textproduct: Seattle/Tacoma

SYNOPSIS

High pressure will slowly shift inland over western Washington today ahead of a weak and mostly dry frontal system that will swing inland on Friday. High pressure will rebound over the western US over the weekend and into next week, bringing drier and warmer conditions to the region. Chances for light rain will increase towards the middle of next week as an upper low drops from the Gulf of Alaska.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

Satellite imagery this afternoon shows widespread stratus generally north of Tacoma holding strong, while areas along the coast and across the south Sound have eroded out of the clouds for now. As high pressure slowly shifts inland today into tomorrow, onshore flow will keep clouds present for much of the area, limiting most high temperatures across the area to the 60s. Areas that have broken out of the clouds may see temperatures peak closer to 70 degrees later this afternoon, but confidence remains low over how much of the marine stratus layer will erode this afternoon. Another round of stratus is expected to expand inland over the region tonight as onshore flow continues.

A weak, dissipating frontal system will approach the region on Friday, bringing little more than light rain along the Pacific Coast and potential for drizzle through the stratus layer. Increased onshore flow from this weak system will bring extra cloud cover that will lower temperatures a few degrees from today.

High pressure will quickly rebound over the western US on Saturday, bringing in warmer and drier conditions with plenty of sun breaks and highs in the upper 60s to mid 70s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Ensembles remain in good agreement that high pressure will remain situated over the western US through Monday, but models begin showing a large variance in solutions later Tuesday and beyond. A weak system along the periphery of the ridge will bring in extra cloud cover on Sunday alongside a slight chance for rain along the Northern Coast, with highs mostly topping out below 70 degrees. The ridge will build back into western Washington on Monday, allowing for sunny skies and highs in the upper 60s to mid 70s. Conditions will warm a few degrees into Tuesday as high pressure maintains warm and dry conditions across western Washington.

Ensembles struggle to depict the track of a low pressure system mid week, with some members bringing the trough onshore across the Pacific Northwest while other members have the low stalling offshore. Temperatures look to remain warm, but the upper trough may start to reintroduce some light precipitation chances to portions of the area.

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AVIATION

High pressure will shift inland tonight with dry and stable conditions. Low clouds continue to scatter with VFR conditions expected. A weak trough will pass through western WA on Friday with increasing S/SW winds 10-15 kt 18-00z.

KSEA...VFR conditions tonight with S/SW wind around 5 kt. SW winds increasing to 10-15 kt 18z Friday.

MARINE

Light onshore flow tonight. A weak front will cross the waters on Friday. High pressure will rebuild this weekend for onshore flow. SCA winds possible through the Strait of Juan de Fuca during the afternoon and evening hours.

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HYDROLOGY

The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.