FXUS61 KCAR 210228

Area Forecast Discussion
National Weather Service Caribou ME
1028 PM EDT Tue Mar 20 2018

High pressure over Hudson's Bay will dominate area weather until
late Wednesday. Low pressure will track from the Mid-Atlantic
coast towards Nova Scotia Wednesday night into Thursday. High
pressure will gradually build from the north during the weekend.


1030 PM Update...
Satl imagery continued to show clear skies across just about all
of the CWA w/the exception of the immediate coast as high clouds
stream ne. Adjusted the hrly temps bringing them up overnight
blending in the HRRR to initialize. The HRRR looked like it had
a good handle on showing the low lying areas getting down to the
single numbers. Some sites back across the nw areas could see
near 0F. Winds will dropping off this evening and will continue
to do so overnight as high pres ridges in from the w as shown by
the latest analysis.

Previous Discussion...
1028mb sfc high sitting ovr Ontario wl continue to bring nrly
flow to the CWA tonight.

Coastal low dvlpng off the mid-Atlantic coast wl strengthen
ovrngt as another vort max reinvigorates sfc low dvlpmnt late
tonight. This wl result in sfc winds veering to the northeast
and increasing as pressure gradient tightens drg the aftn Wed.

Skies wl be clr tonight with high cirrus beginning to mv into
coastal zones aft 12z in the mrng. Expect that nrn areas wl rmn
mostly sunny until late aftn. With most of the CWA still seeing 12+
inches of snow on the ground expect that under clr skies and winds
gradually bcmg light ovrngt hv significantly undercut guidance acrs
all locales. Mins for tonight wl drop to nr 0F acrs the North Woods
in normally cldr vlys and m/u teens along the coast. Maxes on Wed wl
settle out right arnd normal values with pcpn likely holding off
until vry late in the day.


On Wednesday night, the vertically stacked low off the Delmarva
coast will send an its wraparound occlusion towards the
coast...accompanied by a shortwave rotating around the closed
upper low. At the same time, the entire closed upper low will
drift northward towards Nova Scotia Wednesday night into
Thursday. While the occlusion will be weakening and the surface
low will be well offshore, moisture wrapped around the upper low
in the trowal could affect the Down East region Wednesday night
into Thursday morning. This will be an all-snow event, with the
possible exception of some sleet along the immediate coast due
to warm air aloft in the occlusion. Of note is a strong
northeasterly H900 jet coinciding with occlusion and potential
for some elevated instability. This could generate some heavier
snowfall towards the coast on Wednesday night into Thursday
morning. The Down East region stands the best chance of advisory
or warning level snowfalls from this system and the Allagash
would likely receive no snow as amounts taper to the NW.
Ultimately, snowfall amounts and duration will be based on the
exact track of the upper low, but the current trend is pushing
the upper low towards Nova Scotia with resulting reductions in
snowfall towards Aroostook County. The ECMWF has moved towards
the GFS solution, but interestingly, both the high-res GEMS
regional and the NAM remain further west and have not totally
disregarded these in the forecast blend. The LLJ will help
create surface wind gusts over 30 mph...and possibly up to 40
mph Wednesday night into Thursday. Thus blowing snow will be a
threat and have maintained mention in the forecast. Furthermore,
the winds could generate a storm surge along the coast that
could cause some minor coastal flooding. Thursday night into
Friday, guidance is in decent agreement with regard to the upper
low pulling away into the Canadian Maritimes, weak ridging over
the area and a north to northwest flow. This probably means a
lot of cu and stratocu and a few flurries. Have used NAM/GFS
925-850 moisture fields for Friday's cloud forecast.


On Saturday into Sunday, upper level low pressure will crossing
the area from north to south and eventually become a nearly
stationary vertically stacked upper low over the Atlantic early
next week. Meanwhile, a powerful upper ridge will build eastward
over the area Sunday night into Tuesday. Expect generally mostly
cloudy skies over the area with some snow showers for the
weekend and highs in the 30s. The ridge will bring warmer
temperatures and clearing skies for early next week...and may
even persist through much of next week depending on how closed
upper low over the Atlantic evolves. Expect 40s over the entire
area by next Tuesday, but snowmelt should be controlled with
very dry air and overnight lows below freezing.


NEAR TERM: VFR next 24 hours. Gusty nw winds will die off around
00z tonight before veering to nerly in the morning.

SHORT TERM: IFR to LIFR conditions in snow will affect BGR and
BHB later Wednesday night and continue into Thursday morning.
The IFR conditions may briefly reach as far north as PQI late
Wednesday night and early Thursday. After this snow event moves
out, the prevailing conditions will vary between MVFR cigs and
VFR Thursday afternoon through Sunday.


NEAR TERM: Winds increase ahead of strengthening low pressure
system moving along the eastern seaboard very late on Wed. Have
issued Gale Warning for all waters beginning 20z Wed thru the
end of the pd.

SHORT TERM: The Gale Warning will continue into Thursday
afternoon and transition to an SCA. Another SCA is probable
Saturday night into Sunday.


MARINE...Gale Warning from 4 PM Wednesday to 4 PM EDT Thursday for



Near Term...Hewitt
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