textproduct: Seattle/Tacoma

SYNOPSIS

Weak upper level trough tonight will move east Sunday. Weak upper level ridging Sunday and Monday before shifting eastward Tuesday. Another upper level trough will move over Western Washington Wednesday and remain through the end of the week.

SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/

Weak upper-level troughing tonight with continued low-level onshore flow. Areas of marine stratus looks to develop into the early morning hours on Sunday. Surface winds are favored to become light - but gusts upwards of 15 to 20 mph are possible for Whidbey Island after midnight. Overnight lows are forecast to fall into the mid 40s to mid 50s.

The aforementioned upper-trough will push east of the Cascades on Sunday. As a result, weak ridging looks to replace it Sunday into Monday. Afternoon highs are forecast around seasonal averages on Sunday with values in the 70s to near 80 F throughout the lowlands. Coastal areas will likely remain in the 60s. A noticeable warm is in the offing on Monday with forecast highs 5-8 degrees above normal. Temperatures ranging between the upper 70s to mid 80s. The coast remaining the cool spot again, with highs in the 60s. Overnight lows are forecast in the upper 40s to mid 50s for both Sunday night and Monday night. Upper-level ridge favored to move east by Monday evening.

LONG TERM /TUESDAY THROUGH SATURDAY/

An upper level trough and associated front will approach the coast Tuesday. Increasing onshore flow during the day Tuesday will drop highs in the interior back into the 70s. Highs on the coast in the lower to mid 60s. Upper level trough and associated front moving through Wednesday for mostly cloudy skies and increased PoPs for most of the area. Highest probability for measurable precipitation appears to be over the North Cascades at this time. Highs continue to cool with 60s and lower 70s in the forecast. Weak upper level trough hanging around Wednesday night through the end of the week. Low level onshore flow making for a morning clouds afternoon sunshine scenario Thursday through Saturday. Highs remaining near or a couple of degrees below normal, in the upper 60s to mid 70s over the interior and mid 60s on the coast.

AVIATION

Mostly clear/VFR conditions this evening as a cold front will pass through dry. Low clouds will return tonight, with the highest chances near the coast, and a 30-40% chance of it making it into Puget Sound. MVFR is the favored ceiling category, with timing between 12-18Z in the morning (coastal areas will see it begin a few hours earlier and hold a couple hours after). West to northwest winds will be the dominant direction through the TAF period. Strong onshore flow this evening along the Strait of Juan de Fuca with gusts to 20 kt possible through Sunday morning. This will result in northwesterly winds spilling into Puget Sound terminals this evening, then shifting northeasterly with gusts to 15-20 kt through early Sunday morning.

KSEA...VFR through the evening. Stratus returns Sunday morning with a 30-40% chance the ceilings will be in the MVFR category between 12-18Z. Winds northwest to northeast overnight 7-10 kt gusting to 15-20 kt through the evening, shifting back to the northwest during the day Sunday. Few gusts to 20 kt possible in the afternoon.

AH/HPR

MARINE

A rather stagnant weather pattern will persist over Washington's waters into next week. Broad high pressure over the northeast Pacific and lower pressure inland will keep an onshore flow pattern. This will result in increased westerlies through the Strait of Juan de Fuca each evening, some having the potential to reach small craft thresholds. There is high confidence (greater than 70%) for strong westerlies this evening through the Strait. Guidance also suggests there is a 70% chance or higher for small craft winds to reach Admiralty Inlet this evening as well. Therefore, small craft advisories are set to go into effect the Central/East Strait and Admiralty Inlet later this evening. Winds will also increase for the lower coastal waters late this evening to advisory thresholds. There is high confidence (75-85%) for increased northwesterly winds Sunday evening across all portions of the coastal waters, and the advisory has been extended. Long term guidance highlights a 60-90% chance for small craft winds through the Strait next week, likely requiring additional headlines. A few weak fronts will move through the waters throughout the week, but high pressure is expected to rebuild quickly over the waters behind the fronts.

Seas will build late this evening to 6-8 ft and up to 10 ft through Monday. Seas will gradually subside below 10 ft on Tuesday to 4-6 ft.

FIRE WEATHER

Continued low-level onshore flow well into next week. This will keep good overnight relative humidity recoveries in the forecast and help subdue fire weather concerns despite the warmer temperatures. Another front in the middle of next week will bring a chance of rain to the area keeping fire weather concerns at a minimum.

We already have small fires cropping up in the Olympics and Cascades even without elevated fire weather conditions. If you are in the mountains the next few days please be extra careful.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 3 AM PDT Sunday for Admiralty Inlet- Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 11 PM PDT Sunday for Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.