Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 272316

Area Forecast Discussion
National Weather Service Gray ME
616 PM EST Mon Feb 27 2017

A weak cold front will drop southeast through the region this
evening and will be followed by a ridge of high pressure after
midnight. The front will lift north on Tuesday and Tuesday
night as low pressure moves northeast through the Great Lakes.
Low pressure will track northeast through the St Lawrence Valley
on Wednesday and will drive a trailing cold front through the
region Wednesday night. High pressure will gradually build in
from the west Thursday. Low pressure will move through southern
New England and out to sea on Friday. High pressure will build
in from the west Saturday.


615 PM Update...Have adjusted cloud cover a little bit over the
next few hours to make it a little cloudier in general away from
the immediate coast and southernmost NH. Otherwise, forecast is
on track with little in the way of change this evening.


Weak cold front will push southeast through the region this
evening...followed by high pressure. Looking for variable
cloudiness with this boundary this evening with clouds drying up
by midnight. Expect more clouds to push into southern New
Hampshire and southwest Maine toward daybreak Tuesday as weak
over-running shifts in from the southwest. Lows overnight will
range from the mid teens to lower 20s north and will range
through the 20s to near 30 south.


Clouds will be on the increase Tuesday as over-running
strengthens across New England. Will likely see some spotty
shower activity during the afternoon in southern and coastal
zones with spotty mixed precipitation in the north. Models have
been pretty consistent with QPF...only showing a few cents
worth....mainly in southern zones.

Over-running will continue Tuesday night as low pressure lifts
northeast out of the Great lakes. Once again QPF amounts will be
on the light side with one axis of heavier qpf remaining north
of the border in Canada and the rest offshore. Will likely see
some mixed precip in the north but with little or no impact.
Elsewhere expect occasional showers or drizzle. Lows will bottom
out in the lower to mid 30s north and mid 30s to mid 40s south.


Low pressure strengthens and moves up the Saint Lawrence River
Valley on Wednesday, March 1st. Best dynamics and overunning
will remain north and east of our area where highest rainfall
values expected. Less rain, around a half inch expected in our
forecast area Wednesday into Wednesday night. This precipitation
in itself is not expected to greatly effect the river. However,
temperatures as warm as +10C at H850 mb will be crossing New
England during the day. Plenty of low cloud cover expected,
however there may be breaks in the moisture with a southwesterly
flow through a deep layer. Very warm temperatures may aggravate
ice flows on the rivers. The record high of 58 degrees set back
in 1985 in Portland may be in jeopardy.

Light rain will continue Wednesday night along with mild
temperatures until strong cold air advection reenters the
forecast area late at night. A strong, gusty west to northwest
flow will result on Thursday. On Friday, the deepest of the cold
air will pass over our forecast area as arctic high pressure
settles to our south. H850 mb temperatures will bottom out at
-26C to -20C by late Friday night.

A large scale low pressure system will slowly exit out of the
Central Plain States over the weekend, with an intense area of
low pressure crossing the Great Lakes early next week.


Short Term...VFR tonight. Areas of MVFR/IFR ceilings developing
Tuesday afternoon and evening...mainly south. IFR/LIFR
ceilings/vsby Tuesday night and Wednesday.

Long Term...Mainly IFR or LIFR conditions Wednesday into
Wednesday night. High pressure builds in thereafter with
improving conditions.


Short Term...Continuing SCA`s through 700 pm.

Long Term...Gale force southwesterly winds are possible on
Wednesday, depending on the mixing values during the day. On
Thursday, brief gale force wind gusts are possible behind the
departing cold front.


River levels are continuing to drop as runoff has decreased.
Flows remain high across especially the southern portion of the
forecast area where greatest melting has occurred. The Ashuelot
in Cheshire county remains elevated but is expected to remain
below flood. In addition to the runoff, significant ice movement
on the rivers has occurred over the past few days. We are
monitoring several major ice jams currently in place.

The Pemigewassett at Plymouth NH has a 4 mile long ice
jam in place extending from approx 1 mile above the confluence
of the Baker River to below the town of Plymouth. Flows have
decreased to below flood stage however this jam is expected to
remain in place and may once again result in sudden increases in
river levels when flows increases.

The Carrabassett river has an ice jam in Embden. Flows have
decreased below flood but this jam remains in place with no
movement expected.

The Kennebec river at Augusta is ice affected however this ice
is not in as firm of a jam and may see some movement with
Tuesday night rainfall as well as tidal fluctuations.


MARINE...Small Craft Advisory until midnight EST tonight for ANZ150-152-



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