Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 252256
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
656 PM EDT Tue Apr 25 2017

.SYNOPSIS...
Cloudy, cool, and wet conditions are expected through Wednesday
as low pressure slowly moves north along the coast. Expect an
inch or two of rain east of the mountains through Wednesday. By
Thursday there will be some improvement west of the mountains
with warmer temperatures arriving, while east of the mountains
it will stay cloudy and cool.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
655 PM...Updated forecast to adjust pops bit early this evening
/not raining yet in ern zones/, and to adjust temps somewhat
based on current obs, and tweak mins a bit, as it looks like
most places will bottom out in the 40-45 range, which mean in
places its already raining temps won`t change by more than a
couple degrees tonight. Otherwise rain and drizzle expected
through the night.


Previously...The next area of rain is on its way north into
southern New Hampshire and southern Maine this afternoon. This
round will be a bit heavier than the last. Expect more rain
arriving through the night as a slow moving cut off low tracks
north along the East Coast. Easterly flow to the north of the
low will transport cool, moist air in off the Gulf of Maine
while also promoting cold air damming. At the interface between
the damming and the onshore easterly flow a coastal front will
form and could enhance rainfall rates along the immediate
coastline.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Axis of heaviest rain shifts east along the coast during the day
on Wednesday. Continued damming will keep temperatures cool, but
increasing moisture from rain and moist advection off the
Atlantic will allow temperatures to warm into the low to mid
50s. Meanwhile to the west of the mountains downsloping
conditions will promote some clearing and warming during the
afternoon, with northern New Hampshire warming into the mid 60s.
While the synoptic scale forcing for rain moves east Wednesday
night, a lingering low level onshore flow will promote clouds,
fog, and drizzle through the night. With all the excess moisture
near ground level and at least some nocturnal cooling, there is
the possibility for dense fog to form.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
The models are in decent agreement on the longwave pattern
through early next week. We begin the period with a shortwave
impulse exiting into the maritimes. It`ll be followed by brief
ridging ahead of a broad deep upper trough over the western two-
thirds of the CONUS. A northern stream impulse crosses eastern
Canada and New England on Saturday with ridging to briefly follow
for Sunday. By Monday...a strong shortwave is lifting north into
the Great Lakes with associated surface system moving into the
Northeast CONUS for the start of the new work week. While the mean
jet position will limit cold air intrusion into the region...
we`ll still average near or only slightly above normal for the
period given the abundance of clouds and unsettled conditions.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Conditions will gradually become more permanently
IFR or worse this evening as steady rain moves in from south to
north. Conditions northwest of the White Mountains may remain
MVFR or even VFR depending on the intensity of the rain. Steady
rain moves east on Wednesday while low clouds and possible fog
and drizzle continue through Wednesday night.

Long Term...

Thu...Areas of MVFR with lcl IFR in -shra and fog.

Fri - Sat...Areas of MVFR in -shra.

&&

.MARINE...
Short Term...Easterly flow tonight shifts to southeast tomorrow
as low pressure approaches. Winds diminish below advisory levels
but wave heights will likely stay above 5 FT for several days.

Long Term...

Fri...Small Craft conditions are possible outside the bays.

Sat...Small Craft conditions are possible.

&&

.FIRE WEATHER...
Expect wet conditions areawide through Wednesday. Could see some
warming and drying west of the mountains on Thursday while it
remains cloudy, cool, and damp east of the mountains.

&&

.HYDROLOGY...
With continued snow melt river levels remain high. Add another 1
to 2 inches 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 at Portland is 11.0 FT. With a moderate
easterly flow over the waters expect a surge of 0.5 to 1 FT with
building wave heights. Have issued a Coastal Flood Advisory to
highlight the potential for splash over and beach erosion
tonight near the time of high tide south of Portland.

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

The next two nighttime tides are 11.7 FT but expect the surge to
be slowly draining by then and coastal flooding is not
anticipated.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT
     Wednesday for MEZ023-024.
NH...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT
     Wednesday for NHZ014.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ150>154.

&&

$$
SYNOPSIS...
NEAR TERM...Cempa/Kimble
SHORT TERM...Kimble
LONG TERM...Schwibs
AVIATION...
MARINE...
FIRE WEATHER...
HYDROLOGY...
TIDES/COASTAL FLOODING...


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