textproduct: Seattle/Tacoma

SYNOPSIS

A strong storm will bring wind, rain and high elevation snow today. Showers and a convergence zone will follow on Wednesday. Drier and slightly warmer weather will prevail into the end of the week. Rain increases by Monday with a trough.

SHORT TERM /TODAY THROUGH THURSDAY/

Precipitation moving through the area this morning having some isolated lightning strikes embedded in some of the showers. May continue to see some isolated lightning for the next hour or two before the main precipitation band shifts eastward. This system moving in is a Little bit quicker than the previous forecast expected.

A strong Pacific storm system continues to move into the region today with active weather across western WA. This system is tied to a deep, 990 mb, low that will pass over northern Vancouver Island later this morning. With the passing of the low, we will see tighter pressure gradients over western WA with a period of stronger south winds this morning and afternoon. Highest winds will be along the coast and over the north interior where gusts to 40-50 mph will occur - a Wind Advisory is in effect. Expect gusts to 30-40 mph elsewhere with winds easing late this afternoon and evening. Up in the mountains, snow levels will be rising through the day but we may see a brief period of heavy snow at Mount Baker and the north Cascades this morning. Rainfall/QPF is not too heavy otherwise. Rivers may see small rises but additional flooding is not expected.

We remain under moderate onshore flow on Wednesday with high pressure offshore and low pressure to our north. Still plenty of moisture over the area with additional showers expected. Snow levels will be lower, around 2500 ft, with snow in the Cascades and passes. Showers may be enhanced with a Puget Sound Convergence Zone over Snohomish County. The air mass will be slightly unstable with a chance of thunderstorms too.

High pressure starts to build inland on Thursday for a trend toward drier weather. 33

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

High pressure and offshore flow will lead to a couple of dry and slightly warmer days moving into the end of the week and weekend. Highs on Friday and Saturday will be in the 50s to lower 60s. A trough kicks the ridge inland on Sunday with increasing clouds and a chance of showers over western WA. Monday is wetter (and cooler) as the trough shifts inland and over WA. 33

AVIATION

Strong southwest flow aloft as a frontal system affects the area today. Widespread MVFR conditions - ceilings and visibilities - with rain this morning. Ceilings are expected to generally improve after 18z with most locations reaching 3-3.5K feet between 00-03Z this evening. Strengthening south to southeasterly surface winds will peak this afternoon ahead of the cold front, front becoming southwesterly behind the front this evening.

KSEA...MVFR ceilings - with 2-3SM visibilities and persistent rain this morning. Ceilings look to start to gradually improve late this afternoon, lifting to low end VFR levels behind the front around 01- 03Z. Winds will back to the south through the remainder of the morning, increasing to 7 to 10 knots and then 15 to 25 knots between 21Z and 00Z with occasional gusts of 30 to 35 knots ahead of the approaching front. Sustained winds will ease late this evening, but remain gusty through 08Z.

MARINE

A vigorous frontal system will sweep across across the waters late this afternoon into this evening. Strong onshore flow will settle in behind the front. Gales are expected all waters with coastal seas building well into the double digits this afternoon and tonight and persisting into Wednesday. Surface ridging will begin to rebuild across the waters on Thursday and remain in place into Friday before another front approaches over the weekend. Seas will slowly subside to 6-8 feet Thursday and 5-7 feet toward the weekend.

HYDROLOGY

River flooding in not expected over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory until 6 PM PDT this evening for Island County- Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-Port Townsend Area-San Juan County.

Wind Advisory until 3 PM PDT Wednesday for Grays Harbor County Coast-Northern Washington Coast.

PZ...Small Craft Advisory until 5 AM PDT Wednesday for Grays Harbor Bar.

Gale Warning until 11 PM PDT this evening 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-Puget Sound and Hood Canal-West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca.

Gale Warning until 9 PM PDT this evening for Admiralty Inlet- East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.