Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 182337

Area Forecast Discussion
National Weather Service Caribou ME
637 PM EST Wed Jan 18 2017

Low pressure south of the Gulf of Maine will track out to sea
tonight. An upper level disturbance approaching from Canada will
cross the area late tonight into Thursday morning. High pressure
will build into the region on Friday and remain across the area
into early next week.


600 PM Update: PoPs were adjusted to reach 100 percent across the
Nrn hlf of the FA durg the late ngt to erly morn hrs based on our
fcst 6hrly QPFs/SNFLs late tngt, suggesting a lgt, but imminent
lgt snfl event, with the PoP from QPF near term tool used for this
adjustment. Otherwise, minor adjustments to fcst hrly temps/dwpts
thru the ovrngt based on late aftn/erly eve obsvd temps, with no
chgs to fcst ovrngt lows attm.

Orgnl Disc: The low which brought some light snow Downeast will
slide out to sea well south of Nova Scotia tonight. A separate
upper level wave will approach from the northwest tonight bringing
a period of snow late tonight into early Thursday morning. The
snow will be produced as a function of divergence aloft and some
surface convergence ahead of the shortwave. Starting times will be
around midnight over the north and a few hours after midnight
Downeast. Snow will gradually taper off early Thursday morning.
Amounts will range from around 3 inches north to an inch or less
Downeast. The sky will remain mostly cloudy on Thursday with highs
a few degrees above normal as high pressure builds in from the


The models are in good agreement through the period. A high
pressure ridge builds into Maine from the west as an Upper level
low over eastern Quebec continues to move away from the area. A
low move through northern Quebec with a trough extending south to
northern Maine early Saturday morning may product a few
snowshowers across the crown of Maine Saturday morning, otherwise
high pressure will dominate the weather through the period.

Loaded a blend of the GFS/GEM/NAM/ECMWF to smooth out the minor
differences in the models. Loaded NAWAVE4 for seas in the coastal
waters. Loaded windgust by factor tool. For QPF used GFS.


The extended models are in good general agreement at the start of
the long term. A high pressure ridge over the area will begin to
build to the east of the area as a low over Lake Superior and a
low moving north along the Atlantic coast begin to put pressure on
the western edge of the ridge. By Monday morning the frontal
system associated with the lows will move into southwest Maine. By
early Tuesday morning the warm front moves to Downeast Maine. By
Tuesday morning the models start to diverge a bit, with the ECMWF
moving the low to eastern Lake Huron and a secondary low over
Portland, The GFS shows the low remaining over Virginia Beach.
Both models show an occluded frontal boundary over Maine. Tuesday
evening the GFS shows signs of secondary development over
Portland, the ECMWF moves its low east to the Bay of Fundy. Both
models continue to show the occluded frontal boundary over Maine.
Wednesday morning both models show the main front east of Maine
with northern Maine remaining in wrap around precipitation. The
GFS builds a ridge in for the remainder of the period, while the
ECMWF maintains the wrap around precipitation through the end of
the period.

Loaded a blend to smooth out the minor differences in the models.
Loaded NAWAVE4 for seas in the coastal waters. Loaded windgust by
factor tool.


NEAR TERM: VFR conditions this evening will lower to IFR from
north to south in snow late tonight. IFR conditions on Thursday
will improve to MVFR around midday across the region as snow
tapers off and some clouds remain.

SHORT TERM: VFR conditions all all sites through the period. FVE
and CAR may see a few snowshowers Saturday and again Sunday adding
HUL to the chance snowshowers. These snowshowers will bring vsby
and cigs down to lower MVFR, but these snowshowers should be brief
and vsby and cigs will return to VFR quickly after the shower


NEAR TERM: An SCA will remain up early this evening for the
offshore waters for wind gusts above 25 kt and seas over 5 ft.
Winds and seas should diminish and subside overnight.

SHORT TERM: High pressure will dominate the weather for the
coastal waters, winds and seas below SCA criteria through through
the period.





Near Term...VJN
Short Term...Norton
Long Term...Norton
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