Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 201519
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1119 AM EDT Fri Oct 20 2017

.SYNOPSIS...
Slightly cooler weather is expected today in the wake of a cold
front but temperatures are still expected to be above normal.
Another warming trend with faIr weather is expected Saturday
through Monday. A cold front will approach on Tuesday bringing
the likelihood of some much needed rainfall during the midweek
period.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1100 AM update...
Quick update to tweak temp/td/rh grids. Temperatures once again
are well on thier way above normal. Expect mostly sunny skies
through the afternoon along with a moderate northwest flow. Have
also dropped SCA headlines which have expired. No other changes
planned for current forecast.

645AM UPDATE...
Have updated the forecast to tie hourly temperature and dewpoint
trends to latest observations.

ORIGINAL DISCUSSION...
Cold front is moving through the area at this hour with drier
and cooler air moving in behind it for today. With decent mixing
expect dewpoints to fall into the low 30s during the afternoon
while temperatures warm up into the upper 60s. This will bring
some low relative humidity values especially over southern
areas. Combined with recent dry weather and a light breeze, this
will lead to conditions favorable for wildfires.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
High pressure slides east and crests over New England tonight.
This should allow for some decent radiational cooling conditions
especially in the southwestern part of the forecast area and the
New Hampshire valleys. Temperatures could drop down toward the
freezing mark. But on Saturday warmer air will be spilling in
from the west and temperatures warm up into the upper 60s and
low 70s again.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A weak warm frontal boundary will be in the vicinity of the CWA
Saturday night and Sunday. However, the feature will be
associated with very little fanfare...just above normal
temperatures. Highs should be well into the 70s on Sunday,
especially across southern zones.

Deep layer ridging centered just to our east will aid in
providing another well above normal day Monday in the
temperature department. Highs should be into the 70s once again.

An amplifying trough will move into the Ohio Valley on Tuesday
which will aid in turning surface winds more south or
southeasterly across the region. This should allow for richer
low level moisture to move into the region which may allow for
low clouds and possibly some drizzle or light showers. By the
end of day, stronger forcing for ascent should arrive across
western zones allowing for a steadier rain or at least more
widespread showers to develop toward evening. Given the expected
deep layer meridional flow in place, it will take awhile for
the rain to move out of the region - in fact a second wave may
move into the area Thursday night and Friday. Overall, the area
needs rainfall. Some rivers are at record lows for this time of
year and the fire weather threat continues to increase. However,
GFS and ECMWF ensembles are in pretty good agreement with most
members showing a 1-3" rainfall across the region midweek into
the weekend.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Short Term...VFR conditions expected today and tonight. Winds
shift to the west northwest and may gust up to 20 KT. But these
gusts will diminish this evening.

Long Term...Widespread VFR conditions will continue under high
pressure. High will be more centered overhead over the
weekend...so valley fog and LIFR conditions will be possible at
HIE and LEB. Increasing low level moisture will occur Monday
night and Tuesday, and this may introduce lower conditions in
low stratus and possibly fog.

&&

.MARINE...
Short Term...Winds shift to the west northwest this morning
behind a cold front. Wind speeds continue to decrease but wave
heights continue to stay up for a few more hours this morning.

Long Term...SCA conditions are likely late Monday night through
Tuesday night as a cold front approaches from the west and
southerly winds increase out ahead of it.

&&

.FIRE WEATHER...
Relative humidities will drop into the mid 20s to mid 30s in
southeast New Hampshire and southwest Maine this afternoon along
with winds of 10 to 15 mph. This would come in just under
meteorological RFW conditions, and will elevate the threat of
wildfires.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$



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