textproduct: Seattle/Tacoma

SYNOPSIS

Increasing low level onshore flow will bring cooler air into Western Washington today with highs 10 to 20 degrees cooler. Upper level ridge centered well offshore with northwesterly flow aloft and light or low level onshore flow will keep temperatures a few degrees above normal along with dry conditions through the weekend. Upper level ridge building early next week producing slightly warmer temperatures.

SHORT TERM /TODAY THROUGH THURSDAY/

Satellite imagery shows stratus filling in along the coast with some middle level clouds over the Northwest Interior. Mostly clear skies elsewhere. Temperatures at 3 am/10z were in the mid 50s to mid 60s.

Much cooler today with low level onshore flow increasing. Stratus along the coast not getting very far inland. Weak low level convergence could produce some cloud cover over the Central Puget Sound this afternoon. Marine air filling up the interior this morning with high temperatures dropping into the 70s for the interior and 60s for the coast.

Little change in the pattern tonight through Wednesday night. Upper level ridge centered well offshore with northwesterly flow aloft. In the lower levels onshore flow will weaken tonight through Wednesday night. Lows in the upper 40s to mid 50s. Highs in the 60s on the coast and upper 60s to mid 70s inland.

Northwesterly flow aloft continuing Thursday with the low level flow going light. This will give the area a little warmer day with highs in the upper 60s to mid 70s coast and 70s and lower 80s inland. Felton

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Upper level ridge remaining well offshore with northwesterly flow aloft through the weekend. Weak system moving by to the north Sunday could produce a shower in the North Cascades. Light low level flow becoming onshore at times. With the lack of offshore flow temperatures will not get too warm. Highs Friday in the mid 70s to lower 80s for the interior cooling to the 78s over the weekend with a little more onshore flow. Highs on the coast in the mid 60s to lower 70s. Upper level ridge building over the area Monday with low level flow going light. High temperatures warming into the mid 70s to mid 80s interior and lower to mid 70s coast. Lows through the period in the 50s.

AVIATION

As the upper level ridge continues to flatten, prevailing west/northwest winds persist. Gusty westerly winds are expected today near the coast as well as in and adjacent to the Strait of Juan de Fuca. Infrared satellite imagery shows an area of stratus located offshore. These clouds are expected to creep closer to the coast and induce a period of MVFR ceilings later this morning. Additional clouds develop this afternoon/evening and could bring a few hours of low-end VFR ceilings to the greater Seattle Metro area.

KSEA...VFR conditions are expected through the TAF period. As onshore flow continues today, a Puget Sound Convergence Zone may briefly materialize this morning and early afternoon, with southwesterly flow at SeaTac from 18-22Z. Scattered to broken ceilings as low as 3000ft could occur as clouds develop this afternoon. After 22Z, northerly flow will dominate into the overnight hours, allowing for clouds to clear out.

MARINE

Onshore flow continues today as the surface thermal trough moves east of the Cascades into eastern Washington. Northwesterly winds will gust to 25kts over the coastal waters, with a Small Craft Advisory in effect from this afternoon through early Thursday morning. Seas will become locally-wind driven and become very steep. Wave heights will increase throughout the day Tuesday up to 10 to 13 ft with a dominant period of around 10 seconds. Waves in the outermost waters may reach up to 15 ft by late week.

A Gale Warning is in effect for the central and eastern waters of the Strait of Juan de Fuca, with gusts up to 40 kts expected today associated with a strong marine push. Small Craft Advisory winds will also funnel down into Admiralty Inlet by this afternoon. Winds ease by late tonight.

FIRE WEATHER

The return of low level onshore flow today will ease fire weather concerns west of the Cascades. Elevated fire weather concerns return on the warmer days, Friday and Monday, during the next week. Minimum relative humidity values dropping to around 30 percent those days along with some breezy conditions in the afternoon and evening hours. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Warning until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 2 PM this afternoon to 11 PM PDT this evening for Admiralty Inlet.

Small Craft Advisory from 11 AM this morning to 5 AM PDT Thursday 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.