Area Forecast Discussion
Issued by NWS Portland, ME
FXUS61 KGYX 281038
Area Forecast Discussion
National Weather Service Gray ME
638 AM EDT Wed Sep 28 2016
Canadian high pressure will continue to build into the region
from the north today through Thursday. The high will remain parked
to our north while low pressure over the midwest drifts slowly
north and east. Moisture from this system may spread into southern
areas Friday. The best chance of rain will be this weekend when a
large upper level low pressure system over the Great Lakes lifts
to the north, and may spread rain into New England.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
630 am update: Cloudy conditions across all southern and central
areas due to the northeast flow of maritime air. Some drier air
mixing into low levels preventing any drizzle or fog from forming.
Skies across the mountains remain mostly clear. Made minor tweaks
to temps for next few hours otherwise no changes needed at this
Previous Discussion: A rather strong Canadian ridge of high
pressure will continue to build south into the region today. It
now appears drier air will filter into the northeast flow today so
not expecting any drizzle or fog to develop as earlier thought.
Some early morning valley fog still possible though but unrelated
to the maritime northeast flow. Temps will be a little below
seasonal with highs around 60 based on a blend of models.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Tonight and Thursday more of the same with the large blocking Canadian
ridge of high pressure anchored to the north and in control
pumping a dry and persistently cool northeast flow. All models
agree on keeping it dry through Thursday as the shield of
precipitation will remain well south. Temps to remain cool.
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Chance of high impact weather: Minimal.
Dominant feature affect our weather at 500 mb b over the long
range period will be closed low meandering around the Midwestern
CONUS, and associated downstream ridging over New England.
Actually, 00Z GS and Euro are in somewhat better agreement than
previous models runs as to timing, although Euro is a about 12-24
hours slower in lifting the low northward and then getting caught
up in tough extending from low south of Greenland. DEspite the
better agreement, this is not a high confidence forecast, as the
closed low will be separated from the flow and surrounded by
ridging, and troughing that models are suggesting starts to move
it along is not all that impressive.
Models are trending to keep things mostly dry through Friday at
this point, with some moisture working up in the weak SW flow
aloft/ We will be stuck in that areas through the weekend and
perhaps into Monday, and for this reason have chance pops in the
forecast for most of the CWA in this timeframe. It is unlikely
every period will see SHRA, but for now depending on what happens
with the closed low have to include a chance. Also, there will be
lots of clouds, given the moist S flow aloft and the low-mid lvls
E-NE flow. Still could see clearer periods as dry air will be able
to be pulled in from the NE at times, for this reason, have
undercut Superblend sky a little to call it mostly cloudy rather
than overcast. The other thing will be air aloft will be above
normal, around 10C, through at least Monday /or whenever the
cooler air in the closed low eventually moves through/, and temps
overall should end up around normal for highs and above normal for
overnight lows. Periods when the flow shifts onshore may be a few
degrees cooler, but the water temps not that far off climo normals
at this point. Overall highs will be in the 60s most days, and
overnight lows will range from the mid 40s to low 50s.
The middle to end of next week will all depend on how things
shake out prior to that time, but could see a dry period around
the middle of the week, with slightly cooler temps, but not
significantly below normal.
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Short Term/through Thursday/...Variable conditions today through
Thursday with VFR conditions over central and mountain areas with
mainly MVFR conditions over southernmost areas. Some overnight
and early morning valley fog til 13z will allow for lcl IFR
Long Term...Will have to watch for low clouds through the
extended period, and maybe a few SHRA. Best chc for flight
restrictions would be Fri night through Sunday, but this is a low
Short Term /through Thursday/...Strengthening Northeast flow will
bring SCA conditions outside the bays through Thursday.
Long Term...Expect persistent NE flow Friday through the weekend.
Winds will, for the most part, remain below SCA, but expect seas
to build to 5-7 feet, especially south of Casco Bay.
MARINE...Small Craft Advisory until 9 PM EDT Thursday for ANZ150-152-