Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 241631
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1231 PM EDT Sat Jun 24 2017

.SYNOPSIS...
Tropical moisture from the remnants of Tropical Storm Cindy and
a passing frontal system will bring scattered showers and
thunderstorms this morning. A series of surface troughs and weak
cold fronts will cross the area this weekend into early next
week bringing us the chance of showers from time to time...
especially in central and northern areas.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...
Radar continues to show a line of showers exiting out of the
mountains and foothills early this afternoon. This precipitation
will continue to work its way to the coast over the next couple
hours. Have adjusted pops accordingly. Sufficient instability to
continue the threat of an isolated thunderstorm or two.

Winds have veered with time allowing for more of a westerly
component today. This will allow for the beaches to warm up
today, compared to yesterday`s gusty southerly winds off the
Gulf of Maine brink.

Prev Disc...
702 AM Update... Showers and convection are
marching southeast this morning along a frontal boundary with
some heavier downpours especially along the front edge. Ahead of
this widely scattered showers are occurring. No lightning is
reported so far but am watching cells which have very heavy rain
according to instantaneous dual-pol estimates. Minor changes to
the forecast database include temperature and dew point
updates.


Previous discussion...
Shower activity is beginning to pick up again across eastern
and northern sections of the forecast area with the approach of
a frontal system. Convection will be less focused with a pre-
frontal trough as well as a cold front crossing the region and
broad but weak instability. QPF looks light overall but there is
still the possibility of heavy downpours... especially over the
mountains...with moisture from TS Cindy lingering. A few
rumbles of thunder are possible but overall instability is weak.

Convection should exit the coast by mid-morning with the
remnants of Cindy moving offshore near Cape Cod bringing
additional showers to Portsmouth and the islands in the Gulf
of Maine. This baroclinic zone sits offshore with additional
short wave energy moving along it and producing rainfall well
off the coast this afternoon and evening. Drier air moves in
today with temperatures warming into the upper 70s to upper 80s
with gusty SW to W winds in place.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Another cold front will hang up along the Canadian border and
produce showers and scattered thunderstorms for mainly the
mountains Sunday...especially in the heat of the afternoon with
readings warming into the 70s and 80s once again. A robust short
wave approaches towards the late afternoon and evening
increasing thunderstorm activity...but earlier cloud cover and
showers will keep any strong storms from forming. Showers will
diminish in the evening with drier air arriving and the loss of
heating.

Expect temperatures to fall back into the upper 40s/lower 50s
in the mountains with mid to upper 50s to the south and east for
overnight lows.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Upper air wave pattern this weekend features a building West
Coast ridge and a broad trough over the eastern half of North
America. This is allowing the southwestern deserts to bake while
the center and eastern parts of the country enjoy cooler air
spilling down from the northern parts of Canada. New England is
in the southwesterly flow ahead of the broader Eastern trough
with frequent waves tracking through the flow sending weak cold
fronts through the region. During the first half of next week, a
trough will drop down out of the Gulf of Alaska and help to
squash the West Coast ridge to the east, in turn forcing the
Eastern trough to make a move to the east. Once it exits a broad
west to southwest flow will transport warmth from the middle of
the continent eastward into New England late in the week.

Expect gradually cooling temperatures Sunday through Tuesday as
the Eastern trough slowly pushes into the area. Several waves
within the broader trough will rotate through, with each of
these waves potentially bringing a round of showers especially
if they move through during the daytime. The best chance of
showers and possibly thunderstorms will be Tuesday when the main
trough axis crosses through New England. High temperatures will
generally be in the 70s, with lows in the 50s. After the trough
departs on Wednesday the ridge will begin affecting the area on
Thursday as warm, humid air begins to spill into the area. A
wave tracking through Ontario and Quebec will organize a warm
front to push through New England on Thursday, the leading edge
of the warmer air. Some showers can be expect along and north of
that warm front while warm, humid weather will arrive south of
it. The entire area looks to get into the warmer air by Friday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Short Term...
Pockets of MVFR conditions are occurring this morning in lower
ceilings/-SHRA and the occasional -TSRA associated with a cold
frontal passage. TS Cindy is also contributing to the moist
airmass. Fog has yet to affect RKD but is expected to affect
them briefly. Most of the dense fog is expected to remain over
eastern Maine and offshore this morning. Conditions improve to
VFR as drier air works in today on developing gusty westerly
winds. Winds diminish after sunset.

Long Term...Generally expecting VFR conditions late this weekend
through the middle of next week. However, occasional showers are
also possible especially each afternoon, mainly in the interior.

&&

.MARINE...
Short Term...SCAs for hazardous seas will continue over the
eastern outer waters this afternoon.

Long Term...Expect a general light westerly flow over the
waters through the first half of next week.

&&

.TIDES/COASTAL FLOODING...
Astronomical high tides will continue through the weekend with
the possibility of minor flooding particularly with the tide
late tonight at 12:05 AM at Portland. The astronomical high
tide will be 11.9 feet with a storm tide overnight likely
coming in between 12.2 and 12.7 feet. With little in the way of
wave action, expect only very minor issues along the coastline.
A headline of some sort will be needed today to cover this
concern.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 4 PM EDT this
     afternoon for ANZ150-152.

&&

$$
NEAR TERM...Cannon
SHORT TERM...Cannon
LONG TERM...Cempa



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