Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 131017
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
517 AM EST Wed Nov 13 2019

.SYNOPSIS...
Low pressure shifts northeast into the Canadian Maritimes
tonight. Gusty winds will allow very cold air to enter the
region tonight and Wednesday. High pressure will crest over New
England Wednesday night, with dry conditions and very cold air
over the region. Conditions remain dry until the end of the work
week as a frontal system crosses. While Friday looks warmer, it
is short-lived with an outbreak of Arctic-sourced air behind a
cold front late in the day. Below normal temperatures stick
around through the weekend with a warm trend and return of
active weather next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Arctic air will continue to pour into the region today on gusty
west to northwest winds as high pressure builds east from the
Great Lakes region. H8 temperatures in the -14C to -16C range
will be sufficient enough to prevent temperatures from rising to
above 32 degrees in most areas today. These would be mini-max
records for some areas.

Plenty of sunshine expected today due to downsloping in the west
to northwest flow. In the mountains, upslope clouds and
scattered snow showers or flurries possible this morning.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Record cold temperatures possible today and tonight.

The surface ridge crests over New England tonight. This will
allow for winds to go calm under clear skies. With a fresh snow
cover in some areas and low dew point values, temperatures will
plummet this evening. Temperature readings will quickly approach
record lows tonight. Have used a blend of guidance for
overnight lows which brings northern areas to below zero and
only single digits along much of the coastline.

Mid and high level clouds increase late tonight which should
prevent lows from falling even lower.

Scattered snow showers are possiblE on Thursday mainly in the
mountains as a broad upper level trough combines with low level
warm air advection. Southwesterly winds may bring some clouds
and perhaps a flurry or a shower to the Midcoast region of Maine
as limited moisture arrives off the Gulf of Maine.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The upper level pattern continues to be quite active during the
long term with the polar vortex wobbling over northern Canada
leading to an Arctic outbreak of cold this weekend. Meanwhile
weak mid- and low- level ridging dominates over the eastern
CONUS, which tends to keep the New England region dry. Next
week, long range models suggest the polar vortex retrogrades NW
closer to the North Pole which would allow for moderating
temperatures closer to average.

Thursday night, high pressure continues to erode and shift east
with southwesterly flow returning. Warm advection counters
diurnal cooling with near steady to warming temperatures
overnight, then leads to temperatures near normal Friday with
30s north, 40s to near 50 south. During the second half of
Friday, a shortwave and surface cold front crosses with strong
cold advection in its wake. While pre-frontal rain/snow/mixed
showers are possible over the Gulf of Maine and portions of the
Mid Coast early on Friday, the front itself appears by and large
moisture starved as crosses later in the day.

After frontal passage, though, strong northwest winds lead to
upslope snow showers and gusty winds as high pressure quickly
and robustly builds in at the surface. Strong flow and froude
exceeding 1 suggests snow showers and perhaps squalls spilling
from the upslopes into central/MidCoast Maine Friday night
before drying entirely by daybreak Saturday. So, have included
slight chance and generally boosted PoPs from the blend during
this period. Strong flow prevents radiational cooling, but
strong cold advection leads to single- digit lows across the
mountains and areas north with teens to near 20 south.

Big bubble no trouble/high pressure keeps the weekend quiet. A
cold start leads to temps struggling to the freezing mark at
best along the coast Saturday with areawide temperatures running
around 15 deg below normal. High pressure moves overhead
Saturday night with near 0F temps north and teens across the
coastal plain. Went on the low side of guidance during this
time. By the middle of the weekend, long range models agree on
a see-saw of troughing across the CONUS with a strong jet
descending across the front range of the Rockies driving a low
up the Atlantic coast by early next week.

The progressive nature of the western trough ought to keep the
coastal low beyond the benchmark, with any inland impacts
requiring an unlikely retrograding track to come to fruition.
Current model suite suggests the low passes to the SE Monday. One
impact of the coastal low is advecting warmer air aloft from
the south, allowing 850mb temps to come above freezing for the
first time in several days. Eventually the amplified western
trough tracks across the CONUS, returning active weather to New
England by the middle of next week.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
Short Term...VFR conditions with a few flurries this morning in
the mountains and localized MVFR conditions.

Long Term...VFR ceilings and visibility prevails through the
long term period, moderated by systems with brief restrictions
possible. Of note, a cold front crossing early Friday leads to a
wind shift with snow showers likely across the north. Cloud
cover may be dense enough at HIE to produce MVFR ceilings with
IFR visibility possible in heavier snow through Friday evening.
Onshore flow Sunday into Monday could lead to more widespread
low ceilings over the coastal plain.

&&

.MARINE...
Short Term...Gales remain in effect for the outer waters as
strong cold air advection continues over the relatively warm
waters in the Gulf of Maine this morning. SCAs continue for the
bays. Winds drop off rapidly tonight.

Long Term...SCAs at times through the long term period over the
waters. A system crossing Friday and Friday night brings
possible Gales under strong NW flow. Seas and winds ebb for the
most part this weekend under high pressure. An offshore low
builds waves and perhaps winds again early next week. Not a lot
of confidence in this system at this distance, but worth keeping
an eye on with the Gulf of Maine positioned between strong high
pressure to the north and strengthening low pressure to the
south.

&&

.CLIMATE...
Records for Portland
November 13, Coldest High (mini-max record): 33F set in 1990
November 14, Record Low: 12F set in 1986

Record for Concord
November 13, Coldest High (mini-max record): 33F set in 1962
November 14, Record Low: 7F set in 1986

Record for Augusta
November 13, Coldest High (mini-max record): 32F set in 1990
November 14, Record Low: 13F set in 1986


&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ151-
     153.
     Gale Warning until noon EST today for ANZ150-152-154.

&&

$$
NEAR/SHORT TERM...Cannon
LONG TERM...Casey


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