Area Forecast Discussion
Issued by NWS Portland, ME

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953
FXUS61 KGYX 131447
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
947 AM EST Tue Nov 13 2018

.SYNOPSIS...
Low pressure will track up the East Coast and bring snow and
rain to New Hampshire and Maine today. While many areas may
start as snow, expect much of the coastal plain and southern New
Hampshire to change to rain while more significant snow
accumulations are limited to northern areas. As the low moves
off to the northeast it will pull in some much colder air on a
strong northwesterly wind tonight and Wednesday. This cold air
will stick around through Thursday with the next Nor`easter
arriving on Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
940 am Update: WAA aloft continues to push the rain/snow line
north. Radar showing the area of nice bright banding (corr
coef) continueing a northward advance into the mountains.
Current fcst has this changeover handled rather well with only
some minor tweaks as sfc temps still trending a few degs colder
than fcst. Rain and QPF fcst for central and southern areas
looks good for the rest of this event today.  No sig changes
needed at this time.

700 AM Update... Rain/snow line continues to make slow
northward progress early this morning...currently pushing into
the foothills of Maine and New Hampshire. To the north...heavy
wet snow continues to fall with most areas reporting 1 to 2
inches.

Expect low level cold air to gradually be scoured out through
the morning in the foothills with snow going over to sleet and
gradually mixing with rain by early afternoon. Have adjusted
pops/wx temp/td grids based on latest radar trends and surface
obs but no major changes planned to current forecast.

Prev disc...
Low pressure moving up the mid Atlantic coast has spread a
variety of precipitation across most of the forecast area early
this morning. After a brief mix...precipitation has gone over to
rain across southern New Hampshire and coastal and southern
interior Maine where around an inch of QPF is expected through
late afternoon.

Farther north a mix of sleet and snow showing up
in surface obs in the foothills of New Hampshire and western
Maine where winter weather advisories are in effect. Expect this
precipitation to mix with rain or go over to all rain later this
morning into this afternoon.

In the mountains... light snow is falling and expect this
activity to pick up later this morning as better dynamics push
northward. Still looking for 6 inches or more...especially over
the higher terrain. Snow may mix with sleet or rain later this
afternoon in the northern Connecticut Valley but the remainder
of our northern zones should remain in the form of snow. Looking
for steady or slowly rising temperatures today with highs
topping out in the mid to upper 30s north and lower to mid 40s
south.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Precipitation will quickly wind down by late this afternoon or
early evening but may persist in far northern zones into the
evening as upslope flow kicks in behind departing low pressure.
Northwest winds will increase across the region later tonight as
low pressure continues to intensify as it pulls away to the
northeast. Looking for clearing skies overnight downwind of the
mountains. Lows by Wednesday morning will range from the mid
teens to lower 20s north and will range through the 20s south.

Wednesday will be very cold and blustery with northwest winds
gusting to 40 to 45 mph. Will be holding off on wind advisories
for now but will likely be needed throughout the forecast area.
Despite partly to mostly sunny skies in southern zones highs
will barely get above freezing. Even colder readings will be
found in the north with highs only in the mid teens to mid
20s...very close to overnight lows.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Very cold night expected Wednesday into Thursday morning with
high pressure shifting over the region, continued CAA on gusty
NW winds and a fresh snow pack all support extremely chilly
overnight lows on the order of single digits north to teens
south. However, haven`t gone as low as theoretically possible as
winds still in the 5-10 mph range due to the high being
displaced slightly to the northwest and some lingering clouds
across the mountains. Winds will be coming down, so despite the
cold a wind advisory will not be needed. Thursday temperatures
rebound some into the 20s and 30s.

High pressure shifts offshore Thursday night a southern stream
short wave moving through the southeastern states allows a
cyclone to deepen near the Delmarva Peninsula. This system will
eject towards the Gulf of Maine, staying inside the 40N/70W
benchmark. Models are in better agreement as to the track of
this system with the latest runs, which keep it south of Nova
Scotia as it shifts east Friday night.

Precipitation should start late Thursday night and spread
across the entire region by daybreak Friday. The low will be
well enough offshore so that p-type will be mainly snow
everywhere, with perhaps some rain along the coast later in the
day as the low makes its closest approach. This is likely the
first multi-inch snow event for many areas with amounts in the
advisory range possible across much of the area.

The system quickly exits northeast into the maritimes by later
Friday night with clearing in its wake with weak high pressure
moving in for Sat. What snow falls will melt for much of the
area Saturday as temperatures rise into the mid 30s north to
lower/ mid 40s south. Some lingering snow showers expected in
the mountains during this time.

A weak system will send another cold front into the area early
in the weekend, primarily creating more nuisance snowfall for
the mountains. Yet another reinforcing weak cold front arrives
for Monday into Tuesday bringing some light showers. High
pressure builds in thereafter. Sunday through Tuesday
temperatures will moderate some during the daytime with highs in
the mid 20s to mid 30s.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
Short Term...MVFR/IFR ceilings and vsby today....improving to
VFR late. VFR tonight with areas of MVFR ceilings and vsby in
mountains snow showers. VFR Wednesday.

Long Term...Strong gusty NW winds to 40+ kts possible through
Wednesday night with winds subsiding late. VFR conditions
Wednesday through Thursday. Conditions lower to IFR/LIFR late
Thursday night over southern areas and all areas by Friday.
Conditions slowly improve to VFR later Friday night. Lingering
MVFR conditions expected in the mountains into Saturday.

&&

.MARINE...
Short Term...
Continuing gales for the outer waters today and all waters after
midnight.

Long Term...Strong Gale force winds continue late Wednesday
night but will begin to diminish from west to east by Thursday.
A SCA will be needed for the outer waters and perhaps Penobscot
Bay ending by the afternoon as winds finally drop below 25 kts.
The next coastal low is expected to track near Cape Cod on
Friday into Friday night with stronger winds possible ahead of
and behind this storm as the center tracks across the coastal
waters of the Gulf of Maine.

&&

.HYDROLOGY...
Rainfall amounts today are not expected to cause any river
flooding at this time. The closest point to flood will be North
Chichester on the Sun Cook River which is forecast to stay just
below flood stage. However, ponding of water on roads and other
low lying areas is expected.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until 7 PM EST this evening for
     MEZ007>009.
     Winter Weather Advisory until 7 PM EST this evening for
     MEZ012>014.
NH...Winter Storm Warning until 7 PM EST this evening for NHZ001.
     Winter Weather Advisory until 7 PM EST this evening for
     NHZ002>004.
MARINE...Gale Warning from midnight tonight to midnight EST Wednesday
     night for ANZ151-153.
     Gale Warning until midnight EST Wednesday night for ANZ150-152-
     154.

&&

$$
NEAR TERM...Marine



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