Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 210103
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
803 PM EST Sun Jan 20 2019

.SYNOPSIS...Low pressure will move toward the maritimes
tonight. A strong northerly flow will persist over the region
tonight through monday night as high pressure builds in from
the west. High pressure will crest over the region by late in
the day Tuesday. High pressure will shift east Tuesday night.
Low pressure will slowly move out of the Great lakes and into
southwest Quebec on Wednesday. Low pressure will slowly move
east through southern Quebec Wednesday night and will drive a
trailing cold front through the region on Thursday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
8 PM Update...Have cancelled the rest of the winter storm
warnings as bulk of precipiation has quickly moved out. Cold
wind chill values will be the main story now through Monday.
Winds may gust up to 35 mph tonight through Monday.

655 PM Update...Have cancelled winter storm warnings across
portions of southern and central NH as precipitation for the
most part has ended. Further north, still getting reports of
freezing drizzle, sleet, and snow so will let those warnings
live on for a little longer. Otherwise, wind chill advisories up
where criteria is expected to be met which is -20F.

Previously...

It`s been quite a busy day across northern New England weather
wise. Low pressure is just now entering the Gulf of Maine and
current pressure falls show it moving northeast up the bay of
Fundy. The heaviest precipitation will come to an end from west
to east over the next several hours with scattered snow showers
lingering through evening. The warm air aloft that has resulted
in widespread sleet across the coastal plain will rapidly move
eastwards over the next few hours transitioning any remaining
precipitation back to snow. Have opted to leave the existing
winter storm warning in place with the expected snow showers as
well as patchy blowing snow.

The arctic air will filter into the region behind the departing low
with gusty north winds as the pressure gradient behind the existing
low remains overhead. Temperatures have been running colder than
most guidance all day and I don`t expect the trend to change much
overnight. Have dropped temps to slightly below the lowest guidance
for the evening. This will leave the mountains at around 10 to 15
below with below zero temperatures right down to the coast. Combined
with the brisk winds this will bring wind chills to below 20 below
across much of the area and a Wind Chill Advisory remains in place.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
Tomorrow the arctic chill continues with both cold temperatures
and northerly winds. the northern portion of the area will
likely see wind chills below 20 below all day and this may need
to be extended southwards into the foothills depending on the
overnight temperatures. Not much in the way of precipitation
although did hold onto just a slight chance of snow showers up
along the Canadian borer where even the driest of airmasses is
often able to eek out some snow. &&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
500 MB pattern now seems to shift to a lower wave number across
NOAM, with border troughs/ridges. Rex block setting up over the
atlantic with braid troughing across Canada and the central
CONUS. Looks like we will see smaller aves moving through this
larger scale trough, and the polar vortex does shift equatorward
toward James Bay during the period, so expect to the roller
coaster ride of temps, and systems every or 2 or 3 days. Earlier
model runs predictions of very cold outbreak not there any more
although we will see some periods of below, and abv normal
temps.

Monday night will be very cold, more so because of the wind
chill than the actual air temps as we hold onto gusty NW winds
thru most of the night as we get squeezed in the sfc gradient
between low slowly moving thru the maritimes, and approaching
high from the west. Air temps range from -10 to -15 in the N, to
around or just above zero in the south, but with the gusty
winds, wind chill range from -20 to -30 in the N to -10 to -20
in the south. Any evening snow showers in the mtns will wind
down after midnight.

Sfc high builds in Tue and Tue night, and will see warmer air
moving aloft, although diminishing winds on Tue may prevent a
well mixed day, should see highs in the mid teens to mid 20s
N-S and lots of sun. Tue night will start as a good rad cooling
night, but likely increasing SW flow and some cirrus moving
will keep temps from free falling. with low +5 to -5 in the N,
and 10-15 in the south.

The next chc of precip will be in the WEed-thu range, and looks
like low will develop over the GReat Lakes and cross across the
the CWA, rather than moving to our south. This will bring warmer
in ahead of it, and there p-type, especially in the south could
be mostly rain. I am not convinced of this yet, given the cold
snowpack on the ground, it should at least start as something
freezing or frozen, and may stay snow in the mtns. Still, will
take the wait and see approach here, and keep p-type uncertain
in the forecast for most of the area.

Should see some colder air move in for Friday into next weekend,
but it doesn`t look super cold, but probably a little below
normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
500 MB pattern now seems to shift to a lower wave number across
NOAM, with border troughs/ridges. Rex block setting up over the
atlantic with braid troughing across Canada and the central
CONUS. Looks like we will see smaller aves moving through this
larger scale trough, and the polar vortex does shift equatorward
toward James Bay during the period, so expect to the roller
coaster ride of temps, and systems every or 2 or 3 days. Earlier
model runs predictions of very cold outbreak not there any more
although we will see some periods of below, and abv normal
temps.

Monday night will be very cold, more so because of the wind
chill than the actual air temps as we hold onto gusty NW winds
thru most of the night as we get squeezed in the sfc gradient
between low slowly moving thru the maritimes, and approaching
high from the west. Air temps range from -10 to -15 in the N, to
around or just above zero in the south, but with the gusty
winds, wind chill range from -20 to -30 in the N to -10 to -20
in the south. Any evening snow showers in the mtns will wind
down after midnight.

Sfc high builds in Tue and Tue night, and will see warmer air
moving aloft, although diminishing winds on Tue may prevent a
well mixed day, should see highs in the mid teens to mid 20s
N-S and lots of sun. Tue night will start as a good rad cooling
night, but likely increasing SW flow and some cirrus moving
will keep temps from free falling. with low +5 to -5 in the N,
and 10-15 in the south.

The next chc of precip will be in the WEed-thu range, and looks
like low will develop over the GReat Lakes and cross across the
the CWA, rather than moving to our south. This will bring warmer
in ahead of it, and there p-type, especially in the south could
be mostly rain. I am not convinced of this yet, given the cold
snowpack on the ground, it should at least start as something
freezing or frozen, and may stay snow in the mtns. Still, will
take the wait and see approach here, and keep p-type uncertain
in the forecast for most of the area.

Should see some colder air move in for Friday into next weekend,
but it doesn`t look super cold, but probably a little below
normal.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Short Term...Conditions will improve from IFR to MVFR as the
snow moves off to the east this evening. Areas of blowing snow
will continue overnight under strong northerly winds. Ceiling
will gradually lift to VFR by tomorrow but the gusty north winds
will continue.

Long Term...Gusty NW winds persist at least into Mon evening,
with all terminal becoming VFR during the evening as well. VFR
will hold through Tue night, with possible flight restrictions
Wed aft into Thursday as next system arrive with possibly mixed
precipitation.

&&

.MARINE...
Short Term...Gusty northerly winds will continue overnight and
into tomorrow as arctic air filters into the region under a
strong pressure gradient. Have extended the Gale warning for the
bays another 6 hours as we are continuing to see some gusts to
near Gale force. On the outer waters expect Gale force to
continue through the day tomorrow. The combination of strong
winds and cold air and water temperatures will also result in
widespread moderate freezing spray and a Freezing Spray Advisory
remains in effect.


Long Term...Gales likely to persist thru Monday night, as will
moderate freezing spray. Both the wind and spray subside on Tue.
NExt chc for SCA will be late Wed into Wed night.

&&

.TIDES/COASTAL FLOODING...
Coastal flooding warning has been allowed to expire. Lower of
the tides tonight so not expecting any major issues. May need an
advisory for the high tide tomorrow which is 11.5 feet at
Portland.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Wind Chill Advisory from midnight tonight to 4 PM EST Monday
     for MEZ007>009-012>014.
NH...Wind Chill Advisory from midnight tonight to 4 PM EST Monday
     for NHZ001>009-011-015.
MARINE...Freezing Spray Advisory from 1 AM to 7 PM EST Monday for
     ANZ150>154.
     Gale Warning until 1 AM EST Monday for ANZ151-153.
     Gale Warning until 7 PM EST Monday for ANZ150-152-154.

&&

$$



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