Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 272258

Area Forecast Discussion
National Weather Service Gray ME
658 PM EDT Sat May 27 2017

Weak high pressure will remain over the area through Sunday and
will shift offshore Sunday night, allowing us a window of dry
weather. The next system over the eastern Great Lakes will lift
north into Quebec Sunday night and will drag a trough toward
the region on Monday into Tuesday with unsettled weather. Warmer
weather returns by the mid to latter part of the week but with
the chance of showers each day.


7 PM Update...Have adjusted the forecast a bit based on latest
observational data, mainly sky cover and temperatures for the
next few hours. Mostly sunny conditions should lead to early
evening mostly clear skies across much of the area except for
southern NH where the clouds will hang on. Eventually these
clouds should spread northeastward. Otherwise, dry weather is
expected to continue this evening.


Weak high pres builds over the area tonight with partly cloudy
skies. Winds will be light and some residual low level moisture
will remain so patchy fog is possible later tonight in some
areas. Temps will cool into the mid 40s to near 50.


High pres crests over the area Sunday into Sunday night. Any
early morning patchy fog will quickly burn off by mid morning.
Skies will be partly sunny and due to the air mass being
modified, the temps will be milder Sunday reaching into the 70s
except along the coast where seabreezes will keep temps cooler
into the 60s and coolest along the mid coast where temps will
struggle to get out of the 50s. Sunday night will remain dry as
the high begins to slip off the coast. Lows should be in the
upper 40s to lower 50s.


At 500 mb, models continue to have run to run timing differences
regarding configuration of omega block covering the ern half of
NOAM and the N Atlantic, but the overall pattern will feature a
closed near the southern tip of Greenland and another closed
low just N of the Great Lakes. For the most part, especially
early to mid week we should sit in the SW flow aloft ahead of
the 500 mb low to our WNW, which will mean temps running near
normal, and sunny breaks at times, despite a chc of showers.

Initially, though with sfc low approaching from the west on
Monday, will see onshore flow develop, so look for cloudy skies,
cool temps and showers on Monday. Highs will only be in the
low-mid 50s at the shore, and may reach around inland 60 at some
inland locations, most likely in the downslope in the CT vly,
although some DZ and F are possible Mon afternoon and Monday
night as well. This system move through Monday night, with a bit
of a break late Mon night into Tue morning. Another wave rotates
around the low later Tue into Tue night, and another round of
showers can be expected. Flow is weaker on Tue, and onshore flow
will keep the coastal areas cool, but enough SW flow aloft
should allow a little mixing in interior central and srn NH,
where temps will be the highest generally in the upper 60s to
around 70. Look for lows in the low 60s in wrn/central ME, and
more around the upper 50s along the immediate coast.

After that, it looks like 2 more waves are possible between Wed
and Saturday, so showers will be possible a couple of days in
this time frame, but also sunny periods can be expected as well.
The W-SW flow should keep the marine lyr mostly off shore,
although it will likely be cool at the beaches. Highs around 70
inland, and closer to 60 at the beach.


Short Term...VFR conditions. Due to some remaining residual low
level moisture keeping dewpoints in the mid-upper 40s, some
patchy fog expected possible allowing conditions to become
variable to IFR til morning. Any fog will quickly burn off by
13z so all areas will be VFR Sunday into Sunday night.

Long Term...Any morning VFR will drop to MVFR by afternoon, and
probably IFR by late in the day in the day Monday continuing
thru Mon night. Some improvement on Tue, although will
probably be variable MVFR to IFR, with VFR and tempo MVFR in
SHRA Wed and Thu.


Short Term...Winds and seas to remain minimal tonight through
Sunday night.

Long Term...Winds could get near SCA briefly on Monday, but for
now, look to stay below. Otherwise, winds/seas stay below SCA
Mon night through Thu.


The astronomical high tide in Portland is 11.9 feet MLLW at
115 AM Sunday. Winds will remain light and seas low. The high
water conditions have required a coastal flood statement to
indicate some areas may exceed their minimal benchmark levels
for isolated minor flooding.





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