Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 182139
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
539 PM EDT Fri Aug 18 2017

.SYNOPSIS...
A warm front will gradually push east of the region tonight. A
slow moving cold front will cross the region Saturday. High
pressure will build in from the west Sunday through Monday and
will slide offshore on Tuesday. A cold front will move in from
the west Tuesday night and will cross the region on Wednesday.
High pressure will build in behind the front Wednesday night
through Friday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Update...
Have updated the grids based on current conditions and latest
set of mesoscale models. Bands of heavy rain moved through many
areas this afternoon. There has been a lull early this evening,
however another batch of locally heavy rainfall will continue to
spread eastward from southern New Hampshire this evening.
Earlier, a report of an inch per hour occured with this
precipitation. Another inch of rain in a few communities will
bring storm totals locally into the 2 to 3 inch range. Highest
totals so far today have been in coastal York County. Radar
estimates are underdone for this area.

An areal flood advisory will remain in effect through 7 pm for
much of southern New Hampshire and far southwest Maine where the
heavier echoes continue. The greatest threat will be for urban
type flooding on roadways, culverts and low lying areas.

Much of the precipitation will begin to taper off late this
evening and become more scattered as best dynamics shift to the
east.

Made some minor modifications to the dew point, wind and sky
cover grids for this evening. The rest of the forecast will
remain relatively unchanged.

Prev Disc...
Warm front to the southwest continues to produce
rain and rain showers mainly across southern zones. Rain will be
occasionally heavy through the early evening hours as low level
jet combines with PWAT`s of 2 inches or better sweeping through
southern and coastal zones. Expect storm totals of 1 to 1.5
inches in southern New Hampshire and Coastal locations with
locally 2 inch amounts in midcoast Maine. Rain will begin to
taper off in these areas by mid evening and should clear most of
the forecast area by midnight. Ocean stratus and areas of fog
will blanket the region during the overnight. Lows will range
from the mid 50s north to the mid 60s south.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Warm front will be quickly followed by a slow moving cold front
on Saturday. As boundary layer winds turn into the west ocean
stratus will gradually get shunted eastward during the morning
hours although mid coast Maine may take much of the afternoon to
break out. Marginal instability associated with the front will
likely kick off afternoon showers and thunderstorms mainly
across New Hampshire and western Maine where heating will be
the greatest. Will be a fair amount of shear so some stronger
cells may produce some wind damage but CAPES may be a limiting
factor. Highs Saturday will range from the 70s in central Maine
to the 80s in western Maine and New Hampshire.

High pressure will build in behind the front Saturday night
bringing clearing skies downwind of the mountains. In the north
upslope flow and lingering moisture will result in mostly cloudy
skies and possibly a stray shower. Lows will range from the
upper 50s north to the mid 60s south.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Skies will become partly cloudy during the day Sunday as drier
air moves into the region behind the front. There could be a
lingering shower in the mountains early...otherwise, temps will
warm to the mid 70s north to the mid 80s south as a ridge of high
pressure builds into the area.

The ridge will move offshore Monday and Tuesday as a cold front
slowly approaches from the west. This will lead to increasing
temperatures and humidity for Monday and Tuesday. High temps
Tuesday will mainly range from near 80 in the mountains to near
90 in southeastern New Hampshire and extreme southwestern
Maine. Along with the warmer temps and higher humidity, the
threat of showers and possible thunderstorms will be on the
increase Tuesday afternoon through Wednesday as a cold front
approaches and crosses the region. Showers could linger
Wednesday night.

Cooler and drier air following the front for Thursday and
Friday as surface high pressure builds into the region. With the
colder air moving in aloft and an upper level trough developing
over the area Thursday and Friday, an afternoon shower can`t be
ruled out, especially in mountain areas, but most areas should
be dry.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
Short Term...IFR/LIFR ceilings and vsby overnight. Gradually
improving to VFR Saturday. VFR Saturday night with areas of
IFR/LIFR in valley fog.

Long Term...Mainly VFR conditions for Sunday into Tuesday with
IFR conditions possible in valley fog early in the mornings.
MVFR to IFR conditions likely Tuesday night and Wednesday in
showers and possible thunderstorms.

&&

.MARINE...
Short Term...Continuing SCA`s for tonight through Saturday.

Long Term...Winds should be diminishing and seas subsiding
Sunday and Monday and will be below SCA criteria through
Tuesday. Winds and seas will be increasing late Tuesday with
SCA conditions possible Tuesday night and Wednesday.

&&

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

&&

$$
NEAR/SHORT TERM...Cannon


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