Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 231540
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1140 AM EDT Wed Aug 23 2017

.SYNOPSIS...
A cold front will slide well offshore today. High pressure and
drier air follows the front late today through the weekend.
High pressure will then continue to dominate through the
midweek period as low pressure develops over the mid Atlantic
region.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...

1140 AM...A few isolated showers have developed over mid coast
Maine in vicinity of the baroclinic zone that remains just
offshore. They should quickly sweep offshore over the next 1 to
2 hours. For this ESTF update...I adjusted near term grids to
reflect current radar and satellite trends as well as the latest
mesonet. The small craft was dropped and replaced with an SCA
for hazardous seas for the outer waters.

Prev disc...
900 AM...At 12z the surface cold front extended from the rooftop
of Maine southward into Penobscot Bay. Dewpoints remain in the
60s to near 70 immediately behind the front. The mountains and
Connecticut valley have dewpoints in the 50s...and that drier
and less humid air will advect eastward all the way to the coast
by afternoon on a strengthening post frontal westerly flow. For
this ESTF...near terms grids were adjusted to reflect current
satellite trends as well as the latest mesonet.

Prev Disc...
650 AM Update...
Just a few lingering showers now racing ENE through the
mountains this morning behind the main activity. Low stratus is
moving offshore rapidly with a few pockets of low stratus and
fog that have formed recently in the breaks in the cloud decks.
This should mix out as warming ensues this morning and as
westerly winds increase.

Made a few changes to PoPs and weather grids for this update.


Previous discussion...
Large convective system which brought damaging winds to the
region last night as well as widely varying amounts of
precipitations (less than two tenths in Laconia to over an inch
at Jaffrey) is still moving east and south this morning. Cold
front has slowed along the coast and will bring additional QPF
there and just inland for the next few hours before the next
short wave kicker moves it offshore.

Sprawling closed upper low will keep spinning over eastern
Canada today pushing lobes of vorticity through the northeastern
states. Drier air will filter in on gusty WNW winds today
bringing sunny skies downwind of the mountains and foothills
where clouds may hang on a little longer. A rogue sprinkle may
occur over the highest peaks through this morning. Highs will be
warmest along the coast and inland where we should see lower to
mid 80s. Over the north 70s will be more common.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Drier and cooler air will filter in tonight as high pressure
pushes in from the west. Westerly winds will lighten and dew
points will tumble into the 40s and 50s. This will allow for
temperatures to follow suit, with mid to upper 40s across the
north to lower to mid 50s south. Patchy fog will develop in
valleys and low lying spots.

High pressure builds in farther on Thursday. Light northerly
winds will continue to keep things dry and bring some cooler air
down from Canada. Still, highs will be seasonable and in the
upper 60s to upper 70s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Models in fairly good agreement in keeping upper trough
meandering over the northeast for the end of the week and for
much of the weekend as a surface high gradually builds in from
the west. Cold pool aloft settling into the northeast will
result in partly cloudy and cool nights with a mix of sun and
clouds during the day Thursday night through Sunday. Nightly
lows will range from the mid 40s north to the mid 50s south.
Highs will top out from the mid 60s to the mid 70s south.

Upper trough will gradually break down and fill Monday through
Tuesday as high pressure remains in control over the northeast.
Will see a slight warming trend with much of the forecast area
reaching the lower to mid 70s by Tuesday.

Shortwave approaching from the west will bring the next chance
of precip into the northeast by midweek but models diverge quite
a bit at this point so have generally followed SB solution
bringing low chance pops into southern zones by Wednesday.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
Short term /through Wednesday Night/...Plenty of low level
moisture still kicking around this morning with conditions
ranging from IFR to VFR. As drier air works in from the NW today
fog and stratus will push offshore or mix out. Gusty westerly
winds of around 12G20KTS are expected along with VFR ceilings
which will give way to SKC eventually. Valley fog along with
marine fog will return tonight as dew point depressions drop.

Long Term...VFR conditions are expected to prevail Thursday
through the weekend other than some early morning valley fog.

&&

.MARINE...
Short Term /through Wednesday Night/...Seas remain in the 4-7 ft
range and winds are just barely above small craft criteria this
morning. Winds will decrease sooner than seas which may remain
up through around noon. The outer waters of Penobscot Bay may
need to be replaced by a Small Craft for Hazardous Seas for a
few more hours at that time.

Long Term...Small craft conditions are not expected Thursday
through the weekend.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 8 PM EDT this
     evening for ANZ150-152-154.

&&

$$

ES



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