast. The
SCAs for seas may need to be extended for a couple more hours this
morning. Will continue to monitor, however have raised the seas
forecast over guidance for this morning. More dramatic increase in
the seas will be noted for the extended portion of the forecast.

Long Term...A coastal low will develop off the mid Atlantic coast
late Sunday into Monday and then move north into the Gulf of Maine
with Gale force winds that may approach Storm force gusts for a
time Monday night into Tuesday. Seas will build to 15-20 feet over
the outer waters. The system exits northeast into the maritimes
Tuesday night and Wednesday with backing diminishing winds
allowing seas to be knocked down.

&&

.COASTAL SPLASH-OVER...
Despite being at the low part of our tide cycle, large building
waves may product some splash-over near the time of high tide
Monday night and Tuesday. Preliminary storm surge values appear to
be around 1.5-2.0 feet with a persistent easterly gale developing.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 9 AM EST this
     morning for ANZ150-152-154.

&&

$$
NEAR TERM...Cannon
SHORT TERM...Cannon
LONG TERM...Marine



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.