Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 212157
Area Forecast Discussion
National Weather Service Gray ME
557 PM EDT Tue Mar 21 2017
An arctic front will push south through the region late tonight,
and produce a very cold and windy Wednesday. High pressure will
build in from the west Wednesday night through Thursday. High
pressure will shift east Thursday night. A warm front will
approach from the southwest Friday followed by a cold front
Friday night. High pressure will build south from Canada
Saturday through Sunday.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --6 PM Update...Have updated the forecast mainly in the PoP/Wx and
temperature departments. Loosely organized snow banding is
taking place across the western ME mountains, some of which is
heavy based on some web cams. The HRRR continues a pretty narrow
band of potentially mod-hvy snow through the evening,
particularly across higher elevations of Franklin County. Have
increased snow amounts to a few inches there. Otherwise, an
arctic front is expected to move through later tonight - perhaps
allowing for a band of snow squalls (mainly in the mountains).
Some mid lvl WAA associated with weak low pressure form ahead
of sfc cold front setting off a cluster of showers of rain and
snow moving across nrn zones at this times. This should shift E
in the next couple of hours, with a bit of a dry period. in the
hours around sunset. The sharp edge to the arctic air will move
through from late evening thru the pre-dawn. Scattered snow
showers are a good bet in the mountains, with some squalls
possible across the nrn zones. Models are stingy with bringing
much in the way of snow showers with the front into srn half of
NH or coastal plain of ME, but could see a few isolated SHSN
after midnight in these areas. Temps will drop slowly through
the evening, but once the cold front moves through the will
begin to fall off quickly late with lows 15-20 in the N and
around 30 in the south. Winds will also pick up fairly quickly
behind the front, but strongest winds will be during the day
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.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --Strong CAA and gusty NW winds behind the front will allow for
temps for temps drop through out the day, with highs early the
day. Winds will pick up during the morning probably to around 20
mph with gusts around 40 mph at times, especially in the
afternoon. Models keep gusts below wind adv criteria, but it
gets close, so will have to watch for potential advisory in some
Temps will fall thru the teens and 20s during the afternoon,
with wind chills in the single digits below zero in the
mountains, and in the single digits above zero in the south, so
it will be quite cold. The March sun will only go so far to
counteract the strong CAA. Upslope snow showers will continue
through the morning with some accums in the favored upslope
areas and on the higher terrain.
Winds will be slow diminish Wed evening and temps will continue
fall through the night, with wind chills dropping blow zero
everywhere and in the -10 to -20 range in the mountains. Lows
will bottom out from around zero in the north to around 10 above
on the coast and in srn NH.
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.LONG TERM /THURSDAY THROUGH TUESDAY/...
Broad upper ridge will gradually replace a departing trough Thursday.
Surface high pressure building in from the west will produce a
mostly sunny day...although temperatures will remain well below
normal. Highs will range through the 20s north and lower to mid 30s
High pressure will shift offshore Thursday night and return flow will
begin to bring warmer air back into the region. Expect high clouds to
spill over the ridge as a broad area of over-running set up to the
west. May see a few flurries or snow showers by daybreak but expect
any precip to be light and spotty generally falling off a mid
level deck. Lows will range from 5 to 15 north and will range
through the teens south.
Weak over-running precipitation will continue through the day Friday
ahead of a cold front approaching from the west. Will likely see
light snow mixing with or changing to rain in southern New Hampshire
and southwest Maine as boundary layer temps warm through early
afternoon. Models showing some differences in areal extent of
this warming with the ECMWF remaining significantly colder. In
any case QPF by the end of the day only amounts to a tenth of an
inch or less so any impacts will be minimal. Temperatures will
be fairly uniform across the region...ranging from the mid 30s
north to the mid 40s south.
Cold front will swing in from the west Friday night and will push
south of the area by Saturday morning. Looking for lingering rain
or snow showers to gradually end around midnight as the boundary
moves through. looking for partial clearing after midnight as high
pressure builds in from the north. Should see temperatures closer to
normal overnight with lows from the mid 20s north to the mid 30s
High pressure building south from Canada will produce a mostly skies
Saturday. Not a lot in the way of cold air behind the front as it
stalls just southwest of the area so highs top out above normal
ranging from the mid 30s to lower 40s north and mid 40s to near 50
Models diverge at this point with the ECMWF lifting the front
northward ahead of an approaching shortwave while the GFS parks it
to the southwest of the area. Have pretty much gone with SB numbers
for the remainder of the forecast and confidence quite low for days 6
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
Short Term...Could see some periods of MVFR overnight in SHSN at
KLEB, and especially KHIE, bit otherwise look for MVFR to
persist through Wed night. Strong NW wind gusts, to around 35kt
at times are expected on Wed, especially in the afternoon.
Long Term...VFR Thursday through Thursday night. MVFR/IFR
ceilings/vsby Friday and Friday night. VFR Saturday through
Short Term...Gales are now effect for all zones Wed into Wed
night, as strong NW flow moves in behind a cold front. With
very cold air spilling in, have issue fz spray adv for Wed
night. Wind should start to diminish a bit late Wed night.
Long Term...SCA`s likely Friday.
MARINE...Freezing Spray Advisory from 7 PM Wednesday to 10 AM EDT
Thursday for ANZ150>154.
Gale Warning from 8 AM Wednesday to midnight EDT Wednesday
night for ANZ153.
Gale Warning from 8 AM Wednesday to 8 AM EDT Thursday for