Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
318 PM EST Friday Dec 26 2014
high pressure will hold south of New England through tomorrow. A
cold front will approach from the west tomorrow night and will
cross the region on Sunday. Colder high pressure will build in
from the west Sunday night through Wednesday.
Near term /through 6am tomorrow morning/...
a ridge of high pressure continues to build over the region and
with the weakening pressure gradient we will see winds dropping
off this afternoon. Moderate northwest flow aloft has made a definitive
line of upslope clouds in the mountains and most clear skies in
the downsloping to the southeast of the mountains. Warm
temperatures will continue through the night and even though areas
with clear skies will see the greatest radiational
cooling...temperatures will only drop into the low 30s to upper
Short term /Saturday through Sunday morning/...
ridging overhead with t850 climbing to +5c by late Saturday
evening as flow shifts to the southwest will keep our temperatures well
above average again tomorrow. Since the winds aloft will not
switch to the southwest until late in the afternoon...we will
still see some upslope clouds across the mountains tomorrow and
even a light snow shower will be possible. Downsloping southeast
of the mountains will make for another great day in these areas.
A weak cold front will start to move into the area late Saturday
night into Sunday morning. This front is starving for moisture
however...and not expecting more than just a few scattered
showers...mainly across the northern forecast area.
Long term /Sunday through Friday/...
early sun cold fnt crosses the region. Flow is fast and forcing
looks fairly sheared out...so I do not expect much in the way of
precipitation with the frontal passage.
It will usher in a stable and much cooler pattern for the
foreseeable future. The highlights are rising heights and ridging
building through Alaska and into the Arctic. Also persistent troffing is
forecast in the southwestern Continental U.S.. all the while southeastern Continental U.S. Ridging tries
to hold firm...with little blocking in the northern Atlantic. The
-epo /ridging through Alaska/ should provide Canada and the northern tier
states will plenty of colder air. Certainly much colder than the
current period. Therefore temperatures are mainly near to below normal
through the entire long term. There is a bit of uncertainty
there...and it extends into precipitation chances as well. The -pna
/troffing in the western Continental U.S./ Will keep shortwave troughs ejecting towards
the northeast. The southeastern ridge and low heights across Canada will
keep flow progressive. And finally lack of blocking will allow any
storm systems that do develop to have the possibility of cutting
to the west. This could firstly sneak some warmth into the area late
in the period. Secondly...this will create a bit of havoc in the
model guidance regarding key shortwave troughs and timing. It is likely
we will see timing difference of a day or two between models...as
well as differing degrees of amplification. Tried to keep some
pop in the mountains to account for these fast moving shortwave features. In
addition...I did knock down pop in the far ranges of the extended
to high chance...as despite good agreement today the European model (ecmwf) and GFS
will likely waffle on solutions beyond day 5 in the coming days.
In short the long term looks fairly active...with plenty of precipitation
chances through the New Year. Cold air will be available...but that
doesn/T mean slam dunk snowfall in every system either. Basically a
return to more normal winter conditions.
Aviation /20z Friday through Wednesday/...
short term...VFR conditions should persist today through
Saturday with possibly some MVFR conditions in the persistent northwest
flow causing upsloping clouds. High pressure moving off the East
Coast will dominate our weather through Saturday. A cold front
moving into the area late Saturday night and early Sunday morning
may bring a few areas of MVFR conditions.
Long term...frontal passage occurs sun with mainly VFR conditions expected.
Isolated MVFR or lower is possible in a passing rain showers or shsn...before
conditions improve to VFR across the entire area. There is a small
chance that westerly flow may lead to more in the way of cloud cover
than currently forecast for the mountains through midweek.
short term...the pressure gradient has eased this afternoon as a
ridge of high pressure builds into the area. Expecting Small Craft Advisory
conditions due to mostly to seas in the 5 to 6 foot range from the
long westerly fetch to drop off this evening. After that we will
have high pressure overhead and most likely stay below Small Craft Advisory
conditions through early Sunday morning depending on the timing of
the cold front pushing through.
Long term...marginal Small Craft Advisory conditions are possible behind cold fnt
sun...in westerly flow. After that high pressure builds over the waters and
winds and seas will remain below Small Craft Advisory thresholds.
Marine...Small Craft Advisory until 6 PM EST this evening for anz150.