Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 261052
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
652 AM EDT Wed Apr 26 2017

.SYNOPSIS...
Cloudy, cool, and wet conditions are expected today through
tonight as weakening low pressure along the mid atlantic coast
very slowly moves north to over Cape Cod Thursday and then into
the Gulf of Maine Thursday night. Expect an inch or two of rain
east of the mountains through tonight. By Thursday there will be
some improvement west of the mountains with warmer temperatures
arriving, while east of the mountains it will remain cloudy and
cool. Improving conditions and warmer temperatures across all
areas arrive for Friday. A cold front will pass through the
region Saturday with Canadian high pressure following for
Sunday. Another storm system looks to bring rain early next
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
645 am update: Rain across the area will continue. POPS look
good. Ingested latest obs data and only very minor tweaks to
temps since they have been fairly constant as well as uniform
due to the broad onshore flow.

Previous Discussion:
Low pres centered along the DELMARVA coast will very slowly
track northeast today. This will continue the bands of rain to
rotate north across the region combined with a raw onshore
flow. Temperatures will remain cool today considering water
temps still only in the lower to mid 40s and with onshore winds
can`t see temps moving much above 50 except over western areas
of NH. For practical purposes used blend of CONSALL with a
weight of the cooler NAMDNG for max temps today. This reflects a
cooler temp forecast today rather than straight guidance off of
the mav/met and some other models. POPS forecast and qpf
remains similar to prior forecast model runs. QPF still looks
heaviest toward coastal areas with much less in the mountains
and headwaters, generally around a half inch or so.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Tonight and Thursday the area of low pressure weakens as it
tracks northeast to over Cape Cod and then eventually into the
Gulf of Maine by late Thursday. A weak but continued onshore
flow will continue with the rain tonight becoming more scattered
by Thursday. Due to the low level air mass being at
supersaturation, areas of drizzle and fog over eastern and
coastal areas are expected into Thursday, this may continue
through the day especially along the coast. Guidance temps were
once again moderated for to the cooler side for highs on
Thursday with the NAMDNG guidance.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The long period period looks to feature a pretty progressive
pattern across the Northeastern states as weather systems move
through pretty quickly.

A warm frontal boundary looks to remain to our south Thursday
night. This will mean continued cool weather along with fog and
drizzle. The main question is how long does it take for the
murky low level airmass to be shunted out. Most guidance does so
pretty quickly on Friday while the latest ECMWF keeps it around.
This will have an impact on sensible weather such as
temperatures, clouds, and precip. For now took a blend of the
guidance while giving the ECMWF some credence. The best chance
of warming into the 70s will be across southern zones with
northern/eastern zones having the best probability of staying in
the low level soup for a good portion of the day. In addition,
much of the 00z model suite has a decent amount of elevated
instability Friday morning in advance of a short wave trough, so
cannot rule out thunder during this time as well.

Thereafter, a cold front will move across the region during the
day on Saturday. At this time PoPs look to be minimal at best as
this front will be moisture-starved. A cool, Canadian air mass
will be ushered in behind the front for Saturday night and
Sunday.

The early next week period looks to get unsettled once again as
another potent Plains system ejects out toward the Northeast.
This may mean more rain, fog, and drizzle for the area as
current model guidance generally agrees on onshore flow north of
a warm frontal boundary here which is pretty typical for spring.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Short Term...IFR/LIFR conditions in rain and areas of drizzle
and patchy fog today and tonight across most areas. LLWS
expected over eastern and southern areas this morning into the
afternoon due to the low level southeast flow aloft while
damming/nosing of high allowing light nne surface winds.
Conditions over western NH and northwest of the White Mountains
may remain MVFR. Low clouds and possible fog and drizzle will
keep conditions IFR through Thursday over eastern and southern
areas of ME while conditions over western NH and across the
mountains may be mainly MVFR Thursday.

Long Term...
IFR conditions are likely Thursday night in low clouds and fog.
Conditions will likely improve Friday, especially afternoon.
However, MVFR conditions are still likely along the coast as
well as northern and central zones. Still a chance IFR
conditions could hang on in those areas all day Friday into
Friday night as onshore flow continues. VFR conditions return
for Saturday and Sunday.

&&

.MARINE...
Short Term...The easterly flow shifts to southeast today as low
pressure approaches. Winds diminish below advisory levels but
wave heights will remain at or above 5 FT over the outer waters for
several days due to a continued onshore fetch. Inside the
protected bays, seas should subside to a 2-4 ft range so no
SCA`s will be needed.

Long Term...

Thurs night and Fri...Small Craft conditions remain likely
outside the bays, mainly for seas.

Sat and Sat night...Small Craft conditions once again possible
in association with cold frontal passage.VRB03

&&

.FIRE WEATHER...
Expect wet conditions area-wide today into tonight. Could see
somewhat warmer temperatures west of the mountains on Thursday
while it remains cloudy, cool, and damp east of the mountains
into Friday.

&&

.HYDROLOGY...
With continued snow melt river levels remain high. Add another
1 inch of rain on top of that and at least a few rivers could
rise close to flood stage. At this time no river is forecast to
reach flood stage, but it would not be out of the question for
some minor flooding to occur depending on how much rain falls in
key areas.

&&

.TIDES/COASTAL FLOODING...
High tide tonight is 11.5 FT. Although winds will become
more southeasterly at this point, there will likely be a
residual surge in the Gulf of Maine which could cause
another 0.5 to 1 FT surge leading to the potential for minor
coastal flooding and splash over.

The highest nighttime astronomical high tides are 11.7 FT after
midnight Friday and again Saturday mornings. With a prolonged
onshore fetch, albeit light, some minor problems are possible on
these tides as well.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT
     Thursday for MEZ023-024.
NH...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT
     Thursday for NHZ014.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150-
     152-154.
     Small Craft Advisory for hazardous seas from 8 PM this evening
     to 8 PM EDT Friday for ANZ150-152-154.

&&

$$
NEAR TERM...Marine
SHORT TERM...Marine
LONG TERM...Ekster



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