Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 201358
Area Forecast Discussion
National Weather Service Gray ME
958 AM EDT FRI MAY 20 2016
An area of high pressure will build in today before sliding
offshore tonight. The high will bring sunshine and warmer
temperatures to the area both today and Saturday. A cold front
will drop south out of Canada and into northern New England
Saturday night while low pressure moves northeastward off the New
England coastline on Sunday. This system will likely bring some
rain to the area later Saturday night and Sunday. Low pressure
looks to linger around the region early next week with unsettled
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --950 am update: Currently sunny skies across the region and should
continue the rest of the day as a surface and upper ridge of high
pressure crests over the area. Temperatures will be mild reaching
into the 70s. Coastal areas can expect the afternoon seabreeze
keeping temps a little cooler.
636 AM...Minor ESTF update to
ingest the current mesonet into near term grids.
at 06z...GOES imagery showed some lingering mid and high clouds
over northern and eastern sections of the forecast area associated
with the upper trough. For today...a few morning clouds over maine
before the upper trough slides northeast otherwise a mostly sunny
day as surface high pressure center builds to our south. High`s
should be mainly in the 70s. The light synoptic flow should turn
onshore along the coast by afternoon...with readings falling back
into the 60s by late afternoon along the coast.
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.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Mainly clear and cool tonight as the ridge crests across the
forecast area with some late night valley fog and stratus. Lows should
bottom out mostly in the mid 40s to lower 50s with some cooler
readings in the mountain valleys. The ridge retreats offshore on
Saturday with sunshine giving way to increasing clouds during the
afternoon. High`s tomorrow should be within a degree or two of
today`s across the forecast area. An approaching upper trough
could introduce a few showers to western New Hampshire as well as
the international border area towards evening.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
The main forecast challenge revolves around how far north a track
low pressure to our south will take later Saturday night and
Sunday. While Sunday doesn`t look like a great day no matter how
one slices it with mean troughing in place, a nor`easter with a
cold rain could potentially make Sunday a washout. The overall
trend in the 00z guidance early this Friday morning has been for a
more northerly track in the SFC low which puts at least southern
and coastal zones in line for higher PoPs.
Latest ensemble guidance continues to show substantial spread in
the low track and resultant northward progress in the steady
precipitation shield. Solutions vary from a widespread rain event
for much of the CWA to more of a grazer for southeast zones. Based
on the latest ensemble means along with latest trends in the 00z
deterministic guidance, we have raised pops to low end likely for
most areas. Did not want to go too crazy as spread still remains
- with one of the possible scenarios still being out to sea or
close to it.
Western zones may not get into the action at least
with the steadier precip shield associated with the
frontogenetical forcing provided by developing mid level low
pressure. However, with the upper trough digging in there should
still be a good chance of showers. The best place to be on Sunday
could very well be central ME and the foothills as that area may
be spared the rain shield associated with the developing low and
the showers associated with approaching upper troughing.
In a nutshell, Sunday doesn`t look that great, but forecast
confidence isn`t overly high right now due to uncertainties with
the track of low pressure.
Thereafter, it looks like our upper low will want to take up
residence near or just south of New England Monday through
Wednesday so unsettled weather may continue. Monday may be the
better day as forcing for ascent may temporarily be shifted to
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Short Term /through Saturday/...lcl ifr in early morning valley
stratus and fog today and Saturday morning...otw vfr expected.
Long Term...MVFR to locally IFR conditions will be possible later
Saturday night and Sunday in low clouds and rain associated with
low pressure moving to the southeast of Cape Cod. How low
conditions go will be determined by storm track and that is
uncertain at this time. Lower conditions may continue through
early next week with stubborn low pressure sticking around. The
best day may be Monday when a long period of VFR conditions is
Short Term /through Saturday/...Winds and seas should remain
below Small Craft threshold as high pressure builds by to the
south of the waters.
Long Term...Low pressure moves to the south of the waters Saturday
night and Sunday. Small craft conditions look likely Sunday into
Monday as a result. A period of marginal gales will be possible
during that time depending on how strong low pressure gets and how
far north it tracks.
High pressure builds across the area with dry weather, much
warmer temperatures, and light winds today into Saturday. Minimum
relative humidity values both days between 30 and 40 percent
followed by good relative humidity at night. A coastal low may
affect the area with wet weather later in the weekend and early