Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Gray ME
921 am EST Friday Feb 27 2015
high pressure will build in from the west today through Saturday
and will shift offshore south of New England on Sunday. A weak
area of low pressure will move in from the west Sunday night and
will quickly shift east of the region on Monday. High pressure
will build in from the west Monday night and will crest over the
region on Tuesday before moving offshore. Low pressure will move
northeast out of the southern Great Lakes Tuesday night and will
pass northwest of the region on Wednesday and Wednesday night.
Near term /through tonight/...
update...only a few minor changes to the forecast to account for
current observational trends.
Previous discussion...high pressure building in from the west
today will gradually clear cloud cover through early afternoon
from north to south. Despite afternoon sun...high temperatures will only
range through the teens north to lower 20s south.
Short term /Saturday/...
clear skies and light winds will once again allow temperatures to
plummet tonight. Lows will range from 10 to 20 below north to 5
above to 10 below south.
Saturday will feature scattered clouds in the mountains and plenty
of sunshine elsewhere. Temperatures will moderate slightly but
will still remain well below normal. Highs in the north will be in
the middle teens to lower 20s and lower to middle 20s south.
Long term /Saturday night through Thursday/...
models suggesting just some subtle changes to 500 mb pattern in
the extended forecast. Nothing that will change the overall +pna
pattern...but enough that will bring a storm track to our west and
push some warmer air into the region early to middle next week.
500mb zonal flow will be in place Sat night into sun before a weak
wave approaches Sun night...and then digs to our NE on Monday. Sat
night will be clear and cold with lows single below zero to the
north...and single digits above zero elsewhere. Sunday will start
off with sun...but clouds begin to move in during the afternoon as
the system approaches. Looks like any snow will hold off until sun
evening. Not expecting too much in the way of quantitative precipitation forecast...quarter of an
inch or less generally...as the surface low does not intensify until
it reaches the Maritimes on Monday morning. So a couple of inches
of snow possible Sunday...with clearing on Monday in west-northwest flow.
The downslope should allow things to warm again into the upper 20s
to middle 30s...which is close to normal.
High pressure then builds in late Monday into Tuesday as a decent
ridge builds aloft. Although middle-high clouds spilling in on Tuesday
will keep temperatures a little cooler than Monday. Another 500 trough
approaches by Tuesday night...although the most energetic part of it
stays northwest of New England. The models are in agreement that main surface
low stays to the west as well...but differ somewhat on timing...and
whether there is the development of another low on the coast. Any
precipitation will probability start as snow but with track to the west...will
get some warm in aloft at least...and could see some freezing rain or rain in
the mix. At this point...this does not look like a major
system...but still beyond day 5...and this winter the models can
change a lot in that timeframe.
Aviation /14z Friday through Tuesday/...
short term...VFR today through Saturday.
Long term...VFR Sat night and sun...then a period of IFR in snow Sun
night...improving to VFR again on Monday and Tuesday.
short term...have dropped the freezing spray advisory...with temperatures
warming...and winds/seas diminishing. Very cold temperatures late tonight
may require at least a couple marine zones needing another
freezing spray advisory at some point.
Long term...Small Craft Advisory likely on Monday in northwest flow and possible fz spray