Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 252313
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
613 PM EST Sat Feb 25 2017

.SYNOPSIS...
Unseasonably warm temperatures will come to an end tonight as a
strong cold front will sweep across the region this evening
accompanied by showers and a few thunderstorms. A drier and
colder air mass follows this front for tomorrow into Monday. A
disturbance will approach from the west late Monday and Monday
night, followed by a larger system later in the week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
610 PM Update...Have issued a dense fog advisory for the coastal
plain as well as portions of central ME and the ME mountains.
Vsbys are rapidly crashing and should remain low until
prefrontal convective band moves in and passes through.
Otherwise, the line has weakened, but will still be watching for
some winds with it across western (especially southwestern) NH.
The ice jam flood potential remains.

405 PM Update...Have updated the forecast a little for a few
adjustments. Two concerns for this evening are river flooding
due to ice jams, and the other being the convective line
approaching from the west. Line of severe thunderstorms from
northeast PA extending northward to the ALB area continues to
move eastward. While the severity of the line is expected to
weaken considerably before reaching our CWA, it is not out of
the question that a few stronger cells may affect western NH. As
such have included gusty winds wording in the forecast along
with the thunder. Outside chance of one or two warnings near the
CT River in western NH around 00z this evening. Otherwise, we
are continuing to watch for hydro concerns, mainly in NH.

Previously...

Warm and moist airmass in place this afternoon with a robust
cold front approaching tonight. Expect conditions to remain
unstable enough now to mitigate most of the fog. Good dynamics
with the front should be strong enough to generate some isolated
thunderstorms and up to about a half inch to three quarters of
an inch of rain. Winds should come around to the north and west
quickly as fropa occurs during the overnight hours.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Cold air advection and tightly packed pressure gradient will
combine to produce gusty winds across the forecast area on
Sunday as temperatures begin to fall rapidly. Wind gusts are
expected to stay below advisory criteria. Colder temperatures
will also slow runoff and help to mitigate flooding
concerns...please see the Hydrology section for more
information. Wind begin to calm down Sunday night as pressure
gradient weakens and wind decouples under clearing skies.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
A weak cold front will drop south through the region on Monday.
The front will push into northern zones by early afternoon
producing a few snow showers. The front will continue south
through the afternoon producing little more than variable clouds.
Highs will range from the mid 30s to lower 40s north and mid 40s
to mid 50s south.

High pressure will build over the region Monday night. Expect
variable cloudiness overnight with lows generally ranging through
the 20s.

High pressure will gradually shift off to the east as a warm
front approaches from the south. Expect over-running ahead of
this boundary to lift northward into southern New England during
the afternoon. Will see an increasing chance of showers by late
in the day across southern New Hampshire and southwest Maine.

Warm front will continue to lift northward Tuesday night
producing showers in southern zones and a mix of rain and snow
in the mountains and foothills. Expect mixed precip to gradually
go over to rain toward Tuesday morning as warmer air continues
to lift north. Models showing little in the way of QPF overnight
with amounts of a tenth of an inch or less.

Warm front will continue to lift north Wednesday as low pressure
tracks northeast out of the southern Great Lakes. Looking for
occasional showers through the day with highs in the mid 40s to
lower 50s.

Should see a break in the rain Wednesday evening as over-running
shifts north of the area and low pressure shifts northeast into
the St Lawrence Valley. A trailing cold front will bring showers
back into the region Toward daybreak Thursday. Lows overnight
will range through the 40s.

Cold front will push east through the region on Thursday as low
pressure rapidly intensifies over the maritimes. Expect morning
showers to give way to partly sunny skies downwind of the
mountains. A strong northwest gradient will set up behind the
front Thursday afternoon and may touch wind advisory criteria by
late in the day. Upper trough swinging in from the west will
bring snow showers into the mountains late in the day. Expect
high temps to be reached in the morning before falling back in
the afternoon. Highs will range through the 40s north and lower
to mid 50s south.

Winds will continue Thursday night and into Friday as low
pressure slowly pulls away to the north. Lows Thursday night
will range through the teens north and upper teens to mid 20s
south.&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Short Term /through Sunday night/...Most locations are now VFR
with only a few IFR/LIFR locations remaining in fog. Those
remaining locations should improve over the next few hours.
Strong cold front will drag thunderstorms across the area this
evening and overnight, producing a period of MVFR/IFR
conditions. VFR conditions return for tomorrow, although gusty
northwest winds could produce some LLWS concerns.

Long Term...
VFR Monday with areas of MVFR ceilings in the mountains.
IFR/LIFR ceilings Tuesday and Wednesday. Becoming VFR Thursday
with areas of MVFR ceilings/vsby in the north.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
Short Term /through Sunday night/...Most locations are now VFR
with only a few IFR/LIFR locations remaining in fog. Those
remaining locations should improve over the next few hours.
Strong cold front will drag thunderstorms across the area this
evening and overnight, producing a period of MVFR/IFR
conditions. VFR conditions return for tomorrow, although gusty
northwest winds could produce some LLWS concerns.

Long Term...
VFR Monday with areas of MVFR ceilings in the mountains.
IFR/LIFR ceilings Tuesday and Wednesday. Becoming VFR Thursday
with areas of MVFR ceilings/vsby in the north.

&&

.MARINE...
Short Term /through Sunday night/...Southerly winds increasing
ahead of the approaching cold front will produce SCA criteria
across the waters. After the cold front passes, gusty northwest
winds are expected to produce Gale Force winds over the outer
waters tomorrow.

Long Term...Sca`s likely on Monday. Gales likely Thursday
afternoon into Friday.

&&

.HYDROLOGY...
The flood watch remains posted for interior portions of Maine
and new Hampshire through 00Z Monday. High temperatures in the
50s to 60s have resulted in a loss of 0.5-1 inch of snow water
equivalent in the past 24 hours. Additionally the cold front
moves through this evening with 0.50 to 0.75 inch of rain
possible. The snow melt and rain will bring area rivers to near
flood stage.

Additionally the warm temperatures have allowed for breakup ice
jam formation. Ice jam flooding occurred last night in
Bethlehem NH when the Ammonoosoc River jumped 5ft in under 15
minutes. River Gauge traces show ice movement on a number of
area rivers including the Sugar River, Pemi, in New Hampshire
and the Wild and Swift rivers in Maine. Ice jams both form and
dissolve rapidly and may form at any time.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch through Sunday evening for MEZ007>009-012>014-020-
     021.
     Dense Fog Advisory until 1 AM EST Sunday for MEZ008-009-
     012>014-018>028.
NH...Flood Watch through Sunday evening for NHZ001>009-011-012-015.
     Dense Fog Advisory until 1 AM EST Sunday for NHZ010-013-014.
MARINE...Small Craft Advisory until 7 PM EST Sunday for ANZ151-153.
     Gale Warning from 4 AM to 7 PM EST Sunday for ANZ150-152-154.

&&

$$

NEAR TERM...Ekster


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