Area Forecast Discussion
Issued by NWS Portland, ME
FXUS61 KGYX 270128
Area Forecast Discussion
National Weather Service Gray ME
928 PM EDT Mon Sep 26 2016
High pressure moves east tonight with a cold front arriving from
the west. Along the front expect a period of showers arriving from
west to east tonight into Tuesday morning. Conditions should dry
out behind the front on Tuesday with temperatures a few degrees
warmer. Low pressure developing along the offshore front will
develop a northeasterly wind over Maine and New Hampshire Tuesday
night, bringing clouds back in to the area. Several waves of low
pressure will track northeast along the front through the western
Atlantic, with an occasional chance of showers especially near the
coast. The best chance of rain will be this weekend when the large
upper level low pressure system over the Great Lakes lifts to the
north, spreading rain into New England.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
930 PM Update...Have updated the timing of PoPs overnight a little
bit (mainly a little slower due to the dry column in place as seen
on our 00z sounding). Otherwise, no significant changes.
610 PM Update...Little change to the going forecast. Just a few
minor adjustments to PoP and sky cover for the next few hours
based on latest observational and mesoscale model data. The
evening hours will feature increasing clouds but remain dry.
Expect increasing clouds through the evening and a moistening
southerly flow ahead of an approaching cold front. This front is
currently over western Pennsylvania and New York pushing eastward.
Areas of showers have been fairly widespread along the front in
this area, and expect this trend to continue as the front moves
eastward into New England tonight. There could be multiple
different clusters of showers, with one moving to the north near
the Canadian border and another moving in from southern New
England, but expect the overall coverage of rain to be pretty high
tonight even as total rainfall amounts remain less than half an
inch. Best chance of rain generally occurs in a 2 to 4 hour window
beginning in New Hampshire just after midnight and pushing through
western Maine around sunrise.
Temperatures tonight will not be nearly as cold as last night due
to cloud cover and increasing low level moisture. In fact,
temperatures will not follow their normal diurnal trend, with the
lowest temperature occurring early in the evening for much of New
Hampshire before temperatures rise as the front approaches.
Attempted to place this trend into the hourly temperature
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Cold front will still be making its way east through western Maine
Tuesday morning, so showers will be ongoing there Tuesday morning.
Should see clearing by around noon, with temperatures behind the
front warming into the 60s or even low 70s. As the front moves
offshore, low pressure strengthens along it, causing northeasterly
winds to develop. This will send cool, moist air southwestward
through Maine and into New Hampshire overnight. For the most part
this will consist of cloud cover, but cannot rule out some drizzle
as well. Models tend to overdo the QPF in such scenarios, but some
light accumulation of drizzle is possible. Temperatures again stay
warm due to cloud cover and moisture over the area with lows in
the upper 40s to low 50s.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Unsettled weather likely in the long term as models showing a
stalled front to our east and a large cutoff low to our west
through the period. This will result in an extended period of
northeast winds that will keep the region cool and cloudy with
sacttered showers. A couple of periods of steady rain are
possible as the 500 ridge moves past us later in the week and then
again late in the weekend or early next week when the upper low
moves over us. The big question is how much rain will this system
produce. It looks like the heaviest rain will remain to the south
and west of the forecast area, closer to the closed upper low.
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Short Term...Conditions deteriorate tonight around midnight in
western New Hampshire as showers arrive from the west. This should
spread eastward into western Maine in the early morning hours.
Conditions could go IFR especially in heavier showers and along
the coast where lower ceilings are likely. Front pushes to the
east in the morning on Tuesday, helping bring VFR conditions back
to the region from west to east. Could see some MVFR ceilings hang
on north of the White Mountains through the afternoon. Tuesday
night a northeast flow develops and sends a layer of low clouds
and possible drizzle back to the west across Maine and into
eastern New Hampshire. This could bring IFR conditions after 00Z
Wednesday, with the western New Hampshire terminals HIE and LEB
least likely to be impacted.
Long Term...Expect VFR for most of Wednesday then mvfr moves in
Wednesday night through much of the remainder of the period with
some IFR likely in any fog/stratus that settles over the region
Short Term...Although southerly flow does increase this evening
and tonight, it should remain below advisory levels and will not
persist long enough to cause wave heights to build too high. At
this point advisory conditions are not expected, though gusts to
20KT and wave heights occasionally up to 5 FT in spots are
possible. Front crosses the western Gulf of Maine Tuesday morning
bringing light winds along and behind it.
Long Term...Expect winds and seas to build to small craft criteria
due to the persistant and strengthening northeast wind.
NEAR TERM UPDATE...Ekster