textproduct: Seattle/Tacoma

SYNOPSIS

Weak high pressure remains in place today, flattening and becoming more zonal over the weekend. Onshore flow will increase over the next several days. A system arriving on Memorial Day will bring widespread rain and cooler temperatures to the region. The rest of the front will move through on Tuesday, keeping showers in the forecast. Weak ridging is possible through the second half of the week.

SHORT TERM /TODAY THROUGH SUNDAY/

Satellite imagery early this morning shows the stratus along the coast, remaining generally clear in through Puget Sound. Temperatures are in the low to mid 50s. Weak high pressure aloft will transition to more zonal, onshore flow through the weekend. This will bring in morning marine stratus clouds that reach the interior by Saturday and Sunday. Afternoon sun is expected as the stratus erodes. Expect highs in the upper 60s to low 70s. The onshore flow will also strengthen the westerly winds through the Strait of Juan de Fuca over the weekend.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

The zonal flow will open the door to the next system arriving late Sunday night into Monday. This one will bring about more widespread rain to western Washington and temperatures that are unlikely to get much warmer than the low 60s by Monday. While not a final forecast, indications of what the QPF could look like at this point suggest around a quarter to three tenths of an inch of rain in the lowlands and one to one and a half inches of rain in the Cascades and Olympics from Sunday afternoon through Tuesday afternoon. After this system moves through, temperatures will only slightly increase into the upper 60s.

Beyond Wednesday, there is uncertainty as to whether a trough or ridge rebuilds. The ensembles are split with no real consensus at this point and looks to generally remain dry in the extended forecast.

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AVIATION

West-northwest flow aloft through today with weak ridging over the area. Onshore flow continues at the surface. VFR conditions for the interior early this morning, with LIFR/IFR along the coast. LIFR/IFR stratus will move into the Southwest Interior this morning, and expected to mainly remain from SHN westwards. Vsbys may also lower towards less than 1SM for the immediate coast at times this morning. Stratus will then clear late morning into midday with VFR conditions for the afternoon. Light winds this morning will increase from the N/NW this afternoon.

KSEA...VFR conditions through the period. Stratus expected to remain well SW of the terminal this morning, with less than a 10% chance of IFR cigs this morning. Mainly NE winds this morning will increase from the NW this afternoon ranging 5 to 10 kts. JD

MARINE

Onshore flow continues into the weekend with high pressure offshore and lower pressure inland. Northwest winds will remain over the Coastal Waters through the weekend. West winds increase through the Strait of Juan de Fuca this evening, resulting in SCA gusts to 25 kts into tonight. A stronger west push through the Strait of Juan de Fuca is expected Saturday night, with the potential for localized gales through the Strait during this period. At this time, the probabilities for gale force wind gusts peaks around 75% for the central and eastern Strait. Winds will then ease once again on Sunday. A weather system traverses the area on Monday, bringing widespread SCA wind gusts to much of the area waters.

Seas will mainly remain 5 to 9 feet through this weekend, with the largest and steepest waves over the offshore waters. Dominant periods will be around 8 to 9 seconds through Sunday. Waves increase to 10 to 13 feet Monday into Tuesday with the next weather system. JD

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...Small Craft Advisory until 5 AM PDT early this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 11 AM PDT this morning for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.