Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 240248
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
948 PM EST Wed Jan 23 2019

.SYNOPSIS...
The low will drag a trailing cold front across the area on
Thursday as it passes by to our north and west. Weak low
pressure will approach from the west Friday, before crossing the
region Friday night. A weak ridge of high pressure will pass
over the region Saturday. Low pressure will track through
southeastern Canada Sunday, before a cold front sweeps across
the region Monday. High pressure will follow on Tuesday. Yet
another area of low pressure will pass by to our north and west
Tuesday night into early Wednesday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
945 PM Update...Have extended a portion of the advisory in ME
until 3 am as low level cold air is going to tough to budge for
awhile. In addition, southwestern NH is beginning to warm up a
little more, so made the expiration a little sooner (3 am)
there. Otherwise, forecast largely unchanged.


515 PM Update...Have added portions of interior southern ME and
Belknap County NH to the winter weather advisory until
midnight. Temperatures on many mesonet stations still hovering a
couple degrees either side of 30 at this time with a
intermittent light rain beginning to fall. It should warm up
enough by midnight to mitigate the threat.

Previously...

A complex mixed precipitation event will impact the region
tonight into tomorrow.

Low pressure currently over Michigan will move northeastwards up the
St. Lawrence river valley. Ahead of the low pressure a warm front is
lifting through the region and warm air is already streaming in
aloft with higher elevation stations already well above freezing.
The southerly flow is also being reflected at the surface through
the coastal plain and foothills with a steady increase in both
temperatures and south winds. Some areas of the foothills remain
below freezing, as does the road surface temperatures and for this
reason have left light icing in the forecast through evening
and a winter weather advisory remains in place. Meanwhile north
of the notches the mountain valleys remain in an entirely
different regime. Berlin, Rangeley, and Jackman are barely
pushing 20F with the cold pool holding on tight. Have tried to
account for this temperature in the overnight trends with the
mountain valleys holding onto the cold air well into the morning
hours tomorrow. With this increased below freezing time comes
an increased risk for freezing rain and have extended the winter
weather advisory through mid morning to account for it. Further
south the foothills will likely rise a bit faster as they are
exposed tot he southerly flow and the advisory will end around
daybreak there.

Across the southern portion of the area the warm air moving over
the existing snowpack will lead to fog which may become dense.
Will need to monitor conditions for a potential dense fog
advisory overnight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Tomorrow expect the heavier precipitation to move into the
region as we remain in the warm sector of the cyclone. A very
impressive low level jet will move through midday ahead of a
cold front. While winds may exceed 65kts at just a few thousand
feet getting that wind to the surface may be difficult with the
surface based inversion expected to be in place. The most likely
location for stronger winds will be along the coast where the
temperatures are warmest and the southerly winds can accelerate
over the waters and thus a wind advisory has been issued for
this area. Additionally heavier precipitation along the front
may also help to mix down a few gusts to 40-45mph during the
middle of the day.

Temperatures will be much warmer than the past week but have
not been as bullish as some guidance would suggest. With the
south flow moving over 40 degree water have kept highs east of
Portland in the mid 40s with only southern New Hampshire
reaching 50F.

Additionally the warm temperatures over a cold snowpack will
lead to widespread fog and a dense fog advisory may be needed
for tomorrow evening. A cold front will sweep through the region
late tomorrow night changing precipitation back over to snow
before coming to and end.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Cyclonic flow aloft continues over the region on Friday with a
trough of low pressure approaching the region. This will allow
for mainly mountain snow showers over the region. As the
northwest flow increases with the passage of a secondary trough,
upslope snow showers will develop Friday night across the higher
terrain.

Cold, but mainly dry conditions will follow on Saturday.
Moisture will enter a weak ridge of high pressure, so clouds
will be over the region. Mainly cloud conditions will continue
Sunday as low pressure approaches from the west.

This area of low pressure will pass well north and west of the
region Sunday night, dragging an Arctic front across the region.
This will trigger more scattered snow showers, mainly in the
mountains. Cold conditions will return to the region Monday on
gusty westerly winds.

Yet another area of low pressure will approach from the west
Tuesday, before passing through Southeast Canada Tuesday night.
This system will bring another front to the region, this time
with more moisture than the preceding frontal passages. Any
snow will change to mixed precipitation from south to north late
Tuesday night and early Wednesday as 12Z model guidance
suggests warm air will move poleward during this period across
western Maine and New Hampshire. More Arctic air to follow on
Thursday.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term...Expect conditions to deteriorate to IFR overnight
tonight with FZRA moving in for the north and RA moving in from
the south. Winds will increase out of the south tomorrow with
gusty winds along the coast reaching 30kts. Aloft a very strong
LLJ will result in LLWS at all sites through the day on
Thursday.

Long Term...Scattered MVFR conditions in a few mountain snow
showers on Friday and again on Sunday. Areas of IFR conditions
developing Tuesday afternoon and continuing into early
Wednesday.

&&

.MARINE...
Short Term...Increasing southerly flow will reach storm force
on the eastern waters as a very strong low level jet moves
through the region. Have increased seas to 17-19ft along the
outermost waters. In the bays and further west have left gales
as the core of the jet will pass to the east however a few gusts
to storm force are possible.

Long Term...Gusty northwest winds and SCA conditions will be
possible Friday night and again on Monday. A strong southerly
gale may develop Tuesday night with gusty westerly winds to
follow on Wednesday.

&&

.HYDROLOGY...
With a storm total precipitation amount just over an inch across
southern New Hampshire do not expect any widespread flooding
concerns. A few rivers in this region may approach action stage.
Additionally urban nuisance flooding due to frozen and clogged
drains and culverts may also occur.

With the warmer temperatures and rainfall will have to keep a
close eye on the rivers for any potential ice jams. Due to the
significant snowpack expect most of the rainfall to be absorbed
and not runoff and this combined with the fairly brief period of
warmth should limit river rises and ice jam potential however
the more ice jam prone locations will need to be monitored.

&&

.TIDES/COASTAL FLOODING...
High astronomical tides will continue on Thursday. High water
levels will combine with building seas to possibly produce beach
erosion and splash-over near the time of the early afternoon
high tide. A coastal flood statement has been issued for early
Thursday afternoon.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 8 AM EST Thursday for MEZ012>014-
     020>022.
     Winter Weather Advisory until 3 AM EST Thursday for MEZ018-019.
     Wind Advisory from 8 AM to 9 PM EST Thursday for MEZ023>028.
     Winter Weather Advisory until noon EST Thursday for MEZ007>009.
NH...Winter Weather Advisory until 5 AM EST Thursday for NHZ001>006.
     Winter Weather Advisory until 3 AM EST Thursday for NHZ007-009-
     011.
     Wind Advisory from 8 AM to 9 PM EST Thursday for NHZ014.
MARINE...Gale Warning from 8 AM to 9 PM EST Thursday for ANZ151-153-154.
     Storm Warning from 8 AM to 9 PM EST Thursday for ANZ150-152.

&&

$$

NEAR TERM...Ekster
SHORT TERM...Curtis
LONG TERM...Cannon/Curtis
AVIATION...Cannon/Curtis
MARINE...Cannon/Curtis


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