textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge offshore weakening tonight. Increasing clouds Monday as a weak system moves through the ridge. Ridge rebuilding Monday night, moving inland Tuesday. Splitting system arriving Wednesday. More consolidated systems moving through Western Washington at the end of the week.

SHORT TERM /TODAY THROUGH TUESDAY/

Satellite imagery shows narrow high amplitude ridge just offshore this morning. Patchy fog over the South Sound and Northern San Juans otherwise clear skies over the area. Cool temperatures at 2 am/10z with almost all locations in the 20s. Saturday morning and this morning the coldest mornings since the middle of February 2025. Seattle had a low of 20 on February 13th, 2025.

Upper level ridge offshore today giving the area another sunny day. The patchy fog is shallow and will dissipate in the morning. Highs today in the mid 40s.

Upper level ridge weakening tonight. Weakening system currently near 130W will move through the ridge later tonight into Monday. Main impact from this system will be an increase in middle and high level clouds overnight into Monday. Slight chance of rain along the coast Monday. The cloud cover will make for a tricky low temperature forecast Monday morning. Ensemble spreads as much as 10 degrees in some locations. With the skies clear initially temperatures will lower to below freezing in most locations before the cloud cover makes it harder for the temperatures to drop. Lows in the 20s and lower 30s. Highs Monday in the mid and upper 40s.

Upper level ridge rebuilds offshore Monday night and moves inland Tuesday morning. Ridge axis over Eastern Washington Tuesday afternoon. Middle and high level clouds over the area especially Tuesday. Lows in the upper 20s to mid 30s. Highs a couple of degrees either side of 50. Felton

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Extended models showing more agreement this morning. Splitting system moving into Western Washington Tuesday night/Wednesday morning with the ridge axis east of the area. Flow aloft over the Pacific becoming more progressive with weather systems embedded in the southwesterly flow aloft arriving each day Thursday through Saturday. Will have likely pops or higher in the forecast for the first time in two weeks Thursday and Friday. Ensembles pretty evenly split between dry and wet solutions Friday night and Saturday so will have chance pops for those times. The ensembles are trending wetter so won't be surprised if the rain chances increase for Friday night into Saturday in future forecasts. Still some lows in the 30s Wednesday morning with lows in the 40s the rest of the period. Highs near 50 through Thursday then lower to mid 50s Friday and Saturday. Snow levels starting out near 4000 feet Tuesday night into Wednesday with southwesterly flow aloft increasing the snow levels to 5000 to 6000 feet Thursday through Saturday. Felton

AVIATION

A high amplitude ridge will continue to build into the area this morning, with winds shifting from northwest to southwest aloft. VFR conditions prevail across much of the region, with areas of LIFR in freezing fog south of the Puget Sound, including near OLM.

Another round of freezing fog and low stratus will continue to expand this morning once again across the south Sound near OLM (25-35% prob) and CLM. Probabilities are lower for the metro area (15-20%) and given the pattern the past few days, fog remains unlikely there. Winds remain light offshore, but most interior terminals have light and variable winds and will remain like so through the TAF period.

KSEA...VFR conditions with clear skies. Light and variable, though mostly N/NE winds. There's a 15-20% of low stratus, but this remains a low- probability scenario.

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MARINE

Broad high pressure across the northeast Pacific will remain in place through the weekend with generally calm winds. The next period of impactful marine weather doesn't look to arrive until Monday into Tuesday, as a weak frontal system approaches the west coast and brings back increasing southerly winds. A stronger frontal system will approach the waters mid-week, bringing a period of breezy southerlies across the coastal waters.

Seas 3 to 5 ft will continue this weekend, increasing to the 10-15 ft range Tuesday, getting as high as 18-20 feet on Wednesday, and remaining elevated at 9-13 feet through the remainder of next week as systems move back into the area. Larger seas may be possible late next week as systems may develop in the Gulf of Alaska to produce large, long period swells.

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HYDROLOGY

No river flooding the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Cold Weather Advisory until 9 AM PST this morning for City of Seattle-Downtown Everett / Marysville Area-Eastern Kitsap County-Eastside-Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties- Olympia and Southern Puget Sound-Shoreline / Lynnwood / South Everett Area.

PZ...None.