Area Forecast Discussion
Issued by NWS Caribou, ME-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCAR 210532
Area Forecast Discussion
National Weather Service Caribou ME
132 AM EDT Fri Apr 21 2017
Weak high pressure builds over the area tonight. Low pressure
will slowly drift towards the area from Ontario into Quebec
Friday and Friday night. Another low will form south of the
state on Saturday and move eastward into the open Atlantic.
.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --130 am update...
Nrn zones are in and out of low clouds and fog which is playing
havoc with temps. Updated latest hrly temps and dwpts to ingest
current obs into fcst and hv dropped mins slightly, mainly acrs
the St. John Vly, and hv raised them elsewhere where low clouds
are more extensive.
Orgnl Disc: A weak surface trough that moved over the area this
morning continues to decay and lose its identity over the
region. Meanwhile, high pressure has been building southwestward
from Labrador with a moist easterly flow. The net result has
been significant low level moisture trapped under a subsidence
inversion. This situation will continue tonight into Friday
morning for the forecast area. With nightfall, fog will reform
along with light rain and drizzle...mostly south of a line from
Houlton towards Greenville. Lows won`t drop much due to the
clouds. In terms of the next frontal system arriving Friday,
timing has been delayed a bit with the highest pops in the
afternoon. In fact, the eastern border may stay dry all day. As
a result, have raised highs to the east with some upper 40s
towards Washington County. Have used shower terminology for
areas that will be under chance pops during Friday to reflect
the more intermittent nature of precip. Further west, precip
will reach the western mountains in Piscataquis County during
the morning and locations over 1000 feet elevation will have
snow. Accumulations will be under an inch and shouldn`t cause
any travel issues with temperatures at or above freezing.
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.SHORT TERM /TONIGHT THROUGH SUNDAY/...
The model guidance is in good agreement through the near term
period. A Low over southern Quebec, with an occluded front
extending through Maine are the main weather features through
early portions of the period. Saturday morning the low will move
east into western Maine, and slowly cross the area Saturday into
Sunday morning. Sunday morning the low will move east into New
Brunswick. Higher pressure will build into the area through the
end of 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
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The extended models are in good agreement. A cold frontal system
approaching northern Maine at the start of the period will move
through Monday morning higher pressure will build into the area
and will dominate the weather through Tuesday evening. A low
along the coast of SC Monday, will deepen as it moves north
along the coast. By early Wednesday morning the warm front ahead
of the deepening low along the coast of DELMARVA will move into
the Downeast coast. Another frontal system moving east across
the central Great Lakes early Wednesday will interact with the
coast system. The GFS and ECMWF differ a bit on position but
generally agree that there will be interaction between the two
fronts. The GFS hold the coastal system along the Downeast
coast, and moves the other front east/west across southern
Quebec. The EC moves the coastal system in to northern Maine,
holding the frontal system over Canada to central Quebec.
Thursday morning these differences continue. The GFS moves the
coastal system east of Maine into eastern New Brunswick, the low
of the second front moves to western Quebec with the cold front
extending south through VT. The EC move the low front the
Canadian system to northern Maine, the front east of Maine, with
wrap around precipitation across western Maine. Higher pressure
will build into the area Friday evening and will remain through
the end of the period.
Loaded a blend to smooth out the differences in the models,
however the solution leans more towards the GFS solution. Used
NAWAVE4 for seas in the coastal waters. Used windgust by factor
.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --NEAR TERM: IFR conditions at BGR and BHB until around mid-
morning when cigs lift to MVFR as main energy is confined to the
north while brief ridge of high pressure builds into Downeast.
MVFR in -dz expected from early afternoon thru end of TAF valid
time. Further to the north, IFR will dominate early this
morning and again overnight with MVFR restrictions expected this
afternoon. Cannot rule out IFR cigs briefly scattering out
early this morning but overall expect IFR conditions to be
predominant at HUL, CAR and FVE. -SN expected after 01z at FVE
and CAR with a rain/snow mix at HUL and PQI before becoming all
-sn after 04z.
SHORT TERM: IFR conditions in rain, or a mix of rain and snow
Friday night through early Sunday morning. Higher pressure will
build into Maine Sunday morning bring clearing conditions. MVFR
early Sunday morning becoming VFR by mid morning Sunday. A cold
front will move through northern and central Maine Sunday night
bringing conditions back to MVFR for FVE, CAR, PQI and HUL. The
front will clear the area Monday morning VFR conditons will
return through the end of the period.
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NEAR TERM: Winds and seas creep up again on Friday as a low
moves towards the waters, but with the cold water temperatures
and stable conditions, will cap wind gusts to 25 kts and seas at
5 ft at this time. If confidence in SCA issuance increases
tonight, then we`ll issue the advisory for Friday into Friday
SHORT TERM: Winds and seas will be just below SCA criteria
early in the period, then subsiding.