textproduct: Seattle/Tacoma

SYNOPSIS

A weak atmospheric river will produce periods of moderate to locally heavy rain into tonight. High pressure aloft begins to rebuild into the region on Tuesday and will persist through the remainder of the week for an extended stretch of dry conditions.

SHORT TERM /TODAY THROUGH WEDNESDAY/

A stalled frontal boundary continued to produce moderate to locally heavy rainfall across the northwest half of the CWA overnight along with gusty winds coast and North Interior areas. As atmospheric rivers go, this one has been thankfully on the weaker side and has thus limited the threat of flooding to the Skokomish River so far. More on this can be found in the hydrology discussion. Periods of rain will continue to be largely focused on the northwest half of Western Washington today before the frontal boundary responsible for it finally lifts northward tonight in response to a broad upper ridge expanding northward into the region. This will dry most of the area out by Tuesday morning. The region will remain in a very mild air mass on Tuesday and, despite persistent cloud cover much of the day, high temperatures in the mid (and perhaps upper) 50s will tease a few records around the area. An upper level ridge remains in control into Wednesday and, as alluded to a couple nights ago, one last approaching front will mostly likely get washed out before it ever manages to make it onshore.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

A high amplitude upper ridge axis takes up residence just offshore Thursday into at least the early portion of the weekend. The only real forecast challenge during the period will be high temperatures and day-to-day fog coverage in the interior lowlands. Low level offshore flow reaches a zenith in the Friday to Saturday period as a 1040-ish millibar surface high settles over the interior of British Columbia. The extended portion of the forecast will likely be a beautiful period in the mountains as well as along the coast. It wouldn't be too surprising to see some coastal areas make a run at 60 degrees on Friday. After what transpired in December, perhaps we've earned a welcome break. 27

AVIATION

Southwest flow aloft will transition more westerly tonight into early Tuesday as an upper ridge builds further into Western Washington. VFR/MVFR cigs early this morning with rain primarily from King County northwards and along the Olympic Peninsula. Predominantly low-end VFR to MVFR for much of the area through today, with IFR/LIFR confined to the coast. Cigs will lower further again tonight. Gusty southerly winds will continue, especially for the coast, and terminals from PAE northwards. Gusts may reach 30 to 35 kts at times for BLI this morning. Otherwise, winds will slowly subside tonight.

KSEA...Low-end VFR conditions early this morning. Cigs are expected to range from low-end VFR to MVFR through this afternoon (mainly between 020-035). Cigs may lower further towards IFR late tonight into Tuesday morning. S/SW surface winds ranging 8 to 12 kts with occasional gusts to 15 to 20 kts through this afternoon. JD

MARINE

A stalled frontal boundary across the northern half of the waters will shift northward later today and weaken as surface high pressure expands northward across the waters. Winds will gradually ease across the waters through the day today. Broad surface ridging will remain across the waters into midweek and a frontal boundary will dissipate well offshore Wednesday afternoon. Strong surface high pressure over the offshore waters will build into the interior of British Columbia on Thursday as thermally induced low pressure expands northward along the Oregon coast. This will lead to a period of offshore flow toward the end of the week. Apart from easterlies near gaps in coastal terrain, this should be a relatively quiet period in terms of wind across area waters.

Coastal seas will remain in double digits through Tuesday. They may briefly dip below 10 feet Tuesday night or early Wednesday before another decaying swell train pushes seas back above 10 feet. Seas will then subside to 5 to 7 feet at the conclusion of the forecast period. 27

HYDROLOGY

Steadier rain continues, mainly for the Olympics and North Cascades. Additional precipitation amounts are expected to range between 1 to 3 inches for the Cascades of Skagit and Whatcom Counties, with 1 to 2 inches for the Cascades of Snohomish County and the Olympics. Snow levels also range between 7000 to 8000 feet. The Skokomish River continues to rise, and is forecast to approach (and potentially exceed) moderate flood stage this morning. Additional rises on rivers are expected, mainly in the aforementioned locations. The Skagit River in particular continues to be monitored for potential minor river flooding over the next day or two. Drier weather is then expected later Tuesday through next weekend, with no additional flooding expected. JD

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 4 AM PST Tuesday for Grays Harbor Bar.

Gale Warning until 6 AM PST early this morning for Admiralty Inlet-Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm- East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands-West Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 6 AM this morning to 10 PM PST this evening for West Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 10 AM PST this morning for Central U.S. Waters Strait Of Juan De Fuca-Puget Sound and Hood Canal.

Small Craft Advisory from 6 AM this morning to 1 PM PST this afternoon for Admiralty Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.

Small Craft Advisory from 6 AM this morning to 4 AM PST Tuesday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.