Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 201404

Area Forecast Discussion
National Weather Service Gray ME
1004 AM EDT Tue Mar 20 2018

High pressure will continue to settle over northern New England
today bringing continued colder than normal temperatures. A
storm system will pass to our south late Wednesday and Thursday
likely bringing accumulating snow to much of the forecast area.
An upper level low will cross over New England this weekend. A
storm may form well out to sea early next week.


10 AM Update...Little change to the going forecast. Sunny skies
are expected today with perhaps an increase in clouds in the far
south late. Winds will be lighter than yesterday even though
temperatures will still be a bit chilly.

625 am Update: Clear skies and light winds early this morning.
Another very cold start to the morning with minor tweaks to the
early morning temps based on latest obs.

Previous Discussion:
Another sunny day today as high pres settles over the region.
Temps will continue to be below normal. The good news is the
winds will be much lighter to near calm conditions.


Low pres develops off of DELMARVA tonight and Wed and spreads
thickening clouds northward into southern areas later tonight
and further north Wed morning. Some light snow or mixed
rain/snow should begin to develop into southern areas by later
in the day. Boundary layer temps at the onset of any
precipitation will be marginal for all snow so a mix expected at
the onset, but by evening evaporational cooling and increased
UVV should wipe out any warm layers. Used a blend of models for
timing. Temps will once again be below normal.


A complex area of low pressure will move northeast off the New
England coastline Wednesday night into Thursday. Initial surface
low will track just east of the Gulf of Maine, before a
secondary system, coupled with the upper low follows a similar
track during this period.

Models continue to diverge somewhat with this system. As the
confidence levels increase that some accumulating snow will fall
over southern New Hampshire and southern Maine, the range of
possible scenarios still exists. At this time, will use a blend
of most available guidance within the 00Z suite, however will
lean slightly towards the middle of the road GFS in terms of
snowfall amounts. At this time, it appears that a stripe of 3 to
6 inch snow totals will be possible over southern areas. This
forecast lines up well with our neighbors as well as WPC.

Temperatures Wednesday night should be cool enough in the
boundary layer to have any mix with rain restricted to the over
the offshore islands.

A period of light snow is possible over eastern portions of our
forecast area on Thursday as the system lifts off to the
northeast. Some upslope snow showers possibly in the mountains
as well, especially the western mountains of Maine.

Plenty of clouds will remain in place for Friday as an upper
level low pressure system crosses over the Northeast. Scattered
snow showers are a possibility, especially over the higher

This weekend will feature yet another upper level low pressure
system to cross the region. More scattered snow showers are
possible, especially in the mountains. Below normal temperatures
will continue as well.

Finally, the European model and previous runs for other models
continue to suggest the formation of a storm well out to sea
early to mid week next week. This storm will be too far out to
sea to affect the region with changing sensible weather
conditions. However, this has the potential to bring large, long
period swells to the coast and has been noted in the coastal
flood discussion below.


Short Term /through Wednesday/...VFR conditions today into early Wed.
By late Wed some MVFR conditions may develop over southern
areas in developing areas of light rain or snow.

Long Term...Ceilings and visibilities will lower Wednesday into
Wednesday night and early Thursday over southern New Hampshire
and southern Maine. Initially, there may be a snow, rain mix
before the precipitation changes to all snow. Mainly VFR or MVFR
over northern areas.

Occasionally MVFR conditions are possible in any scattered snow
showers Friday into Saturday.


Short Term /through Wednesday/...Winds and seas to remain light
into tonight.  Small craft conditions will likely develop late
tonight and likely increase to Gales Wed as the intensifying
storm system develops off the mid Atlantic coast.

Long Term...Gale force winds will continue into Thursday as
winds continue to back with time. Winds and waves will then
slowly diminish with time Friday and into the weekend. An
intensifying offshore storm may produce large swells next week.


The highest tides of the month will combine with an increasing
storm surge and building waves Wednesday night to allow for
beach erosion, splash-over and possibly minor coastal flooding.
Total water level tables have been adjusted for this tide due to
the increasing northeasterly winds.

Models are suggesting the possibility of a large and intense
storm to develop well out to sea next week. The forecast
suggests this storm may form a small loop and retrograde Monday
night into Tuesday. This may produce large, long period swells
next week which may lead to some beach erosion. Note, astronomical
tides are relatively low next week.


MARINE...Gale Watch from Wednesday morning through Thursday afternoon
     for ANZ150>154.



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