Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 122102

Area Forecast Discussion
National Weather Service Caribou ME
402 PM EST Mon Nov 12 2018

High pressure crests over the region this evening and moves east
tonight. A developing Nor`easter will track across the Gulf of
Maine Tuesday and track in the Maritimes Tuesday night. The
coldest air of the season follows Wednesday and Thursday.

Clear skies will allow good radiational cooling initially this
evening and temperatures will drop to the teens north, but stay
in the upper 20s to lower 30s towards Bangor and the coast as
clouds increase. All areas should have recorded overnight lows
by around midnight and temperatures are expected to slowly trend
upward for the remainder of the night with the developing
southerly flow and warm advection. A fast-moving disturbance
moving in the southern stream bringing deep moisture from the
Gulf of Mexico will start to phase with with a vigorous northern
stream trough by late tonight and give rise to cyclogenesis off
the Mid-Atlantic coast. As this low is captured by the northern
stream trough, the low will rapidly deepen as it moves through
southern New England into the Gulf of Maine. In fact, the low
bombs some 35 to 40mb from Tuesday morning to later Tuesday
night. Broad isentropic lift will generate snow over northern
zones by daybreak through the morning. The rain-snow line will
start along a line from Bangor to Calais early in the morning,
but will push north towards by Greenville to Houlton line by
afternoon. Expected amounts fall well short of Winter Weather
Advisory criteria except possibly in southern Piscataquis County
where an advisory may be required...especially with snow
occurring during the morning commute. All of these southern
zones will be in the warm air when the heavier precip arrives in
the afternoon as the low reaches the Gulf of Maine with an
inverted trough extending northward. The exit region of a
powerful 200kt upper jet will cross the area simultaneously. The
low will likely close off at H925 and up to H850 as it tracks
towards Eastport in the afternoon. This is expected to cut off
the warm advection at the surface and aloft...allowing all snow
for a line running from north of the Moosehead Lake region
towards NE Aroostook. Banded snow will be possible in this
region during the afternoon as the low winds up with rates up to
an inch an hour. Kept snow ratios generally at 10 to one or
less. Omega in the DGZ isn`t too impressive...the DGZ is near
15K ft. The low will also be very progressive as it passes
through Maine...pushed by that 200kt jet. Overall snow amounts
in northern Aroostook are very close to warning criteria of 7
inches in 12 hours, but hold off on upgrading until 00Z guidance
can be reviewed.

Potential for a flash freeze Tuesday night as cold air quickly
rushes in behind the departing surface low. Any wet untreated
roads will quickly refreeze. Wind will also be increasing
through the night as the Canadian maritime surface low rapidly
deepens to the north. A wind advisory could be needed on
Wednesday due to this winds, but not looking like a significant
impact. The big story on Wednesday will be the record cold with
wind chill temperatures hanging around in the low single digits,
which is extremely cold for mid-November. Some record low high
temps are most likely to occur. Surface ridge moves over the
area on Thursday with some minor moderation in air temperatures
but it will still be near record low temperatures, the wind will
be light though. High clouds will be on the increase by late
afternoon as the next storm begins to approach from the south.

...Potential exists for the first widespread winter weather for
the Bangor and Downeast Region on Friday...

A developing coastal low is progged to move up the coast
Thursday night into Friday as the surface ridge quickly slides
off to the northeast. Forecast confidence is average for this
event with strong ensemble support in all model camps for this
system. There is still some spread with how far off the coast in
the Gulf of Maine the storm tracks. The GFS is the furthest east
solution with the CMC being the furtherest west. The ECMWF
camp trended a little further east over the last 24 hrs and the
GFS has trended slightly further west. The forecast track will
decide how much frozen precipitation coastal Maine gets. Still
too early to tell, but introduced a mix of sleet, snow and rain
on the coast for Friday with the forecast update as a mix is
possible with the current thermal profiles. Timing wise most
guidance has the storm out of the region by Friday night with
lingering snow showers across the higher terrain for the weekend
with another shot of cold air. Well below average temperatures
will summarize this whole period.

NEAR TERM: VFR conditions will remain in place until late
tonight. Late tonight, BGR and BHB will become MVFR due to cigs
and eventually IFR due to cigs and rain during Tuesday morning.
Further north of a line from GNR to MLT and HUL, snow will
reduce vis to LIFR...or VLIFR at times...towards daybreak and
continue all day. LLWS will be a threat towards BGR, BHB, and
coastal sites Tuesday afternoon.

SHORT TERM: Conditions will be improving Tuesday night across
northern TAF terminals as the snow begins to taper off. Winds
will be very gusty behind the departing area of low pressure
from the NW and this will last through the day on Wednesday. No
aviation impacts expected on Thursday, with the potential for
another storm on Friday.

NEAR TERM: Have converted the Gale Watch to a Gale Warning.
Looks like gale strength southeast winds will occur towards
late morning and then drop off for a few hours as low pressure
tracks across the waters. Gale strength northwest winds are
then renewed on the backside of the low by later in the
afternoon. Seas will reach up to 12 ft by later
Tuesday...possibly more.

SHORT TERM: Gale conditions will continue Tuesday night through
Wednesday with strong northwest offshore winds. Seas will remain
through the day on Wednesday. Conditions will improve by
Thursday as high pressure moves over the waters. Conditions will
trend down once again on Friday as another developing coastal
low is expected to impact the coastal waters Friday into
Saturday morning.

Record cold likely on Wednesday as a very anomalous airmass
moves over the region. Looking at the lowest high max temps at
Caribou and Bangor for Nov 14th, we have a very good chance of
breaking both these records, but not sure we will break any
record low temperatures based on the gradient winds keeping the
low levels mixed.

ME...Winter Weather Advisory from 4 AM Tuesday to 1 AM EST
     Wednesday for MEZ001-002-004>006-010.
     Winter Storm Warning from 4 AM Tuesday to 1 AM EST Wednesday
     for MEZ003.
MARINE...Gale Warning from 11 AM Tuesday to 1 AM EST Thursday for

Near Term...MCW
Short Term...Dumont
Long Term...Cornwell/Dumont
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