Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 171646
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1146 AM EST Sat Nov 17 2018

.SYNOPSIS...
A cold front over the Great Lakes will cross the area late
today accompanied by clouds and a few snow showers across the
higher terrain. Canadian high pressure builds into the region
Sunday before a fast moving area of low pressure develops over
the region Sunday night. An Arctic front will cross the region
late Monday, followed by high pressure building into the region
through midweek. A large storm may form along the southeastern
United States coastline late in the week and into next weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...
Have updated the forecast based on latest observations and
mesoscale models. Low clouds continue to gradually mix out snow
showers scattered across the higher terrain. Temperatures have
moderated with many areas already into the 40s over southern
areas, albeit low clouds and fresh snowpack will keep readings
in the 30s over northern areas.

Prev Disc...
600 AM...Minor ESTF update to reflect current satellite low
cloud trends and the latest mesonet in near term grids.


Prev Disc...
At 06z...a 1001 millibar low was along the Ontario-Quebec
border with a trailing cold front through the upper Great Lakes.
A 982 millibar low was near the eastern tip of Nova Scotia.
Clouds continue to wrap around the maritimes low into the region
on GOES infrared imagery...with some breaks in the cloud cover
noted downwind of the mountains. NWS Doppler Radar mosaic was
showing some light upslope snow shower activity across the
higher terrain. Little change for today with any sunshine
confined to the coastal plain in downslope flow. The cold front
and an associated impulse approach the area later today adding
to cloud cover and increasing pops for a time across the higher
terrain with its passage. Temperatures warm into the 30s across
the mountains with lower and mid 40s elsewhere...which is only a
few degrees below average for the date.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
The front sweeps offshore this evening with clearing in all but
mountain sections as upslope flow and a few snow showers linger
there. Lows will range from the teens to lower 20s. On
Sunday...we`ll be mostly sunny but colder than today as a ridge
of high pressure crosses the area. Highs will range from the 20s
across the mountains to the lower and mid 30s elsewhere.
sunshine will fade behind increasing clouds by afternoon across
southern New Hampshire into adjacent southwest Maine as a
frontal system over the mid Atlantic region begins to advance
northeastward into New England.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
This fall has been a typically frustrating forecast in a +ENSO
skewed neutral environment, which continues to show a +PNA trend
without quite locking in completely. There`s always some hope
for ridging in the ern CONUS, but we never quite get there.
Actually in the long range, downstream rex blocking over Europe
strengthens a bit which will help deepen the ern NOAM troughing
and build the Pacific ridge, so we will get into a fairly
amplified +PNA pattern. However, that building ridge pushing
poleward out of Scandinavia is forecast to break up the cold
air pool over the pole and Hudson Bay, which may just warm
things a little bit by next weekend. But it`ll remain below
normal through the holiday week.

A very weak 500 mb will approach from the SW Sunday night and
cross the region on Monday. FRom a dynamic standpoint it is far
from impressive, but it will ride along decent mid-level
baroclinic zone, so some thermal circulation will develop, and
will probably see a weak sfc low develop. Should be enough to
produce some light precip late Sunday into Mon morning, but
given dry air and the weak forcing, QPF is limited to around a
tenth of an inch, at most, for now. Still it will likely fall as
snow, and therefore some light accums will be possible. Lows
Sunday night will be in the evening, ranging from 15-20 in the
mtns to the mid to upper 30s on the coast and in srn NH. Highs
on Monday will generally be in the mid to upper 30s, but cooler
in the N.

%00 Mb trough axis doen`t move thru until Tue, and this will
pull some colder air down, and could sett of SHSN, with highs
Tues a few degrees cooler than Monday. The cold air will be
more noticeable Tue night when lows drop into the single digits
and teens.

A more impressive 500 mb trough, actually an extension of deep
upper lvl low over nrn Quebec, will dive into upstate NY Wed and
cross nrn New England Wed night. Best dynamics for this system
will stay N of the CWA, and will already have a cold and dry air
mass in place, but could see some SHSN or some squalls /mainly
in the N/ Wed afternoon and evening. Highs Wed will be 20-25 in
the N and in the upper 20s to low 30s in the S. The front will
cross the CWA late Wed evening, with NW flow picking up a bit,
so the cold air will fight with the downslope and prevent temps
from dropping off too much, buit it`ll still be cold with lows
Wed night into Thu morning generally ranging from around 10 in
the N to the upper teens in the south.

The cold air continue to spill in on Thu, but will be mainly
sunny. However, highs will range from 20-25 in the north to the
around 30 in the south, with a decent NW wind. NW flow will
persist into Thu night and sfc high finally builds in on Friday,
with highs in the mid 20s to mid 30.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Short Term /Through Sunday/...Sct MVFR in mtn clouds and
-shsn...otw VFR expected. Becoming VFR throughout aft 10z Sun.

Long Term...Could see a period of MVFR to IFR late Sunday night
into Monday morning, but otherwise VFR thru Wed.

&&

.MARINE...
Short Term /Through Sunday/...SCA`s likely continue outside the
bays into Sunday morning with marginal SCA`s for the bays
through this evening. We should drop below SCA`s on Sunday as a
ridge of high pressure traverses the waters.

Long Term...SCAs may be needed Tue night, but more likely Wed
night into Thu.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for
     ANZ150>154.

&&

$$
JC


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