textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge along British Columbia coast with low level onshore flow through Tuesday giving Western Washington mostly cloudy and cooler weather. Upper level ridge moves over the area Wednesday then slides east Thursday. Weak upper level trough moving through Thursday night. Upper level ridge building to the northwest with an upper level low developing well west of California Friday through the weekend with temperatures warming into Sunday.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Marine push ongoing this morning. Stratus will continue to fill in over the Central Puget Sound through sunrise with the stratus getting as far north as Skagit county. No top reports yet this morning but the Black Hills in Southwest Washington are covered so tops at least 3000 feet and probably a little higher. Continuing onshore flow through the day combined with the thickness of the marine layer will keep skies cloudy this morning before somewhat of an afternoon breakout over the interior. Skies remaining cloudy along the coast with light showers or drizzle possible this morning. Cooler today with highs in the mid 50s to lower 60s.

Little change in the pattern tonight into Tuesday with low level onshore flow. Marine layer returning to the interior overnight for another cloudy start to the day. Low level flow going light in the afternoon but cross Cascade gradients still around plus 6 mb late in the afternoon. This will make it hard for a complete clear out of the stratus over the interior. Will word the forecast mostly cloudy. Highs again in the mid 50s to lower 60s. Lows Tuesday morning in the 40s.

Upper level ridge along the British Columbia coast today into Tuesday morning moving over Western Washington Tuesday night into Wednesday. Low level flow going light northerly Wednesday with cross Cascade gradient trending towards zero. This will thin out the marine layer. Plenty of sunshine Wednesday with highs back into the lower to mid 60s. Lows Wednesday morning in the mid 30s to mid 40s. Felton

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Upper level ridge over the area Wednesday night moving east Thursday. Weak upper level trough sliding through Thursday night with another upper level ridge rebuilding Friday. Models continuing to have trouble latching on to a solution for Friday night through the weekend. Latest solution has an upper level block forming offshore over the weekend with north northeasterly flow aloft and the low level flow turning offshore.

Highs Thursday in the 60s and lower 70s, cooling a little Friday into the 60s then warming over the weekend to the mid 60s to mid and upper 70s by Sunday. Current model blend has a high of 74 for Seattle Sunday. About a quarter of the solutions have the high in the upper 70s. Normally in May a high in the upper 70s would not be a record in Seattle. 30 out of the 31 days in May have a record high of 82 degrees or warmer. The one day that does not, May 3rd with a record high of 77. Outside chance of setting a record Sunday. The average first 80 degree plus day in Seattle is May 20th. The earliest April 1st, 1987 ( 82 degrees ) and the latest July 21, 1980 ( 85 degrees. Something happened in 1980 that caused this late date ). Felton

AVIATION

North to northwesterly flow aloft continues through the TAF period with troughing over the interior West and upper ridge offshore. Onshore flow this morning is resulting in stratus spreading into the interior. Widespread MVFR cigs continue this morning. Cigs will slowly improve into VFR around 20-22z Monday afternoon for interior locations, with MVFR continuing along the coast. More widespread MVFR cigs are in the forecast overnight after 11-12z. Southerly winds 8-12 kt with gusts around 20 kt for interior terminals.

KSEA...MVFR cigs at the terminal this morning. Improvement to VFR expected this afternoon after 20z. S/SW surface winds through the TAF period ranging between 8 to 12 kts with gusts near 20 kt possible this morning and during the afternoon. More MVFR cigs likely to develop overnight after 14-16z.

41/29

MARINE

High pressure continues over the coastal waters, with lower pressure inland. Onshore this week with weak pushes through the Strait of Juan de Fuca. A Small Craft Advisory continues for the Northern Inland waters for this morning. Small craft winds have subsided for the Central and East Strait of Juan de Fuca this morning and the advisory has been allowed to expire. An additional push in the guidance looks to occur on Monday evening, but the probability of winds exceeding 20 kt remains low at this time. Low ceilings in the coastal waters Monday morning (with pockets of fog) may lower visibilities at times to mariners. The next potential system may bring breezy winds over the coastal waters around Friday.

Seas for Sunday hold around 4-6 ft, and increase to 6-9 ft for the remainder of the week.

41/29

HYDROLOGY

No river flooding in the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 9 AM PDT 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 noon PDT today for Northern Inland Waters Including The San Juan Islands.