Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 292353
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
753 PM EDT SUN MAY 29 2016

.SYNOPSIS...
A front stalled to our south will return north as a warm front
early Monday. This front will be preceded by showers and a few
thunderstorms through Monday morning. A warm humid air mass will
follow the warm front on Monday afternoon with another round of
showers and thunderstorms expected. Tropical moisture from the
remnants of Bonnie will be entrained in the frontal system and
could produce heavy rainfall and localized drainage flooding on
Memorial day. Two cold fronts will cross the area Monday and
Tuesday night with high pressure and drier air to follow Wednesday
and Thursday. An upper level trough could produce some rain FRiday
or Saturday.

&&
23z update...
Showers and a few thunderstorms currently edging into the
Connecticut Valley early this evening and showers continue in far
northern new hampshire and far northern Maine zones. Showers
having a tough time getting into southwest New Hampshire where
marine layer is well entrenched but a few sprinkles will be
possible in this area through midnight. Remainder of the forecast
area generally covered in lowering ocean stratus in southern and
eastern New Hampshire and much of southern and central Maine.
Expect more organized showers and some thunderstorms to move east
through the region ahead of a pre-frontal trough toward daybreak.
Have adjusted temp/td/sky/pop and wx grids to reflect current
trends and surface obs. No other changes planned attm.

&&

Previous discussion...
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
At 18z a 1005 millibar low was centered over the upper Great
Lakes with a warm/stationary front extending southeast through
southern New England. To the north of this frontal boundary...
easterly flow persisted with extensive low cloud found across the
forecast area. With the exception of the upper Connecticut valley...GOES
visible imagery showed broken to overcast conditions across the
forecast area. NWS doppler radar mosaic showed a broken area of
convection along and to the north of the 850 millibar warm front
with activity impacting northern and mountain sections at moment.
Additional activity over western New England could reach the
Connecticut valley this evening. For tonight...the stalled front
begins to push northward...but it won`t clear most of our northern
and eastern forecast area until tomorrow afternoon as southwest
flow in the low levels increases towards dawn. Convection will
gradually increase in coverage overnight as overrunning increases.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As mentioned above...the warm front will work north and east
across much of Maine and extreme Northern New hampshire on Monday
morning leaving the entire forecast area in the warm sector by
monday afternoon. Monday morning will feature an area of showers
and thunderstorms that will push north and east and taper to
scattered showers and thunderstorms following the warm frontal
passage. we`ll warm into the 70s...with the exception of midcoast
Maine because of the onshore trajectory...and it`ll be a humid day
with dewpoints rising into the 60s. We should see sufficient
heating from the Connecticut valley northward through the Maine
mountains and foothills for scattered showers and thunderstorms to
developing during the afternoon ahead of the cold front. Locally
heavy rainfall will be possible as tropical moisture from the remnants
of Bonnie will be entrained into the frontal system. A few of the
stronger cells could also produce gusty winds. Any lingering
convection will end by late Monday evening as the cold front
sweeps offshore. Low level moisture and clearing skies should
result in areas of fog Monday night behind the departing frontal
system.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
high impact wx: none expected.

Models continue to trend toward a more zonal jet that will reside
just n of the US/Canada border. Will see one low wave exiting at
the start of the long range, and another moving in at the end of
the week, with ridging in between. Although 850 mb temps will
generally be above normal, a lack of decent low level flow will
allow onshore flow to develop, and keep sfc temps closer to
normal, or even below normal, along the coast.

The warmest day will be Tuesday, as will have to wait for upper
level trough to drag the secondary cold front through the CWA,
which will lower humidity and cool things down a bit. Still, highs
on Tuesday will be in the upper 70s to mid 80s. Might see a few
showers or storms across the far nrn zones...but weak dynamics and
lack of instability should prevent much else from happening with
the fropa.

Wednesday and Thursday should be fair. Both days will feature a
sea breeze, but Thursday will see the marine lyr move further
inland as there will be an onshore pres gradient. Highs Wed will
be from 70-80, and on Thursday mid 60s on the coast to mid-upper
70s further inland. Overnight lows Wed and Thu night will be in
the mid 40s to mid 50s, fairly close to normal.

500 mb trough approaches from the west Friday and moves into New
England on Sat. Models are lingering remnant tropical system off
the Carolina coast through most of the week before it gets picked
up by that trough. A lot of what happens with the front will
depend on that, and confidence is low in this regard. Have chancepops
in the forecast for Fri and Fri night, but just kept slight for
Sat, which leans toward the ECMWF.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Short Term /through 12z Tuesday/...MVFR and LCL ifr tonight in
ceilings and fog along with sct -shra/ and isold -tsra. On
Mon...conds improve to vfr throughout btw 12 and 16z following a
warm frontal passage with areas of mvfr btw 18z and 02z Tue in
shra/tsra. Areas of MVFR and lcl IFR aft 06z Tue in valley stratus
and fog.

Long Term...Mainly VFR, with the exception of possible vly fog
Wed and Thu night.

&&

.MARINE...
Short Term /through Monday night/...winds and seas expected to
remain below SCA threshold. However...there will be periodic vsby
restrictions in fog, haze, and thunderstorms through Monday
evening.

Long Term...May see some winds approach SCA Tuesday afternoon, but
otherwise, fairly quiet on the waters through the rest of the
week.

&&

.FIRE WEATHER...
Cool...onshore flow will dominate most of the area into tonight.
Relative humidity values will remain moderate to high region-wide.
On Mon tropical moisture associated with Bonnie will stream into
the area. Showers are likely...with some possibly heavy at times.
A wetting rain looks most likely across southern areas.

&&

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

&&

$$



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