Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 020339
Area Forecast Discussion
National Weather Service Gray ME
1039 PM EST Thu Dec 1 2016
Low pressure will exit into the maritimes by early evening. In
the wake of this disturbance, northwesterly flow will continue
through the start of the weekend with snow showers in the northern
mountains. Cold high pressure will settle in for the start of next
week. Light overrunning precipitation could arrive Wednesday or
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Update...Only minor changes to reflect latest observational
trends. Albeit more difficult with darkness...webcams from our Nrn
zones do show continuing signs of precip falling. So PoP was
bumped up slightly again. Otherwise...no major changes.
Previous discussion...at 19z...a 990 millibar low was over the
downeast Maine coastal waters. An occluded front extended
northwest from the low to a second 991 millibar low over western
Quebec. NWS doppler radar mosaic showed scattered convection over
the northern half of New Hampshire...otherwise precipitation had
exited the area to our north and east. In the westerly flow behind
the departing disturbance GOES imagery showed some partial
clearing over eastern New Hampshire into adjacent western Maine.
The cool westerly low level flow off the Great Lakes was
transporting moisture into the higher terrain and should keep
broken clouds across much of the Connecticut Valley northward
through the international border area the remainder of today and
tonight along with scattered rain or snow showers. There could be
some light snow accumulations tonight across the higher terrain.
Elsewhere...we should see scattered to broken clouds. Lows tonight
should be in the 30s.
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.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Little change to sensible weather Friday and friday night with the
surface and upper lows remaining just to our north over Eastern
Canada. The cool cyclonic flow and a low level trajectory off the
Great Lakes should keep Connecticut Valley and the higher terrain
of New Hampshire and western Maine mostly cloudy with a few rain
or snow showers. Some light snow accumulations will remain
possible across the higher terrain as well. Elsewhere...we`ll see
partly cloudy conditions. highs tomorrow will range from the 35 to
40 in the mountains with 40s elsewhere. Lows tomorrow night will
range from the upper 20s to lower 30s.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Cold cyclonic flow will start the long term period off - Saturday
and Saturday night. Variable clouds are expected downwind of the
mountains in a downsloping regime but upslope clouds and snow
showers expected in the mountains. Saturday could be a bit breezy
too - adding more chill to the air. Same general pattern holds for
Sunday except the upper low moves off to the east and allows for
lighter winds and more sunshine.
A weak short wave trough will likely approach from the west for
Monday. However, this trough will be dampening with time. By the
time it gets there moisture and forcing will be limited - so we
just went with a slight chance of snow showers. May end up just
being flurries if anything.
High pressure then settles overhead for Tuesday. Thereafter,
forecast uncertainty is high and confidence in sensible weather is
low come Wednesday and Thursday. Some model guidance over the last
few days has pointed toward a coastal low possibly bringing a good
shot of wintry precipitation during this time. However, there is
considerable spread on how the upper air pattern over NOAM
evolves, as well as the handling of an important short wave trough
ejecting out of Mexico. Have not been able to see the 12z ECMWF as
it is running late.
00z ECMWF and GFS ensemble guidance generally points toward a
much more tame scenario with many members keeping any significant
low pressure center well south of the region and leaving us with a
period of light overrunning precipitation - if anything- instead.
Again, low confidence forecast, but at this time it seems prudent
to hedge toward the drier models until distant short wave troughs
become better sampled.
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Short Term /Through Friday Night/...VFR...xcp lcl MVFR psb in Mtn
Long Term...MVFR conditions are expected in the mountains Saturday
into Sunday morning with VFR conditions expected downwind from the
mountains. A period of MVFR conditions is possible Monday in a
little light snow - but probability is pretty low. VFR returns
Short Term /Through Friday Night/...Small Craft conditions linger
tonight in westerly flow across all the waters. It`s likely we`ll
see Small Craft conditions persist through the day Friday outside
Long Term...A period of SCA conditions are possible on the ocean
waters Saturday and Saturday night - possibly into early Sunday.
MARINE...Small Craft Advisory until 7 AM EST Friday for ANZ150>154.