Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
644 PM EST Thursday Jan 29 2015
low pressure will organize off of the Massachusetts coast Friday
morning and intensify in the Gulf of Maine late Friday. The low
will then slowly move into the Canadian Maritimes Saturday. High
pressure builds toward the region from the west Sunday into
Near term /through Friday/...
update 1840 est: no major changes... have adjusted temperature..
wind and dew point.
High pressure continues in control tonight with enough clearing to
drop temperatures back to the single digits except in the western
zones where high clouds will thicken this evening. Lows for
tonight will before midnight for most locations. The high clouds
continue to build after midnight with temperatures rising.
Temperatures will rise quite sharply down east with the southerly
flow onset...reaching near 30f by daybreak. A clipper system
approaches with light snow hitting western zones towards daybreak
and slowing spreading east over the course of the morning and
early afternoon. The clipper will be arriving out of Quebec...but
expect redevelopment of the low off the eastern mass coast Friday
morning. An inverted trough will extend northward from this
intensifying low into the western edge of the forecast area.
Heavier snow will start to break out along this convergence line
from southern Piscataquis County northward to the Allagash. Areas
under this line may receive up to 5 inches by evening while areas
along the eastern border may only have an inch or two by evening.
Snow ratios and instability aloft could cause even higher totals
along the inverted trough.
Short term /Friday night through Saturday/...
as the low deepens in the Gulf of Maine...the focus will shift
from the convergence along the inverted trough to the evolving
trowal and deformation zone. This will impact Bangor and down east
Friday night with heavy snowfall likely. The deformation zone and
associated heavy snow bands will shift gradually northward in
eastern Maine later Friday night into Saturday. Winds become a
big factor as cold air wraps into the system during Saturday.
Expect a lot drifting and blowing snow...creating another very
difficult day for motorists. Whiteout conditions may occur as the
snow will be light and easily lifted. Snow ratios look high with
good dendritc growth...accumulations will be reduced by the strong
winds. But have adjusted quantitative precipitation forecast totals towards the latest European model (ecmwf) run
that shows a very robust trowal affecting the area all day. Have
increased snow totals to 14-18 inches across the southern half of
the forecast area with lower amounts towards the County. Highs on
Saturday will be in the morning with sharply falling temperatures
and subzero wind chills across the entire area by late afternoon.
Long term /Saturday night through Thursday/...
the model guidance is in good agreement at the start of the near
term period. A low south of central Nova Scotia...with a secondary
low over the Gulf of St Lawrence. Will continue to move east. A
high pressure ridge digs south from northwestern Canada and will ridge
across the region early in the period. By early Sun morning a new low
pressure system over eastern Texas with a frontal system extending NE
into the Ohio River vlly...high pressure continue to dominate the weather
for Maine. By the end of the period the ridge will remain ridged
across Maine...the low will move NE into southern Kentucky...the warm front
pushes off the coast of Virginia.
Loaded a blend of NAM/GFS/ECMWF/Gem for hrly T/dp/wnd/pop/ski.
Loaded nawave 4 for seas in the coastal waters. Added 15 percent
to winds for gusts over land...30 percent over the coastal waters.
At the start of the period the extended models are in good
general agreement. A Canadian high pressure system will dominate
the weather at the start of the period. There will be a low over
southern Kentucky...with a warm front extending east through Virginia into the
North Atlantic. By Monday morning the GFS moves the low into the
coastal waters of Virginia along the coast of Delaware-Maryland-Virginia. The European model (ecmwf) is
similar with the low on the coast of VA/NC. By Monday evening both
models take the low NE south of Nova Scotia...east of Long
Island...wrapping the precipitation shield around the low into the northern Gulf
of Maine. By Tuesday morning the low will be well east of the area over
the Canadian Maritimes...maintaining the high pressure ridge
across the area. Tuesday morning...a new low pressure system moves east
out of western Canada into the Hudson Bay area...the GFS indicates a
secondary low over Lake Superior...both the GFS and European model (ecmwf) indicate
a low over Iowa. By Tuesday evening the low moves to the east of Hudson
Bay...the front move into southern Quebec. Wednesday morning the front moves
into central ME. Both models show a secondary low over Lake Huron.
Wednesday evening the low over Lake Huron deepens and moves NE to southern
Quebec...the cold front moves to eastern Maine. Thursday morning the GFS
moves the low into eastern Quebec...move the front to eastern New
Brunswick...with a trough of lower pressure extended SW from the
low across northern Maine. The European model (ecmwf) moves the low over Quebec
city...develops a secondary low over the North Atlantic well east
of New Jersey. By Thursday evening both models build the Canadian high across
the area...that will dominate through the end of the period.
Loaded the superblend...nawave 4 for seas in the coastal waters.
Added 15 percent to winds for gusts over land...30 percent for
gusts over the coastal waters.
Aviation /00z Friday through Tuesday/...
near term: VFR is expected until later tonight. MVFR ceilings will
move into bhb and bgr before midnight and move
northward...reaching fve by early Friday morning. All sites will
become IFR in snow during the late morning and continue to
deteriorate to LIFR by late afternoon...especially for bgr and
bhb. LIFR will be the prevailing condition all of Friday night at
Short term: IFR to LIFR in snow is anticipated all day Saturday
with blowing and drifting snow. North wind gusts will likely
exceed 40 miles per hour by afternoon.
A few lingering snow showers are expected across north and eastern
Maine Sat night. MVFR skycon...except brief IFR conditions early
during snow showers. Skycon will clear off by midnight as the high
pressure ridge builds across the area.
near term: winds will increase to Small Craft Advisory levels Friday afternoon and
continue increasing Friday night towards gale intensities. Have
issued a gale watch for later Friday night into Saturday.
Short term: gale force northerly winds will continue through
Saturday and Saturday night as the storm system moves into the
Maritimes. A Gale Warning will likely be required Sat evening...followed
by a small craft after midnight Sunday morning...through the
ME...Winter Storm Warning from 7 am Friday to 7 PM EST Saturday for
Winter Storm Warning from 4 am Friday to 1 PM EST Saturday for
Marine...gale watch from late Friday night through Saturday evening for