Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 190304 AAC
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1104 PM EDT THU AUG 18 2016
High pressure will build in from the west tonight and crest over
the region Friday. High pressure will shift offshore Friday night
and will hold off the coast through Saturday night. A cold front
will approach from the west late Sunday and will slowly cross the
region Sunday night and Monday. High pressure will build in from
the west Monday night through Wednesday.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Showers have ended and temperatures are dropping quickly. Dew
points are also creeping down. Water vapor imagery shows dry air
continuing to push into the region. Only minor changes to the
forecast for this update.
6 pm Update...
Only minor changes to the forecast which is in good shape. CUmulus
clouds are decreasing quickly this evening in a drier airmass.
Have lowered cloud cover in most areas. An isolated shower is
still possible over southern NH and offshore along the southward
moving cool front for another hour or so. Calm winds and building
high pressure tonight will allow for good radiational cooling and
dropped temperatures slightly across the north in line with latest
HRRR and other short term models.
High pressure builds into the region tonight allowing skies to
becoming clear by early evening. Winds will become calm as the
high settles over the region. With clear skies and calm winds
areas of valley fog can be expected to develop toward and after
midnight. Temperatures will be comfortable ranging from the mid
50s in the mountains to lower 60s elsewhere.
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.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
High pressure will continue to be centered over the area through
Friday night. This will mean Friday will have a sunny day and clear
night with near calm winds. Friday will be another warm day with
temps reaching the upper 70s in the mountains to mid 80s
elsewhere. Dewpoints will remain comfortable in the lower 60s.
Friday afternoon seabreezes can be expected along the coast
knocking down temperatures along the coastal areas. Stayed close
to a blend of model guidance for temperatures.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
High impact weather potential: Low, some localized heavy rain
possible Sunday night into Monday.
A slightly more amplified 500 mb pattern is in the forecast as
the strong western Atlantic ridge breaks down somewhat, and this
will allow fairly decent troughing to build equatorward and cross
the region early next week. This will be followed by good ridging
over the area through the end of next week.
Saturday will actually be a fine and warm August day as surface
ridge slowly shifts offshore. Look for mainly sunny skies, Tds
in the mid 50s to around 60, so not too humid, and maxes will in
the 80-85 range, with slightly warmer temps in the upper 80s in
interior southern NH. As the high shifts offshore Sat night and
Sunday, humidity increases, as will clouds and the threat of
showers. Still overall, Sunday looks good, with partly sunny skies
and highs generally back into that 80-85 range, although it will
be noticeably humid with TDs rising into the mid and upper 60s.
There will be the chance for a scattered showers or thunderstorm,
mainly over NH in the afternoon.
As the 500 mb trough approaches from the west on Sunday night it
starts to dig and begins to negatively tilt, which will slow
progress of associated surface front as it crosses the CWA. This
looks to be a farily dynamic wave, but given the time of year,
hard to say how much convective scaling problems may play a roll
in its development, but it looks like a fairly solid chunk of
energy from when it crosses the gulf of AK. If this is the case,
with good moisture inflow ahead of it, should see the potential
for locally heavy rainfall again, and perhaps slow moving bands,
Sunday night into Monday morning. The front crosses the CWA
Monday, and some relatively cooler and drier air will move into
the area mid-week, although temps will only drop to around normal,
Once the ridging builds back in by the end of the week, it will
begin to warm up again.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term...VFR through Friday night except for some IFR/LIFR
conditions in areas of valley fog 05z-14z.
Long Term...Possible extended flight restrictions Sunday night
into Monday morning with heavy rain. Otherwise look for mainly
Short Term...No flags.
Long Term...Expect sub-SCA conds on the waters Saturday through