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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 161948

Area Forecast Discussion
National Weather Service Caribou ME
348 PM EDT Sun Jun 16 2019

Low pressure will form along a stalled frontal boundary in the
Gulf of Maine tonight and move eastward into the Canadian
Maritimes Monday. High pressure builds from Quebec Monday into
Tuesday night. A front will stall over southern New England
Wednesday and Thursday, with waves of low pressure riding along


A wave is currently propagating eastward along the stalled
frontal boundary in the Gulf of Maine. This wave will spread
rainshowers along the coast this afternoon into the evening, 
but shouldn't spread any further northward than the Bangor area.
Very humid air is moving eastward and along the boundary and 
will be drawn northward as another cold front moves towards the 
coast this evening. This means fog will develop along the coast 
this evening and will spread northward towards Bangor as well as
interior Hancock and Washington counties. As this cold front in
the northern stream phases with the stalled front in the Gulf 
of Maine...and an upper level shortwave rotates southward from 
Quebec, cyclogenesis will occur in the Gulf of Maine. However, 
this low will quickly exit eastward into the Canadian Maritimes 
tonight into Monday and precip will only amount to around a 
maximum of a tenth of an inch along the Hancock County coast. 
The main effect of the low will be to pull dry Canadian air 
southward and clear out the fog by later tonight. High pressure 
will build southeast behind the low through Monday and ensure 
dry conditions and seasonable temperatures. There will be 
sufficient H850 moisture for fair wx cumulus across for most of 
the area. 

The region will be under locally zonal flow aloft Monday night-
Tuesday night. With no significant shortwaves forecast to be
embedded int his flow during this time range, it should be dry,
with partly to mostly clear sky conditions. Temperatures should
be near to slightly above normal.

A weak 700-500 hPa shortwave approaches Wednesday afternoon. So
while the morning should be dry, there could be some isolated 
to scattered showers Wednesday afternoon. The best chance for 
any showers will be over the Northern Maine. Highs on Wednesday 
should be near to slightly above normal.


A northern stream trough approaches Wednesday night, with the
best chance for any showers once again over the North.

The models then differ with where and when this northern stream
trough phases with the southern stream. The ECMWF is slower with
the eastward profession of the northern stream trough across SE
Canada, so phases it with the southern stream sooner, resulting
in a more unified and progressive push of the southern stream
short wave off the eastern seaboard. The GFS is a bit quicker to
push the core of the northern stream trough east, resulting in a
more E-W strung out tail to the trough, so it phases later with
the southern stream (and is less progressive in passing it
offshore as a result). The CMC is similar to the ECMWF in its
timing. As a result, have leaned towards the ECMWF/CMC from
Thursday through Saturday.

A shortwave trough pushes through on Thursday, ahead of the main
northern stream trough. This should trigger some scattered
showers over the region. With only a few hungered J/kg of CAPE
progged and Showalter Indices generally 4 or higher, have left
thunder out of the forecast for now.

As the streams phase, a coastal low should develop Thursday 
night and reach the vicinity of Southern New England/Long Island
by Friday morning, spreading rain over at least the southern
half of the CWA and possibly into the North as well. This low
should then track to south of Nova Scotia by Friday evening, as
the phased trough slides offshore. Rain chance s should diminish
from NW to SE over the area on Friday as a result. It should be 
dry Friday night, but have slight chance pops in in case a GFS 
like solution ends up occurring.

The axis of the northern stream trough passes through on
Saturday, so should see some scattered showers with that.

Deep layered ridging builds in Saturday night and Sunday, so it
should be dry.

Temperatures should be near to a few degrees below normal
Wednesday night-Sunday.


NEAR TERM: All sites will remain VFR except towards the coast
where fog and low clouds will be an issue. BHB, Machias and
Eastport will have fog rolling in this evening, but the fog will
exit by daybreak. The fog will move far enough north to affect
BGR for several hours later this evening into the night.

SHORT TERM: There is a chance for MVFR or lower conditions
Downeast Tuesday night. It should then be VFR on Wednesday. 
MVFR or lower conditions are then possible again Downeast
Wednesday night. MVFR conditions are possible Thursday with any
showers, otherwise it should be MVFR. IFR or lower conditions
are probable Downeast and Bangor Thursday night and Friday and 
MVFR-IFR conditions possible farther north.


NEAR TERM: Fog is the primary concern for this afternoon through
the night as humid air moves over the cold waters. Fog will 
exit the waters late tonight into early Monday morning as drier 
air arrives from the north.

SHORT TERM: Winds should be around 10 kt or less from Monday
night-Friday over all waters. As a result, sub-SCA conditions
are likely during this time frame. However, depending on the 
exact track and strength of a possible coastal low tracking to 
the south late this week, there is a low chance for SCA 
conditions on the coastal ocean waters by Friday.



Near Term...MCW
Short Term...Maloit
Long Term...Maloit