Area Forecast Discussion
Issued by NWS Portland, ME

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089
FXUS61 KGYX 230801
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
401 AM EDT Thu Mar 23 2017

.SYNOPSIS...
Very cold air remains in place across the area today, though
winds will be a little lighter than they were yesterday. High
pressure will move across the area tonight with a warm front
crossing the area on Friday, bringing some light snow and rain.
Another cold front will drop south into the area Friday night
into Saturday, stalling south of New England. A wave of low
pressure will move along this front on Monday, spreading some
wintry precipitation into the region. A few more waves of low
pressure will move through the region Tuesday and Wednesday with
more chances of precipitation.

&&

.NEAR TERM /TODAY/...
Cold air is firmly in place across the area early this morning.
Early morning temperatures were generally in the teens to
single digits above zero. With the wind, there may be a few
places in the northern mountains that see wind chill values near
20 below, but this will not be widespread enough to warrant an
advisory. High pressure remains to our west, with the cold
northwest wind still blowing. This wind will not be quite as
strong today as it was yesterday, but it will still be
noticeably gusty. Temperatures today top out in the 20s to low
30s as some gradually warmer air begins moving in from above
today.

Temperatures at 850 MB are expected to warm about 8C from
yesterday`s 00Z sounding at Portland. Considering the
temperature at Portland at the time of last night`s sounding was
18 degrees F, this 8C increase would translate to about a 14F
increase in surface temperature assuming similar mixing (we will
not mix as high today as we did yesterday). Using this method,
we should expect a high temperature of 32F or less at Portland
today. This is significant because it would be the 11th day this
month that the temperature failed to rise above freezing, the
most such days ever recorded in March. We are currently tied
with several other years (most recently in 2014) at 10 days.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
High pressure crosses the area tonight allowing winds to go
calm. We should see at least a period of good radiational
cooling conditions in the evening before clouds increase from
west to east later in the night. By morning, warm/moist
advection aloft will be enough to begin spreading precipitation
into the area from west to east ahead of an approaching warm
front. Thermal profiles suggest that much of this precipitation
will fall as snow ahead of the warm front. There may be a
transition to rain as temperatures warm, but this will be near
the time that precipitation is coming to an end anyway. With low
level flow out of the south or southwest, this is not a flow
that would promote cold air damming so this should mostly be a
snow to rain event. It is possible that a few valley locations
in the north could hold on to some low level cold air and see a
brief period of ice. Overall snowfall amounts will be fairly
light, generally 1 to 2 inches, with warming temperatures likely
melting a good amount shortly after it falls. Precipitation
should come to an end outside the mountains by Friday evening.
Temperatures overnight Friday night will be fairly mild,
especially by recent standards, though a cold front dropping in
from the north will allow temperatures to fall back below
freezing again in the northern half of the area by morning.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Unsettled weather pattern with a series of systems with varying
precipitation types will continue to dominate the long term period.
Models are in better agreement in the near term for the weekend, but
continue to diverge more as time progresses. The biggest thing to
note is the continued chance of freezing rain from the system Sunday
night into Monday, which could affect the Monday morning commute.
Still a little out for the short term models to pick up on the
finer detail at this time.

After frontal passages on Friday...Saturday will be relatively mild
with near normal temperatures. A cold airmass will build in from
Canada and will cause below normal temperatures Saturday night and
Sunday.

The next frontal system will approach from the southwest and affect
the area late Sunday night through Monday. This is were the
uncertainty starts to be an issue due to the pockets of
freezing rain in Southwest NH and the coastal plain late Sunday
night into Monday morning. Overall the region will be dominated
by rain and snow from south to north.

On late Tuesday night through Wednesday, the next system will sweep
through the area from the west. This is the time frame with the
greatest model divergence giving the most uncertainty. Will not
rule out wintry mix in our region at this point.

Overall long term is based on the Super Blend guidance with
minor tweaks on Sunday night into Monday to put a chance of
freezing rain in the forecast.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Short Term...Expect VFR conditions today with northwest winds
not as gusty as they were yesterday, generally only gusting to
20KT. These winds will become calm tonight, with increasing
clouds from west to east by Friday morning. On Friday expect
lowering ceilings and a period of light snow possibly
transitioning to rain from west to east through the afternoon
and evening.

Long Term...Saturday will start out with limited MVFR in the region
and then have VFR conditions through late Sunday night. From
late Sunday night into next week will see areas of MVFR and IFR
due to ceilings, visibility and precipitation.

&&

.MARINE...
Short Term...Winds should fall below gale force across the
western Gulf of Maine by around 8AM, but freezing spray may
continue a few hours longer. Winds continue to diminish tonight
as high pressure moves across the waters.

Long Term...Small crafts should drop off by Saturday and return
again on Monday through Wednesday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until noon EDT today for ANZ153.
     Freezing Spray Advisory until 10 AM EDT this morning for
     ANZ150>154.
     Gale Warning until 8 AM EDT this morning for ANZ150>152-154.

&&

$$

LONG TERM...Becker



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