textproduct: Seattle/Tacoma

UPDATE

Forecast on track this evening. Previous discussion follows with updated aviation section.

SYNOPSIS

Cloudy and mild conditions will continue through the weekend and into early next week as high pressure remains situated over the West. A weak system will clip the northern portion of western Washington on Sunday, bringing little more than drizzle and overcast skies. Forecast confidence decreases into the middle of next week, with chances for light rain through the remainder of the week.

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/

A weak splitting frontal system will continue to progress eastward today, bringing in little more than clouds and isolated drizzle to western Washington. Temperatures have stayed on the cool side this morning, with some sun breaks this afternoon helping temperatures to peak in the low to mid 60s across the lowlands.

High pressure will build inland behind the frontal passage tonight into Saturday, with persistent cloudy skies and drier conditions. Highs will warm a few degrees, topping out in the upper 60s to low 70s.

The upper level ridge will shift east of the Cascades by Saturday night, with southwest flow aloft filling in behind. Onshore flow will bring increased clouds Sunday as a weak system to the north skirts Vancouver Island. Chances for light rain will likely be confined to the northwestern coast of the Olympic Peninsula and North Cascades, with overcast conditions elsewhere. The increased cloud cover will lower temperatures a few degrees on Sunday, with highs mostly in the 60s.

LONG TERM /MONDAY THROUGH FRIDAY/

Models remain in good agreement over high pressure building over the western US early next week, allowing for more sunbreaks and warmer conditions on Monday and Tuesday. While some ensemble members keep western Washington dry through the first half of next week, some members are picking up on a potential cutoff low developing offshore and quickly swinging inland on Tuesday, with potential for showers forming mainly over higher terrain.

Forecast confidence decreases into the middle of next week, with ensembles showing a large variance of possible weather systems moving into the area. Chances for light rain remain across the region through the end of next week, with snow levels remaining above 6000-7000 feet.

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AVIATION

Upper level ridge over the area shifting east northwesterly flow aloft becoming southwesterly Saturday morning. Light flow in the lower levels. VFR conditions except MVFR along the coast. Areas of MVFR ceilings developing over the interior 11z-14z dissipating after 19z.

KSEA...VFR conditions with MVFR ceilings developing around 12z. VFR ceilings again after 19z. Southerly winds 4 to 8 knots becoming northwest after 20z. Felton

MARINE

A weak front is pushing across area waters this evening with little to no potential for headlines. Reoccurring spells of onshore flow into early next week. The next best chance of SCA occuring are for the central/eastern strait due to a westerly push on Sunday evening. Much uncertainty going into next week but, a more organized system is set to arrive by Wednesday. Seas 3 to 6 ft tonight through early next week.

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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.