Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 190319
Area Forecast Discussion
National Weather Service Gray ME
1119 PM EDT Tue Oct 18 2016
A warm front will lift northeast across the area tonight while a
cold front sweeps in from the northwest. A few showers will be
possible as this moves through. Expect warm weather on Wednesday
as an offshore wind brings dry air and a clearing sky, especially
to the south and east of the mountains. High pressure slides
across northern New England Wednesday night and into the Canadian
Maritimes on Thursday. Meanwhile, low pressure developing over the
Ohio Valley will track northeast toward northern New England by
Friday. This will bring a period of wet weather from late Thursday
through Friday night when a cold front pushes through from the
west. This front will bring colder weather for the weekend into
early next week.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --1115 PM Update...Have cancelled a portion of the dense fog
advisory close to the MA border as the warm front continues to
progress northward. The rest remains in effect until 1 am.
9 PM Update...Have issued a dense fog advisory for southeastern NH
and York County ME until 1 am. Visibilities have dropped to a 1/4
mile or less in this area. While the warm front is on the doorstep
just to the south, the cool moist low level marine layer is going
to be tough to dislodge through midnight. Otherwise, no
significant changes to the forecast.
615 PM Update...Have updated the forecast mainly to account for
latest trends in observational data. Cold air damming continues
across much of the region except for W/SW fringes of the CWA. The
SFC warm front will be slow to move now that it is nighttime and
have therefore adjusted temperatures for the next few hours based
on this philosophy. Otherwise, areas of drizzle and fog will
continue on the coastal plain this evening and into the overnight
Cold air damming continues to hang on across a large part of the
area south of the mountains, with clouds, fog and some drizzle for
the rest of the afternoon. The warmer and drier air is making some
inroads in parts of srn NH and the CT vly, and will see some
clearing and a brief warm up[ before sunset in these areas. The
Merrimack valley is the biggest question as if it does break out
before sunset temps could pop up close to 70.
Areas that do break into the surface warm sector will see temps
fall off a little bit this evening, but anyplace thats stuck in
the inversion will likely see the overnight min occur at sunset as
temps will begin to slowly rise overnight as the warm sector moves
in and southerly winds pick up a bit. This should eventually clear
out the fog and the low clouds in a lot of spots overnight. Cold
front could produce some SHRA in the north as well, but unlikely
to the south. Front should move into the north toward daybreak
and cross the coast shortly after sunrise.
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.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
West winds combined with warm air loft will allow the downslope to
warm the area quite nicely for Oct 19, with highs in the 70s
outside the mountains, and in the mid to upper 60s there. Could
see a run at 80 in the Merrimack valley. Any morning clouds in the
mountains will dissipate by midday with mainly sunny skies
Should be enough flow persisting into the night to prevent full
rad cooling, so lows will still be above normal, in the upper 30s
N to mid to upper 40s in the south, but definitely cooler than
previous nights. Look for mid to high clouds to begin to roll in
from the west after midnight.
.LONG TERM /THURSDAY THROUGH TUESDAY/...
High pressure moving into the Canadian Maritimes and low pressure
developing over the Ohio Valley will begin an onshore easterly
flow over much of New England on Thursday while high level cloud
cover moves in from the southwest in advance of an approaching
upper level trough. Models are in better agreement than they were
at this time yesterday on the way this trough and its relevant
surface features will evolve, with the surface low tracking
through northern New England before merging forces with a weak
tropical low racing northward off the East coast. The resulting
low will then pull northward into the Gulf of Saint Lawrence while
a sharp upper level trough lingers in its wake over New England
through the weekend and into next week.
On Thursday, expect cooler conditions with increasing clouds and
an onshore wind developing. This should keep temperatures in the
50s for most of the area, with rain showers beginning in the
afternoon especially in the north and west. A warm front tries to
lift north across the area Thursday night into Friday, though the
flow will still be onshore for most of the region, holding
temperatures in the 60s with abundant cloud cover. By this time,
the onshore flow could even lead to areas of drizzle developing
near the coast while the more persistent rain lifts north into
On Friday, low pressure moving into northern New England from the
west joins forces with low pressure moving north off the East
coast, spreading rain through the region. With the tropical
connection here, it is possible that some of the rain could be
heavy though flooding is unlikely. Low pressure moves into
northeast Maine by Saturday morning, with the more persistent rain
moving east with it and a cold front sweeping in beneath it.
Should see colder temperatures beginning on Saturday as cold air
gets drawn in behind the system. Could see some lingering showers
mainly in the mountains, which may eventually transition to snow
showers as the cold continues to pour in Saturday evening.
Upper level trough is slow to depart, keeping New England in a
cold northwesterly flow. This will keep daytime highs in the 40s
and low 50s. Nighttime lows will be in the 20s and 30s, though
persistent northwest winds may prevent ideal radiational cooling
conditions until the surface high arrives midweek.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Expecting improvement at terminals, to at least MVFR
later tonight as southerly winds begin to pick up and break the
inversion. Until then we expect dense fog. Could see the valley
locations go down briefly to IFR toward daybreak. All terminals
will see VFR shortly after sunrise on Wed, which will persist
through Wed night.
Long Term...Expect increasing clouds Thursday, primarily from the
top down. Conditions may become MVFR to IFR Thursday night as
onshore flow persists in bringing in low level moisture. More
substantial rainfall is possible on Friday and Friday night as low
pressure moves through the area, likely keeping conditions IFR or
worse for most of the time. A cold front pushes east through the
area Friday night into Saturday morning, helping to clear out some
of the clouds and potentially bring VFR conditions again south of
the mountains. North of the mountains, lower clouds and rain/snow
showers may persist through the weekend.
Short Term...Expecting a surge SW winds ahead of a cold front this
evening, and SCA will remain up for gusts of 25-30 kts, which will
diminish towards daybreak. No SCA conditions expected Wed and Wed
Long Term...East to southeasterly flow ahead of low pressure
moving through northern New England should stay near or below
advisory levels, but the onshore nature of the wind will allow
wave heights to build to over 5 FT. A cold front pushes east
across the waters early Saturday morning, with a west to
northwesterly flow behind it which will likely gust above 25 KT at
-- Changed Discussion --ME...Dense Fog Advisory until 1 AM EDT Wednesday for MEZ018-023.
NH...Dense Fog Advisory until 1 AM EDT Wednesday for NHZ008-010.
MARINE...Small Craft Advisory until 8 AM EDT Wednesday for ANZ150>152-
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