textproduct: Seattle/Tacoma

SYNOPSIS

A weak ridge of high pressure will bring warmer and drier conditions to Western Washington into Tuesday. A weak frontal system moves through on Wednesday with cooler temperatures and a little rain for parts of the area. Onshore flow will keep temperatures near normal for the second half of the week with areas of night and morning clouds.

SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/

Mostly clear skies this afternoon with temperatures ranging in the 60s and 70s. Stratus along the coast will move onshore along the immediate coastline tonight, but expected to mainly be confined to Grays Harbor County and Strait of Juan de Fuca with rather weak onshore flow. Temperatures warm further on Monday as weak ridging builds further into Western Washington. High temperatures on Monday range in the mid 70s to mid 80s, with upper 60s along the immediate coast.

Weak ridging continues over the Pacific Northwest on Tuesday, however, troughing will approach BC late Tuesday, resulting in increase high clouds into the afternoon over Western Washington. Temperatures will cool a few degrees on Tuesday due to increase high cloud coverage and onshore flow. Minor HeatRisk is expected both Monday and Tuesday.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

A weak frontal system will move across Western Washington Tuesday night through Wednesday resulting in cooler temperatures and increased cloud cover. Precipitation potential also increases during this period, particularly for the Cascades, Olympics, and lowland areas from King County northwards. However, any precipitation is expected to mainly be light (less than 0.10" for most). Weak upper level ridging begins to build back into the area Wednesday night and Thursday. Another front then looks to weaken offshore on Friday, bringing minimal precipitation chances, mainly to the Olympic Peninsula. Onshore flow expected to continue the second half of the week into next weekend with strong upper ridging over the Southwest and troughing over British Columbia. This will likely result in periods of morning clouds, afternoon sunshine, and relatively seasonal temperatures. JD

AVIATION

VFR conditions across the terminals as high pressure builds under a ridge with weak flow aloft. NW winds will continue across most terminals through the evening at 6-12 kt with gusts to 20 kt, then transition to the northeast 5-10 kt overnight. For Monday morning, the coast has the highest likelihood of seeing MVFR/IFR stratus in the morning with a 50-60% chance between 12 and 18Z. Probabilities for remaining interior terminals remain too low to introduce BKN in the 06Z TAF package (10-20%) but can't rule out FEW or SCT in the morning around 3,000 ft, before clearing out. Winds turn back to the NW 5-10 kt but likelihood of gusts is low for Monday.

KSEA...VFR likely to persist through the TAF period. NW winds 6-12 kt gusting to 20 kt will diminish to around 5 kt this evening, shifting to the northeast before switching back to the NW in the afternoon at 5-10 kt.

HPR

MARINE

A rather stagnant weather pattern will continue for Washington's waters through the forecast period. Broad high pressure over the northeast Pacific and lower pressure inland will maintain a pattern of onshore flow. Small craft conditions will be present in the coastal waters this afternoon through tomorrow morning due to the northwest winds. This pattern will result in increased westerly winds through the Strait of Juan de Fuca each evening. Probabilities are increasing (60-90%) for winds through the Strait of Juan de Fuca to reach small craft advisory criteria Monday afternoon. These conditions continue through at least Tuesday morning with similar confidence for a return Tuesday afternoon. A weak front will move over the waters Tuesday evening/Wednesday morning. This will slightly weaken high pressure over the waters, but it is expected to quickly rebuild behind the front.

FIRE WEATHER

Low-level onshore flow will continue through the week. This will keep good overnight relative humidity recoveries in the forecast and help subdue fire weather concerns despite somewhat warmer temperatures through Tuesday. In addition, a weakening front will move across the area Tuesday night into Wednesday, bringing the chance for light rain to portions of Western Washington. JD

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 2 PM Monday to 8 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 8 AM PDT Monday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.