Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 211220
Area Forecast Discussion
National Weather Service Gray ME
720 AM EST Tue Feb 21 2017
High pressure will crest over the region early today before
shifting offshore. A warm front will push east through the
region tonight. Low pressure moving east through southern Canada
will drive a cold front toward the region late Wednesday and
Wednesday night. The front will cross the region on Thursday
followed by high pressure Thursday night. A warm front will
approach from the southwest Friday and will lift north of the
area Friday night. A cold front will gradually push into the
region from the west on Saturday. Low pressure will form on the
front south of Long island and will move northeast through the
Gulf of Maine Saturday night.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Quick update to adjust temp/td/sky grids. High clouds will be on
the increase through early afternoon...mainly in western zones.
Sunshine will continue to fade behind high clouds across the
remainder of the forecast area during the afternoon. No other
changes planned attm.
High pressure will crest over the region early today and will
shift offshore this afternoon. After a mostly sunny morning high
clouds will filter in during the afternoon as a warm front
approaches from the west. Highs will range from the mid 30s to
lower 40s north and lower to mid 40s south.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Clouds will gradually lower and thicken tonight as the warm
front pushes in from the west. Very weak over-running with this
boundary will be diminishing as it moves into New England but
some light spotty freezing rain or sleet may hold together long
enough to make it into western zones after midnight. Models only
offering chance pops for the overnight hours so will not be going
with any headlines. Any areas of precip will likely be
highlighted with special weather statements toward the morning
commute on Wednesday. Lows overnight will generally range
through the 20s to near 30 degrees.
The front will wash out on Wednesday leaving the region in a
warm southwesterly flow. High temperatures will push well above
normal with most of the region topping out in the 40s to near
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Little change to the extended based on last couple of model
cycles. A fast moving Nrn stream s/wv trof is forecast to pass N
of the forecast area Thu. This will send a cold front towards
the forecast area...which should stall somewhere close by. NW
flow over the higher terrain will help generate some rain
showers...and snow at highest elevations...but little else S of
A more significant s/wv trof is forecast to lift thru the
Midwest...sending strengthening low pressure into Srn Canada.
Locally...the stalled front left behind from Thu will lift back
N as a warm front. This may be enough for a few light
showers...but widespread precip with this feature is unlikely.
It looks like there is growing consensus that we remain in the
warm sector...at least aloft...into early Sat. At that time both
21.00z GFS and ECMWF agree that the system will begin to
entrain moisture from a remnant cut off low off the Bahamas.
That will feed into a sharp cold front forecast to arrive across
the area Sat night. That will be our best bet at appreciable
rainfall. With high pressure sliding E into the Atlantic...temps
should be cool but remain above freezing. Cold front crosses the
area early Sun...with a follow up s/wv trof providing extended
chances for upslope showers into Mon.
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR today. Areas of MVFR ceilings developing
overnight. VFR on Wednesday.
Long Term...VFR prevails thru Thu at most terminals. Exception
will be HIE...where a passing cold front may bring SHRA late
Thu. MVFR conditions are possible there while upslope flow
continues into the overnight. More widespread MVFR or lower
conditions are possible Fri as a warm front lifts N thru the
area. Pockets of IFR or lower are possible in deep onshore flow.
This will continue into Sat...and then a strong cold front will
approach from the W towards evening. Steady precip will likely
only affect NH terminals prior to 00z Sun.
Short Term...Brief period of SCA`s may be needed for the outer
waters overnight but will let the day shift make the
decision on timing and extent.
Long Term...Winds and seas will generally remain below SCA
thresholds thru the end of the week. A sharp cold front will
cross the waters over the weekend...and bring an extended period
of SCA conditions to all waters.