Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 220228
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1028 PM EDT Sun Oct 21 2018

.SYNOPSIS...
High pressure will build in from the west tonight and will
shift offshore on Monday as a weak warm front lifts into western
New England. Weak low pressure will slowly track southeast from
western Quebec Monday night and Tuesday, intensifying along the
Maine coast Tuesday night and then moving into the maritimes
Wednesday. This could bring a period of rain or snow Tuesday
into Tuesday night. High pressure will slowly build in from the
west late Wednesday through Friday.

&&

.NEAR TERM /OVERNIGHT/...
1030PM UPDATE...
Temperatures have fallen faster than expected in eastern areas
(Rockland and Waterville now below freezing) while clouds have
kept temperatures from falling as fast in northern areas
(Whitefield and Berlin have only dropped a degree or two in
several hours). Wind gusts have died down just about everywhere
now, so do expect cooling to speed up as the night goes on, but
clouds up north may linger into the night and keep temperatures
north of the mountains a bit warmer. Have made minor adjustments
to overnight temperatures based on these ideas. No other
significant changes are needed.

630PM UPDATE...
Winds are still a bit gusty out there, but they are on the way
down. Dewpoints have dropped into the low 20s and upper teens, a
sign of just how cold it could get tonight. It will take a
couple more hours before winds really die off and let
radiational cooling take hold, but by morning we should see a
few hours of good cooling especially in protected western
valleys. Temperatures this evening are already running a few
degrees below forecast, so dropped overnight lows a couple of
degrees as well, especially in favored cooling locations. Just
about everyone should drop into the 20s tonight, though some
upper teens are not out of the question if ideal cooling can set
up.

ORIGINAL DISCUSSION...
500 MB trough axis currently situated right over the CWA, with
some energy still trickling in from upstream making for good
stratocu production in the NW flow. Both loss of heating and the
fact that the trough shifts east should allow for clearing on
the coastal plain during the late afternoon and in the mountains
this evening as the flow weakens. Still decent flow overnight,
which will prevent radiational cooling, but will see cold
advection through a good chunk of the night, so lows will still
drop into the 20s in most spots.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
Monday will see lighter winds, and much more sun than Sunday as
surface high briefly builds in from the south. It probably
won`t be as cold aloft, but the lack of decent mixing will keep
temps mostly in the 40s, maybe reaching to around 50 in the
south.

Monday night will see clear skies in the evening with some
radiational cooling early but clouds will move in late and SW
flow on the boundary layer will increase from the SW, so temps
are likely to slow their fall or maybe even rise a bit after
midnight. A few SHRASN are possible in the mountains late, but
most of the precip from the next system will hold off until
Tuesday.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Trend of high amplitude upper ridge building along 110w still
indicating strong bundles of energy digging southeast thru the
data sparse areas of Saskatchewan and Manitoba and then into the
Great Lakes. US models finally coming more in line with EURO
solution. For this reason using superblend which incorporates
Euro but once again going with higher POPs than guidance and
lowering temps. Redevelopment of coastal and mid level low
expected somewhere along the southern Maine or NH coast area.
1.5-2.0 degs north of this center will be strong UVV and
enhanced QPF. Ptype will be an issue as model temps much too
warm due to seasonality and had to adjust them lower, also due
to drainage cross isallobaric winds and damming cold air. Nice
conveyer belt may also set up. The ole 72-96 hr rule of thumb
for the proportional upstream/downstream development looking to
work out nicely with models playing catchup. Confidence rather
high mountains may get a decent accumulation of snowfall Tuesday
night into Wednesday with a mix in some inland areas especially
higher terrain. Also considering amount of latent/sensible heat
due to the seasonably warmer ocean off the coast, expect this
extra amount of energy to help enhance the system even further.
Some heavy QPF may develop well inland north of the mid level
track into the mountains but will only hedge for now to avoid
flip flopping.

Wednesday the system continues to close off and deepen as it
moves into the maritimes bringing clearing in its wake over
downsloping areas as the northwest flow becomes strong and
gusty. In the mountains orographic snow showers will continue in
the cyclonic flow aloft combined with low level northwest
winds. Temps lowered from guidance on Wednesday once again.

Thursday/Friday the cold northwest flow will continue with some
gusty winds, some snow showers may linger in the mountains
Thursday.

The next system to watch will be late in the weekend as a
potential east coast storm develops first in the southeast and
then moves into the northeast. Astronomical high tides may come
into play with this system if it tracks as some models are
suggesting. Low confidence on track at this time though. For now
will keep an eye on continuity of models and that upstream
ridge at 110W.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Short Term...Mainly VFR through Monday night. The Gusty NW
winds will subside around sunset.

Long Term...MVFR/IFR stratiform mixed ptype overspreads the area
in the mtns Tue and in the form of rain elsewhere. Tue night
into Wed IFR conditions mostly snow in the mtns and rain or snow
in the foothills and other interior areas of higher terrain with
rain along the coast. Conditions improve Wed over developing
downsloping areas as winds back to the northwest and become
gusty. In the mtns and foothills MVFR/IFR conditions will
continue in snow showers. VFR conditions return Thu into Fri.

&&

.MARINE...
Short Term...SCA extended through tonight in the open wasters as
NW flow begins slacken after midnight. Winds/seas below SCA
Monday and Mon night.

Long Term...Timing and location of development of potential
coastal low in the Gulf of Maine late Tuesday into Wed will
determine strength and timing of backing northwest winds in its
wake. A lot of uncertainty remains for Tue night into Wed but
Gales may be needed Wed into Wed night.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 1 AM EDT Monday for ANZ151-153.
     Small Craft Advisory until 8 AM EDT Monday for ANZ150-152-154.

&&

$$

NEAR TERM UPDATE...Kimble
SHORT TERM...Cempa/Sinsabaugh
LONG TERM...Marine



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