textproduct: Seattle/Tacoma

SYNOPSIS

Upper level low well south of the area will make its way into the Plains Saturday while an upper level trough remains offshore. Onshore flow in the lower levels. The trough will move inland Saturday night. Upper level ridge building over Western Washington Sunday will remain over the area through Tuesday. A weakening front will move through Wednesday.

SHORT TERM /TODAY THROUGH SUNDAY/

No major changes to the short/long term sections this morning. -HPR

Middle and high level clouds associated with the convection have spread over parts of Western Washington. In the lower levels a marine push in progress with stratus already into the Central Puget Sound at 3 am/10z. Doppler radar has convergence zone showers over Snohomish and King county. Temperatures were in the 50s.

Little change in the pattern the next couple of days with an upper level trough offshore and varying degrees of low level onshore flow. Convergence zone moving very little this morning before dissipating this afternoon. Middle level clouds moving out of the area later today but with the onshore flow remaining intact skies will be at least mostly cloudy this afternoon after a cloudy morning. Little change in the temperature today with highs near 60.

Another surge of westerlies through the Strait of Juan de Fuca tonight could re-energize the convergence zone over the Central Puget Sound. Mostly cloudy to cloudy skies outside the convergence zone. Lows tonight in the 40s.

Marine layer over the area Saturday will retreat back to the coastline in the afternoon as low level onshore flow begins to weaken. Temperatures slightly warmer with highs in the upper 50s to mid 60s.

Weak upper level trough offshore moving inland Saturday night will have little in the way of moisture associated with it. Onshore gradients continuing to weaken Saturday night and by Sunday the low level flow goes light. Upper level ridge beginning to build over the area Sunday. This along with the weakening onshore flow will minimize the marine layer Saturday night into Sunday morning resulting in a sunny day Sunday. Highs getting back to near normal, 60s and lower 70s. A little on the cool side Sunday morning with the colder locations getting into the upper 30s. Lows elsewhere in the 40s.

Seattle-Tacoma airport has recorded 0.02 inches of rain this morning. This is the 63rd day with measurable rain so far this year. If there is no more rain days this month this will tie for the 5th lowest number of rain days in the first five months of the year since records started at the airport in 1945. Have to go back to 1985 to find a year with a lower number of rain days ( 56 days ) in January through May. The normal number of rain days for January through May in Seattle is 78 days, record low 54 days in 1949, record high 98 days in 1961. Felton

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Extended models in good agreement with the upper level ridge remaining over Western Washington through Tuesday. Low level flow turning offshore Monday night into Tuesday making Tuesday possibly the warmest day of the year. The heat is short lived. Surface ridge out ahead of the next weather system moving into the coastal waters Tuesday night. Rapidly increasing onshore flow and the resulting marine push will bring clouds and cooler temperatures back to the area. What is left of the front moving through Wednesday. Zonal flow aloft with low level onshore flow Thursday.

Highs Monday in the 70s and lower 80s warming to the 80s and lower 90s Tuesday. Moderate HeatRisk Tuesday. Highs cooling into the 60s and lower 70s Wednesday with mid 60s to mid 70s Thursday. Lows in the 40s Sunday night, mid 40s to mid 50s Monday night through Wednesday night. Not expecting any records to be broken Tuesday.

AVIATION

Southwest flow aloft will develop today with a broad upper level trough over the Gulf of Alaska. Onshore flow continues in the low levels. Showers continue across the area, with convergence showers across the Sound and a band of showers currently moving east of the Sound. Current conditions at the area terminals are a mix of IFR to MVFR across the interior in shower activity and VFR outside of the shower activity. A gradual lifting of ceilings is expected this afternoon, but areas of MVFR may linger around any remaining convergence zone activity. Most areas should improve to VFR by early evening.

KSEA...MVFR ceilings with scattered showers are expected to continue into the terminal through midday. Ceilings are then expected to gradually lift with shower activity diminishing. VFR is expected after around 22Z. Surface winds S/SW 7-12 knots this morning will become NE at 8-12 kt by this afternoon, around 22Z.

27/14

MARINE

Strong onshore flow will persist today with gales expected along the Strait of Juan de Fuca. Winds will remain between 15-25 kt across the coastal waters before easing late tonight. Seas will hover between 10-16 ft throughout the day, before subsiding to 7-9 ft late tonight into Saturday. Onshore flow will ease over the weekend allowing for winds and seas to continue to ease and subside. Weak offshore flow will develop early next week with a thermal trough forming near the coast.

27/14

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 11 PM PDT this evening for Admiralty Inlet-Grays Harbor Bar-Northern Inland Waters Including The San Juan Islands.

Small Craft Advisory until 3 AM PDT Saturday for 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-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 5 AM PDT Saturday 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.