Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 051547 AAA

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1047 AM EST Mon Dec 5 2016

A weak low pressure system will bring some light snow to the
region on today. High pressure will settle in for Tuesday. Low
pressure may affect the region with more light rain or snow
Thursday with colder air following for Friday and over the


Update...Have increased PoP on a line NE of about LEB to MHT. Snow
continues...banded at relatively warmer air aloft slams
into very cold air mass over Downeast and the Crown of Maine.
Brief burst of 1/2 to 1 inch per hour have been reported and
should continue for areas around PWM and NE for the next couple of
hours. With 12z kgyx sounding wet bulb temps near
-10C from the surface thru 600 mb...any lift is in or near the
snow growth zone. Snowfall ratios should be above climatological
norms. So I have also bumped snowfall amounts up an inch or
so...with max totals around 3 inches near the mtns...where Ely
inflow will enhance lift. Finally forecast soundings are pretty
devoid of a warm I have kept precip types snow or rain
based on surface wet bulb temps. Any mixed hydrometeors are most
likely heavily rimed flakes than sleet actually mixing in.

Prev Disc...
Radiational cooling dominated the first half of last night with
clear skies and light winds. Early this morning, clouds will
continue to thicken and lower. A north wind has developed along
the coast which will keep an inversion in place.

Currently forecasting cooler readings today than most model
guidance would suggest. A wet bulbing effect will keep our
atmosphere on the chilly side today as the snow attempts to fall
through a layer of very dry air in the lower portions of the

The chilly temperatures and low dew points will allow most of the
precipitation to fall in the form of snow with only a few of the
coastal islands may see a mix with rain at times. Although the
system moving through the region remains weak, sufficient inflow
from the Gulf of Maine and low level convergence will allow for
light snow to progress eastward today. Some of the precipitation
will remain as virga at the onset due to the initial conditions
described above. Nevertheless, an inch or two snowfall expected
most areas today. Onset time will be critical with possible very
slick conditions for the morning commute over southern New
Hampshire. A special weather statement has been issued for this


The light snow will be over in most areas by evening, with the
exception of the Rockland and Penobscot Bay area which may hold
onto some evening flurries as the weak surface trough and
associated short wave aloft exit to our east. Clearing skies will
lead to more chilly conditions with the new snow cover.

A surface ridge of high pressure will reestablish itself over New
England on Tuesday. Some high thin cloudiness may enter southern
areas late in the day as low pressure moves up and then off the
Mid Atlantic coast.


Several fast moving short waves will move through the region
through the outlook period. The first will be Tuesday night into
Wednesday with a period of light snow and the next will be on
Thursday with another bout of light snow or snow showers. Nothing
more than light accumulations are expected with these moisture
starved systems. Models are finally in general agreement of no
major development of any coastal storms with these short waves. By
Friday and into the weekend much colder Canadian air moves across
the region on a broad northwest flow aloft and at the surface.
Mountain orographic snow showers can be expected Friday into
Saturday with the cold northwest flow. The coldest air mass of the
season can be expected to arrive late Friday and into the weekend.


Short Term...Marginal conditions for LLWS however the wind speeds
aloft from the southwest are not overly strong. Some IFR and
possibly a brief period of LIFR conditions today. Conditions
improve to VFR for tonight and Tuesday.

Long Term...MVFR conditions expected Tuesday night into Wednesday and
again on Thursday.


Short Term...Winds and seas will remain below Small Craft Advisory
criteria for the most part in the short term. There will be a
period this evening with the trough exiting to the east with gusty
conditions. Westerly winds will be just below SCA criteria.

Long Term...Late in the week a strong west to northwest flow
combined with strong cold air advection will develop with winds
possibly approaching gale force Friday into Friday night.





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