Heavy Snow in Maine, December 11 to 12, 2016

Area Forecast Discussion
National Weather Service Gray ME
911 PM EST Sun Dec 11 2016

.SYNOPSIS...
Low pressure will approach from the west tonight and move through
New England on Monday...bringing plowable snows to the region.
The storm will move east into the maritimes Monday night. A series
of waves will bring successively colder and drier air from the
Arctic through the work week. A strong cold front will affect New
England for next weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
Update...
Have updated the grids to account for latest observation and
mesoscale models. Temperatures remain near afternoon highs over
southern areas while readings are falling over northern areas
and the Midcoast region of Maine where dew points remain in the
single numbers to around 10 degrees. Have adjusted first couple hours
of the temperature forecast, before non-diurnal temperatures occur
during the overnight hours.

Echoes continue to build over southern and central New Hampshire
as well as York County Maine late this evening. However, with
such a dry atmosphere in the lower portions of the atmosphere,
much of this is currently not hitting the ground. Expect virga to
continue until the 02Z-04Z period when snow begins to overspread
southern and western portions of the forecast area. This is
similar to the forecast philosophy using latest suite of mesoscale
models. Note that snow has begun on the summit of Mount
Washington.

Very little change to the forecast philosphy in our ongoing
forecast which sided with a cold solution to much of this evening.
Mainly snow for most areas, followed by a mix after the best
dynamics and vertical motions shift to our east. It is that point
that many southern areas and the coastline may shift to a period
of mix.

In any case, much of the precipitation will fall immediately
before and during the morning commute. This will make for very
trecherous and slow travel which has been highlighted in our
products and interviews with the media.

Prev Disc...
Clouds and precipitation from the developing low
pressure center is just starting to reach southern New England as
of 3pm. Clouds will rapidly spread northeastwards through the next
few hours. Temperatures across the region remain below freezing.
Surface air is still quite dry with a dew point depression of
around 10F so it will take a bit before the precipitation is able
to reach the ground. Steady precipitation will move in as snow
overnight and spread across the region by morning.

&&

.SHORT TERM /MONDAY NIGHT THROUGH 6 PM MONDAY/...
Heavy snow will be in place across the entire region by Monday
morning with poor driving conditions for morning commuters. As
discussed in prior update (see below) the vertical temperature
profile remains the biggest uncertainty. 12Z model guidance
continues to put a warm layer in through the coastline, which some
temperatures as high as 5C. At the surface however cold
temperatures continue to hold on with northwesterly flow
dominating. Additionally skies remain clear over CWA which will
allow for a strong surface inversion to set up across the eastern
portion of the CWA before the precipitation arrives. No major
changes in snow amounts or headlines from the 11am update.

11am update....
Have upgraded headlines from Winter Storm Watch to Winter Storm
warning and advisories. Timing and amount of QPF is on track and
have made little changes to that. All the uncertainty remaining in this system is in the
temperatures profile. Aloft consensus continues to be a bit
warmer, with above freezing air infiltrating through southern New
Hampshire before the precipitation can end.

Because of this have going with a slightly lower Snow Ratio as I
expect the snow to become more heavy and wet as the warm air
approaches. Along the coast a mix of sleet and rain will also
decrease totals. Because of this warm air intrusion have opted to
go with Winter Weather Advisories for most of New Hampshire. A few
of the higher elevations within Merrimack and Western Hillsborough
counties may see over 6" of snow but the lower elevations will see
mixing keeping the area wide average down slightly.

In Maine the main issue is the temperatures at the surface.
Morning lows were in the single digits all the way to the coast this
morning. 12Z KGYX sounding shows the depth of the surface based
inversion at around 600ft. Even as warm air tries to push in aloft
expect the surface temperatures to hold fast keeping a very tight
gradient in temperatures and snowfall amounts along the coastal
front. While the ocean temperatures remain in the upper 40s the
air temperatures at the coastal buoys remain near freezing
indicate the cold air dome is well established. Numerical guidance
continues to show the warm air pushing northwards at the surface
but have kept temperature increases lagging a bit compared to
guidance to allow the cold air to linger. The race between the
end of the precipitation and the warm air will be neck in neck
with temperatures not rising above freezing until the
precipitation comes to an end tomorrow afternoon.

Due to the lingering cold air and potential for the coastal front
to significantly enhance snowfall have upgraded to warnings for a
the foothills and interior of maine and Carroll county NH.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
A large pool of Arctic air will shift south from northern Canada and
descend towards the central CONUS, eventually reaching the
northern Great Lakes and points eastward during the mid week
period. This will be the coldest air in the entire northern
Hemisphere. In association with this modifying cold pool several
waves of frigid air will migrate south...especially affecting the
northeastern states Wednesday night onward. Timing of the various
waves or troughs will be about 24 hours apart or so...effectively
dropping the temperatures each day through at least Friday.

The NAEFS standardized temperature anomalies for this airmass
affecting the region the last half of the week are impressive.
The return interval for this type of cold in mid December is
completely outside of climatology. In addition the climatological
percentile (i.e. where would this forecast fall with respect to
climatology) is an all time minimum. In short while these
temperatures aren't that strange for late in the winter, it is a
bit early for this.

Getting into the dailies, wrap-around upslope snow showers will
linger for the higher terrain through early Tuesday morning. Weak
ridging builds in from the west during the day Tuesday. Clearing in
downslope areas will happen as early as Monday evening with sunny
skies for the first half of Tuesday for the coast and the
interior. The moisture/clouds never really diminish over the
mountains, and colder air will begin to dam along the mountains to
the north as the first cold wave approaches. Clouds will spread
south by Tuesday evening with scattered snow showers/squalls over
the mountains and foothills. For Tuesday and Wednesday
temperatures will range from the 20s north to 30s south. Coastal
locations will generally be a few degrees above freezing for
highs.

We will see a repeat of scattered showers and the upslope/downslope
pattern once again Wednesday and Thursday. By Thursday highs will be
in the +5-15 degrees F range across the north with lower to mid
20s south. The coldest night this week will be Thursday
night/Friday morning (with Friday night/Saturday morning a close
second). Lows dip to about 10 below north and near zero towards
the coast. With northwest winds gusting into the 20s all night,
expect to require a wind chill warning for Coos, Oxford, Franklin,
and central Somerset Counties and perhaps the notches of NH.

Much warmer air surges north for the weekend ahead of another
digging piece of the Polar vortex and deepening surface
cyclogenesis. This dynamic system will affect much of the central
and eastern CONUS with a strong cold front pushing through
northern New England over the weekend.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term...VFR conditions will rapidly deteriorate to IFR
tonight in snow. LIFR in +SN is possible in the early morning
hours. PSM PWM and RKD will see mixed precip develop mid morning
with IP and brief FZRA possible. Improvement is foreseen later
Monday afternoon.

Long Term...Upslope -SHSN may continue over HIE through Tuesday
morning. VFR conditions develop by Tuesday. Areas of MVFR
ceilings/vsby on Wednesday mainly for the higher terrain and
close to the coast as well on Thursday. VFR conditions Friday.
Gusty NW winds Thursday and especially Friday for all terminals.

&&

.MARINE...
Short Term... Winds will increase out of the southeast ahead of
the developing low moving through the Gulf of Maine tonight. Winds
will be highest over the eastern waters where the fetch is longest
and a Gale warning has been hoisted. The bays and remaining
Marine zone have a small craft advisory.

Long Term...SCA's may need to be extended through Tuesday for wave
heights and gusts to around 25 kts.

On Thursday gales may need to be hoisted for gusts.

&&

.TIDES/COASTAL FLOODING...
High astronomical tides on Monday combined with onshore flow will
bring water levels to near flood stage during the time of high
tide on Monday. At Portland the high tide is 11.3 feet at around 9
am Monday. Onshore flow will provide an additional 0.5-1 ft of
surge, bringing storm tides to around the 12 foot flood stage.
This may bring minor coastal flooding, mostly of the nuissance
kind, to portions of the coast, with minor splash-over possible
along the more vulnerable beaches. This advisory matches up well with
WFO CAR products for this event.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until 7 PM EST Monday for MEZ012>014-
     018>022.
     Winter Weather Advisory until 7 PM EST Monday for MEZ007>009-
     023>028.
     Coastal Flood Advisory from 8 AM to 10 AM EST Monday for
     MEZ023>028.
NH...Winter Storm Warning until 7 PM EST Monday for NHZ004-006.
     Winter Weather Advisory until 7 PM EST Monday for NHZ001>003-
     005-007>015.
     Coastal Flood Advisory from 8 AM to 10 AM EST Monday for
     NHZ014.
MARINE...Small Craft Advisory from 5 AM to 7 PM EST Monday for
     ANZ151>154.
     Gale Warning from 5 AM to 7 PM EST Monday for ANZ150.

&&

JC

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GRAY ME
256 PM EST SUN DEC 11 2016

MEZ023>028-122000-
COASTAL YORK-COASTAL CUMBERLAND-SAGADAHOC-LINCOLN-KNOX-COASTAL WALDO-
256 PM EST SUN DEC 11 2016

...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 7 PM
EST MONDAY...
...COASTAL FLOOD ADVISORY IN EFFECT FROM 9 AM TO NOON EST MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL MAINE AND
SOUTHWEST MAINE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.
   COASTAL FLOOD ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

NHZ001>003-005-007>013-015-122000-
NORTHERN COOS-SOUTHERN COOS-NORTHERN GRAFTON-SOUTHERN GRAFTON-
SULLIVAN-MERRIMACK-BELKNAP-STRAFFORD-CHESHIRE-EASTERN HILLSBOROUGH-
INTERIOR ROCKINGHAM-WESTERN AND CENTRAL HILLSBOROUGH-
256 PM EST SUN DEC 11 2016

...WINTER WEATHER ADVISORY IN EFFECT FROM 9 PM THIS EVENING TO 7 PM
EST MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NEW HAMPSHIRE...CENTRAL NEW
HAMPSHIRE...NORTHERN NEW HAMPSHIRE AND SOUTHERN NEW HAMPSHIRE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MEZ007>009-122000-
NORTHERN OXFORD-NORTHERN FRANKLIN-CENTRAL SOMERSET-
256 PM EST SUN DEC 11 2016

...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 7 PM
EST MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL MAINE AND
WESTERN MAINE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

NHZ014-122000-
COASTAL ROCKINGHAM-
256 PM EST SUN DEC 11 2016

...WINTER WEATHER ADVISORY IN EFFECT FROM 9 PM THIS EVENING TO 7 PM
EST MONDAY...
...COASTAL FLOOD ADVISORY IN EFFECT FROM 9 AM TO NOON EST MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN NEW HAMPSHIRE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.
   COASTAL FLOOD ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MEZ012>014-018>022-NHZ004-006-122000-
SOUTHERN OXFORD-SOUTHERN FRANKLIN-SOUTHERN SOMERSET-INTERIOR YORK-
INTERIOR CUMBERLAND-ANDROSCOGGIN-KENNEBEC-INTERIOR WALDO-
NORTHERN CARROLL-SOUTHERN CARROLL-
256 PM EST SUN DEC 11 2016

...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 7 PM EST
MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MAINE...SOUTH CENTRAL
MAINE...SOUTHWEST MAINE...WESTERN MAINE AND NORTHERN NEW HAMPSHIRE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER STORM WARNING.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER STORM WARNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

ANZ151>154-122000-
PENOBSCOT BAY-
COASTAL WATERS FROM PORT CLYDE, ME TO CAPE ELIZABETH, ME OUT 25 NM-
CASCO BAY-
COASTAL WATERS FROM CAPE ELIZABETH, ME TO MERRIMACK RIVER, MA OUT
25 NM-
256 PM EST SUN DEC 11 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

A GALE WATCH MAY BE NEEDED THURSDAY INTO FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

ANZ150-122000-
COASTAL WATERS FROM STONINGTON, ME TO PORT CLYDE, ME OUT 25 NM-
256 PM EST SUN DEC 11 2016

...GALE WARNING IN EFFECT FROM 5 AM TO 7 PM EST MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   GALE WARNING.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   GALE WARNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL OR RADIO IN SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.