Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS66 KSEW 250950

Area Forecast Discussion
National Weather Service Seattle WA
250 AM PDT SAT JUN 25 2016

.SYNOPSIS...A weak upper ridge over the Pacific Northwest will
bring dry weather today, with morning clouds giving way to
sunshine. Dry weather should continue Sunday through next week,
with light west to southwest flow aloft and onshore low level
flow. Days should be mostly sunny and a little warmer than
normal with highs in the 70s to lower 80s.


.SHORT TERM...The upper trough that brought showery weather to
Western Washington the past couple days has moved into north
central Montana, and there is a weak upper ridge over Western
Washington early this morning. The air mass is still moist though,
especially in the lower 6000 ft or so. Skies were mainly cloudy at
2 am with temperatures in the 50s.

The weak upper ridge will move east of the Cascades today, but it
will be followed by rather dry westerly flow aloft. The weak
frontal system that extends southwest from Vancouver Island will
weaken further and move by to our north. The low level moisture
will dry also, so mainly cloudy skies this morning should
gradually give way to partly to mostly sunny skies during the
afternoon for the lowlands. There could be just some spotty light
showers over the Cascades this afternoon.

Light westerly flow aloft will continue tonight and Sunday, and an
upper ridge will start building over the Pacific Northwest. The
500 mb heights over Western Washington will rise to around 5820
meters Sunday afternoon, and it will be a sunny day with highs
into the lower 80s across much of the Puget Sound region and south

The upper ridge will build slowly as it moves into the Rocky
Mountains on Monday. The flow will back to southwesterly, and the
lower atmosphere will warm a bit more. It should be another sunny
day and 1 to 3 degrees warmer in the interior lowlands. Onshore
flow will strengthen a bit at the coast, and it should be around 1
to 3 degrees cooler there. The GFS does show spotty showers
developing over the mountains Monday afternoon, but the ECMWF
limits moisture and keeps the weather dry. We are staying with a
dry forecast for now. McDonnal

.LONG TERM...Models agree that light west or southwest flow aloft
will prevail Tuesday through Friday, with weak to moderate onshore
flow at the surface. This should be a period of fair weather, with
highs generally in the 70s to lower 80s and lows in the 50s to
lower 60s. McDonnal


.AVIATION...High pressure aloft will gradually build over Western
Washington today and tonight with westerly flow aloft. At the
surface, onshore flow will prevail with high pressure offshore and
lower pressure inland. The air mass is moist and stable. Drying
will occur later today with clouds scattering most areas in the
afternoon or early evening.

KSEA...Low clouds will lift and breakup this afternoon. Clouds
will probably scatter entirely late in the afternoon. Southerly
wind 4-8 knots will becoming northerly this afternoon. Schneider


.MARINE...Onshore flow will prevail for the next several days with
high pressure offshore and lower pressure inland. Small craft
advisory west winds are likely each evening in the Central and
Eastern Strait of Juan De Fuca. There will also be small craft
advisory northwest winds at times for the Coastal waters, mainly
late afternoons and evenings. Schneider


.SEW Watches/Warnings/Advisories...
PZ...Small Craft Advisory until 5 AM PDT early this morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 2 PM this afternoon to 3 AM PDT Sunday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to midnight PDT
     tonight for Coastal Waters From James Island To Point
     Grenville Out 10 Nm-Coastal Waters From Point Grenville To
     Cape Shoalwater Out 10 Nm.



You can see an illustrated version of this discussion at is the U.S. government's official web portal to all federal, state and local government web resources and services.