FXUS66 KSEW 261039
Area Forecast Discussion
National Weather Service Seattle WA
339 AM PDT Mon Jun 26 2017
.SYNOPSIS...Onshore flow will bring much cooler weather and mainly
night and morning clouds for the upcoming work week. An upper
level trough will move through the area next weekend for a slight
chance of showers.
.SHORT TERM...Satellite imagery shows plenty of mid and high level
cloud cover over the area the morning. This cloud cover making it
tough to pick up the stratus on the fog product imagery. Surface
observations at 3 am/10z show the stratus has made it as far east as
Gig Harbor. Temperatures have dropped from the record highs on
Sunday down into the mid 50s to mid 60s.
Stratus will continue to move inland this morning covering most of
the area by 15z. In addition to the stratus plenty of mid and high
level moisture embedded in the southwesterly flow aloft moving
through the area as well. There have been a couple of lightning
strikes off the coast overnight. Even with marine layer
stabilizing the lower layers there is some weak instability aloft
this morning. There is also a weak vort max moving inland south of
the area. Langley Hill radar is showing precipitation echoes but
expect most of this is not hitting the ground. Will add a slight
chance of showers to the forecast this morning. Stratus will burn
back to the coast this afternoon with the mid and high level cloud
cover thinning out for mostly sunny skies for all but the coast.
Temperatures with the marine air in place will be as much as 25
degrees cooler with highs in the 60s along the Coast and mid 60s
to mid 70s inland.
Not much change in the pattern tonight through Wednesday morning
with low level onshore flow and weak trofiness aloft. End result
of this pattern will be late night and morning cloud cover over
the interior with the stratus burning back to the Coast in the
afternoon. An upper level ridge offshore will beginning moving
toward Western Washington Wednesday afternoon. Highs will be near
normal with lower to mid 60s on the Coast and mid 60s to mid 70s
inland. Lows will mostly be in the upper 40s and 50s.
.LONG TERM...Extended models in good agreement Thursday and Friday
with the upper level ridge offshore moving over the area. 500 mb
heights rising into the lower 580 dms. The low level flow will
remain onshore both days. High temperatures will be a few degrees
warmer both days compared to the short term with with 70s and lower
80s over the interior. With the onshore flow highs on the Coast
will remain in the 60s.
Model solutions inconsistent for the weekend with the GFs building
another ridge over the area for Sunday while the ECMWF brings a
trough into western Washington for the weekend with a weak
shortwave. The Canadian model is a compromise between the GFS and
ECMWF. The ECMWF solution has remained consistent for a few runs
while the ridging on the GFS is a somewhat new solution. The
forecast is more in line with the ECMWF solution at this point and
will stick with that idea in this package with mostly
cloudy/partly sunny skies and a slight chance of showers at some
point over the weekend. Highs will cool back down to near
normal, 60s to mid 70s. Felton
.AVIATION...Areas of morning low clouds otherwise mainly high clouds
today. A weak upper trough will be over the area. There is high
pressure offshore and low pressure inland. Low level onshore flow
will ease Tuesday.
KSEA...A marine push should give Seattle some morning low
clouds, otherwise high clouds this afternoon and evening.
There will be a chance of low clouds again Tuesday morning.
.MARINE...Onshore flow will continue through tonight as marine
air continues to push into Western Washington. There is a weak
weather system over the Pacific Northwest. Onshore flow of
varying degrees will continue through the week as weak weather
systems move through the area but high pressure remains over
the offshore waters with low pressure inland.
.CLIMATE...Since records started in 1945 at Seattle-Tacoma airport
there have been 12 years out of the 72 ( 17 percent ) where the
warmest day of the year occurred in June. Two of those 12 years
were 1995 and 1955 which had the warmest on record June 96 degree
In addition to the record tying warmest June days in Seattle ( 96
degrees ) and Olympia ( 98 degrees ) and the record setting
warmest June day on record at Hoquiam on Saturday ( 91 degrees )
it was also hot in the mountains. The high of 88 degrees at
Paradise on Mount Rainier on Sunday was the warmest June day on
record there breaking the old record of 85 degrees set on June
1st, 1986. Records started at Paradise 100 years ago. Felton
PZ...Gale Warning until midnight PDT tonight for Central U.S. Waters
Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
Juan De Fuca.
Small Craft Advisory until midnight PDT tonight for Coastal
Waters From Cape Flattery To James Island 10 To 60 Nm-
Coastal Waters From James Island To Point Grenville 10 To
60 Nm-West Entrance U.S. Waters Strait Of Juan De Fuca.
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