textproduct: Seattle/Tacoma

SYNOPSIS

One more warm day in the interior today, then cooler conditions on Wednesday due to increasing onshore flow. Onshore flow will prevail through the weekend with near average temperatures and a chance of mountain showers. Warmer and drier conditions are forecast early next week with broad high pressure.

SHORT TERM /TODAY THROUGH THURSDAY/

An upper level ridge will slide farther east and inland today, while a deep upper low spins off northern B.C. Across western WA, mostly clear skies this morning with temperatures in the 50s to lower 60s. Overall, temperatures will be cooler across the board today (compared to yesterday) although highs will still track above normal in the interior - mid/upper 70s to around 80. NW winds will keep the coast in the 60s. The low off B.C. will send a weak/dry front inland tonight/early Wednesday with increasing onshore flow expected. With the flow turning onshore, smoke from nearby Canadian wildfires will remain north and east of western WA.

Low pressure will shift inland into B.C./Alberta Wednesday and Thursday with ongoing onshore flow across western WA. Temperatures will track close to seasonal averages.

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LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Through the period, low pressure will sag south offshore while strong high pressure builds over the Southwest. This puts western WA under (slightly) moist SW flow with a chance of showers over the Olympics and North Cascades. The probability of thunderstorms is low or less than 10 percent. Heights build early next week as ridge shifts north and expands over the CONUS. Temperatures will nudge warmer than average with interior highs in the lower to mid 80s, and 70s along the coast.

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AVIATION

A closed low over central British Columbia will maintain west/southwesterly flow over the area today. Stratus continues push inland across western Washington but has likely reached its maximum extent this morning as of 15Z. Under the stratus, MVFR to IFR cigs are being observed with a thickness of around 500 ft over the Seattle metro. This should allow the stratus to burn off within the next few hours here this morning, or around 18-19Z. Otherwise, VFR conditions will prevail through the remainder of the day after the stratus burns off. Widespread MVFR cigs look to return Wednesday morning, with highest confidence (80-90% chance) along the coast. As for the interior terminals, there is a 50-85% chance after 10z Wednesday, with highest chances for the Kitsap Peninsula. IFR cigs will also be possible along the Kitsap Peninsula and coast.

Generally SW winds along the interior terminals and WNW winds along the coast and Strait of Juan de Fuca. Expect winds to shift NW in the afternoon along central Puget Sound terminals as early as 23z. Breezy conditions this morning will continue today along the Strait of Juan de Fuca with gusts to 20-25 kt likely.

KSEA...VFR conditions will prevail today. Confidence is increasing for MVFR cigs to return after around 10z Wed, with current probabilities around 40-60%. There will be a 10-15% chance of IFR cigs as well, between around 13-16Z Wed. Light SW winds this morning will shift to NW between 23z-01z at 5-7 kt, then shifting NE in the evening. Guidance suggests southerly winds will return after 09z Wednesday.

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MARINE

Broad high pressure will continue over area waters through Thursday. A weak frontal system will move across the waters late tonight into early Wednesday. However, high pressure is expected to immediately rebuild behind the front. High pressure will weaken late in the week as a low pressure system prepares to swing south towards area waters. Onshore flow will continue the rest of the week through Strait of Juan de Fuca. A small craft advisory continues through early this afternoon for the central and eastern portions. A stronger push of westerlies is expected this afternoon through the Strait of Juan de Fuca. Later this afternoon winds strengthen and a Gale Warning will be in effect. Small craft winds will also spill into Admiralty Inlet this afternoon and a small craft advisory has been issued. Another strong push is expected Wednesday afternoon. Latest guidance suggests there is a 50-60% chance of gales through the Strait of Juan de Fuca, and a Gale Watch has been issued for Wednesday afternoon. Additional headlines are possible throughout the rest of the week.

Seas expected to remain below 10 ft through the weekend. Portions of the coastal waters may see steep seas on Wednesday/Thursday as seas build to 6-8 ft with a dominant period of 7-8 seconds.

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FIRE WEATHER

The overall fire weather threat will remain low across western WA with onshore flow and higher humidities across the area. Warmer and drier conditions are forecast early next week although minimum humidities are not forecast to reach critical thresholds.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 2 PM PDT this afternoon for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning from 2 PM this afternoon to 8 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Watch from Wednesday afternoon through late Wednesday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 1 PM this afternoon to 3 AM PDT Wednesday for Admiralty Inlet.