SYNOPSIS
An upper level trough will swing across the Pacific Northwest tonight and Sunday. Upper level troughing will then remain the dominant influence over the region through much of the next week, bringing increased onshore flow, cooler temperatures, and some showers at times.

SHORT TERM /TONIGHT THROUGH TUESDAY/
Smoke aloft continues to stream into western Washington from the south, producing hazy skies across much of the region this afternoon. Latest satellite imagery shows some mid to high cloud cover also moving in from the south, associated with some very weak echoes on radar. The airmass remains dry in the low levels, so do not expect to see much in the way of precipitation to make it to the ground. A slight chance of isolated thunderstorms remains for portions of the south Sound and Cascades through tonight, though latest probabilistic guidance still shows less than a 10 percent probability of occurrence - so confidence in this remains low.

The thickness of the smoke aloft has been impacting temperatures across the region this afternoon. Current temperatures are trending in the 70s across the interior and the 80s across the Cascades. With smoke continuing to stream in overhead, have lowered afternoon highs a few degrees and have them generally topping out in the low 80s for the interior lowlands. Warmer conditions are still expected for the Cascades, with temperatures expected to top out in the upper 80s to low 90s in some spots.

An upper level trough moving into Oregon today will swing its axis across the Pacific Northwest on Sunday, bringing increased onshore flow and slightly cooler temperatures to western Washington. Stratus will push a little bit further inland along the coast on Sunday morning where afternoon temperatures are generally on track to top out in the mid to upper 60s. Temperatures across the interior will start to cool a few degrees as well, topping out in the upper 70s to low 80s. Elevated smoke aloft will continue to stream into the region on Sunday, however expect slow improvement through the day. A chance of showers and isolated thunderstorms remains possible for the Cascades on Sunday afternoon, however confidence in occurrence again remains low.

Flow aloft will transition to more zonal on Monday, promoting increased onshore flow and allowing for stratus to push further inland into the interior. Temperatures will cool as a result with afternoon highs expected to be in the 60s and 70s. Cooler conditions will continue into Tuesday, before an upper level trough approaches the region Tuesday afternoon and evening.

LONG TERM /WEDNESDAY THROUGH SATURDAY/
Guidance generally hints at upper level troughing remaining the dominant influence across the region through much of the long term period. The aforementioned upper trough digging offshore on Tuesday looks to swing across the region on Wednesday and bring more widespread shower activity back to western Washington. The trough looks to move off to the east by Thursday afternoon, allowing for conditions across western Washington to briefly dry back out. Guidance then hints at another trough deepening over the northeastern Pacific and approaching the area over the weekend. The overall pattern will keep temperatures trending close to just below normal through much of the extended period. 14

AVIATION
Weak upper level trough moving through Western Washington Sunday. Southerly flow aloft becoming southwesterly late Sunday morning and westerly later Sunday. The change in the flow aloft will push the elevated smoke east of the area Sunday night. Onshore flow in the lower levels increasing Sunday.

IFR ceilings along the coast tonight with the stratus spreading inland Sunday morning reaching the Puget Sound area 12z-14z.
Ceilings improving slowly later Sunday morning. Skies clearing over the interior 19z-21z with MVFR ceilings continuing along the coast.

KSEA...Elevated smoke aloft through Sunday. IFR ceilings developing 12z-14z. Ceilings lifting to MVFR by late morning with the clouds scattering out 19z-21z. Southwest winds 4 to 8 knots.
Felton

MARINE
Thermally induced trough inland tonight with low level onshore flow. Onshore flow strengthening Sunday with small craft advisory westerly winds in the Central and Eastern Strait of Juan de Fuca Sunday evening. A weak front cross the waters on Monday.
Weak low pressure moves through the Coastal Waters Tuesday and Wednesday. Wave Heights generally 4 to 7 feet through the period.
33/Felton

FIRE WEATHER
Hot, dry, and unstable conditions will continue through this evening for the Olympic zones 652/661 and Cascade zones 658/659 - where a Red Flag Warning remains in effect.
Elevated smoke and some mid to high cloud cover moving into the region from the south has aided portions of the southern Cascades from bottoming out into critical RH levels this afternoon, however latest observations are still showing RHs in the low to mid 20s across portions of the North Cascades. Isolated thunderstorms will remain possible across portions of the South Cascades through this evening, though confidence in this remains low with probabilistic guidance still only showing less than a 10% chance of occurrence.

Cooler and more moist air will make a return area-wide on Sunday, though isolated thunderstorms will again be possible across the Cascades Sunday afternoon into evening as an upper trough swings through. General upper troughing pattern setting up next week will bring increased onshore flow and cloud cover, better humidity recoveries, and the potential of some wetting rains by mid-week - which will help mitigate fire weather conditions. 14

SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...Small Craft Advisory from 6 PM Sunday to 6 AM PDT Monday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.