Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 302225
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
625 PM EDT TUE AUG 30 2016

.SYNOPSIS...
A weak cold front will approach from the north overnight and will
slowly sag south into northern New England on Wednesday. The front
will gradually sink south into central New England Wednesday night
and will shift offshore by late on Thursday. High pressure will
gradually build in from the west Friday through Saturday and will
hold over the region into Monday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
625 PM Update...Little change to the going forecast at this time.
Have adjusted a few of the forecast elements a little bit based on
latest trends in observational data as well as new mesoscale model
data. A dry evening should continue to be had. Any scattered
shower activity should hold off until after 4-5am across the
northern zones.

Previously...

Slow moving cold front will approach from the north overnight as
high pressure shifts off to the east. Not a lot of forcing along
this boundary but will include some low chance pops for scattered
showers mainly after midnight in northern zones. Remainder of the
forecast area will just see variable high clouds. Lows overnight
will be somewhat warmer with readings generally ranging through
the 50s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Front will sag into northern New England on Wednesday increasing
the chance for showers in Northern and central portions of the
forecast area. Fair amount of high and mid level cloudiness will
hold down heating but may generate enough CAPE to pop off some
isolated thunderstorms during the afternoon in the mountains and
foothills. Highs will top out in the mid 70s to lower 80s in the
north. Warmest areas will be in southern New Hampshire where highs
will reach the mid to upper 80s. Southwest flow will cap highs in
the upper 70s to lower 80s from Portland to the mid coast.

Front will continue to slowly sag southward Wednesday night
producing scattered showers throughout the forecast area
overnight. Lows will range from the mid 50s north to the mid 60s
south.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Chance of high impact WX: Minimal at this time, but watching
tropical systems to our south late in the period.

500 mb pattern continues to shift from a trough in the eastern
CONUS at the start of the long range to building the western
Atlantic ridge early next week, the only question is will there
be a closed low to our south, as a result of synoptic-tropical
interactions.

Regarding sensible weather early in the forecast period, models
continue to show significant positive tilting to the trough as it
moves into northeastern US Thursday. This would slow the progress
of the front as it aligns with upper flow and weak wave develops
alongthe front. The dynamics are great with this wave but will
keep chc pops in the forecast, especially near the coast, into
Thursday, which means more clouds and lingering higher humidity
until the front pushes through late in the day, with some clearing
Thursday night.

Honestly its after this point where we have to start to thinking
about those tropical-synoptic interactions and how they are
usually poorly represented in larger scale models, but by Friday
the troughing over the eastern US and what is now TD 9 do begin
their interaction, which according to both the 12Z GFS and the
Euro will be a long and involved relationship. Some good news is
that it looks like Friday and Saturday will keep the system far
enough south for some ridging to work in over the top of the
closing low, and cooler drier will work in with partly to mostly
sunny skies. By Sunday could start seeing the effects of this
system with some cirrus rolling in, but also should be dry and
starting to warm up a bit as flow shifts to the SW.

At this point, will be sticking with a persistent dry forecast
for Monday and Tuesday. However, will watch how the trough and the
tropical system interact. Interesting to note that both models do
allow the trough and the tropical system to merge into one closed
system south of New England, which would stall the sfc low or pull
it back west before the closed system fills and tracks N-NE. Given
the current forecast there would be greater impact to our south,
but still there is a low probability at this point to see some
wind or rain the CWA around Mon or Tue. One thing it would do
passing to our south is produce enough swell to bring back the
risk of rip currents by Monday.  Again, confidence remains low
with this this system, which could have little or no effect on
weather.

&&

.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
Short Term...VFR tonight and Wednesday. Areas of MVFR/IFR ceilings
Wednesday night.

Long Term...Possible tempo flight restrictions in SHRA on
Thursday, but otherwise VFR thru Saturday.

&&

.MARINE...
Short Term...Long period swell of 3 to 5 feet will continue to
affect coastal areas through wednesday night...but should not be
an issue for small craft. This will likely keep the rip current
risk elevated through the period.

Long Term...Winds and seas should dissipate by Thursday, and stay
below SCA lvls through Sunday. Will have to watch progress of TD
9, currently in the Gulf of Mexico as it moves NE into the
Atlantic, and could bring swell back into the waters by Sunday,
and even has the potential for SCA as well.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$
SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...
LONG TERM...Arnott
AVIATION...Arnott
MARINE...Arnott


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