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nh discuss


Office: GYX

FXUS61 KGYX 211102
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
602 AM EST Wed Nov 21 2018

.SYNOPSIS...
An arctic cold front will drop south through the region later
today. The front will be accompanied by a few clouds along with
scattered snow showers and the chance for a brief snow squall.
A strong northwest flow follows the front tonight and Thursday
with record cold temperatures expected. High pressure will
build in from the west Thursday night then crest over the
region on Friday. The high will shift offshore Friday night and
will hold there through Saturday. A warm front will approach
from the south Saturday night and Sunday. Low pressure will
develop along the New England coastline early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

600 AM...Minor ESTF update to reflect the current mesonet in
near term grids.

Prev disc...
A quiet interlude at moment with some weak ridging between the
departing storm system over the maritimes and the 1008 millibar
low near Georgian Bay. GOES imagery showed scattered to broken
low cloud across the area with metars indicating some scattered
snow showers in upslope flow across the higher terrain. GOES
water vapor imagery showed a strong shortwave over the upper
Great Lakes. This feature will race east along with the
associated Georgian Bay surface low and drive an arctic cold
front across the forecast area late today. Ahead of this
boundary...clouds with a few sunny intervals outside the higher
terrain. Highs will range from the 20s across the mountains to
the lower and mid 30s elsewhere. Snow showers arrive by
afternoon with the frontal boundary with the highest pops found
across the higher terrain. There'll also be a few snow squalls
across the higher terrain with the frontal passage. A few of the
squalls may survive downwind of the mountains and produce some
brief travel headaches late today. Accumulations through evening
of an inch or two for the higher terrain and generally a dusting
elsewhere.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Behind the cold front...arctic air will spill into the area
tonight on a gusty northwest wind. There'll be some lingering
upslope clouds and snow showers tonight for the higher
terrain...otherwise expect clear skies in strong downslope
regime. On Thursday...Gusty Northwest winds of 15 to 25 mph will
produce wind chills more reminiscent of January or February
than November. Wind chill values of 5 below to 15 below for the
mountains...and 5 above to 5 below elsewhere. Actual air
temperatures will top out between 5 and 10 above zero in the
mountains with teens elsewhere. Those values will be about 25
degrees below average for the date.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A large Arctic high pressure system will crest over western
portions of the forecast area Thursday night after delivering
perhaps the coldest Thanksgiving on record to portions of
northern New England. A fresh snowpack along with light winds
and clear skies will allow for radiational cooling in some of
the sheltered valleys. Will hedge towards a colder solution than
most available guidance with lows forecast to be near or below
zero in northern areas by Friday morning and only single numbers
along much of the coast.

The high will allow for mainly dry conditions on Friday into
Saturday as it slowly heads to the east. However, by Saturday
night, moisture will begin to surge poleward around the
periphery of the circulation of the surface ridge. Below
freezing temperatures at the surface will combine with warm
temperatures aloft to product sleet and freezing rain across
much of the interior. Rain may be the dominating ptype right
along the immediate shoreline. This mixed precipitation will
change to rain over all but northern areas Sunday morning as
more warming gradually occurs.

Yet another coastal system will develop in our active pattern
early next week as suggested by some model consensus within the
00Z run. A strong upper level trough will cross over southern
New England, triggering cyclogenesis along the coastline on
Monday. The structure and evolution of this system has changed
somewhat from day to day and run to run. However, a slow moving
and strong and deepening area of low pressure had the potential
to bring significant precipitation to the region. Mixed
precipitation is likely once again, however this far out in time
will allow for changes in the potential details.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Short Term /through Thursday/...VFR. Sct MVFR in mtn shsn this
afternoon and evening with brief lcl IFR psb in snow squalls. NW
surface wind gusting to 30 kt tonight and Thursday.

Long Term...VFR Thursday through Saturday. IFR/LIFR ceilings developing
Saturday night...improving to VFR on Sunday. Ceilings and
visibilities decrease with a coastal low early next week.

&&

.MARINE...
Short Term /through Thursday/...Winds increase to strong gales behind
an arctic cold front late today...and may approach storm force
in gusts outside the bays by Thursday morning.

Long Term...Gale force winds expected Thursday into Thursday
night.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning from 2 PM this afternoon to 10 PM EST Thursday
     for ANZ150>154.

&&

$$

ES