textproduct: Seattle/Tacoma

UPDATE

An odd mix of clear skies/high clouds over much of western Washington this evening while patches of low stratus linger over portions of the coast, all of the south Sound and some spots north of Seattle. Continued offshore flow may be enough to offset any further stratus or fog development, but this will need to be monitored overnight. Inherited forecast on track.

SYNOPSIS

A strong and stable ridge will remain in place throughout the rest of the week and into early next week. Periods of stratus and patchy fog will occur through then. East to northeast flow will strengthen into Friday, helping to erode some of the stratus that has been around for the last several days.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

The ridge will remain in place throughout the short term. A passing disturbance to the east will kick up the ENE winds overnight into Friday morning, but will remain below any sort of advisory thresholds. Gusts between 15 to 20 mph will be possible by Friday morning. Given the warmer and drier nature of these winds, it will help to keep most of the stratus out of eastern Puget Sound, though indications as of now are that patches of stratus and fog may still linger through Olympia and as far north as Tacoma into Friday morning.

The ridge will shift slightly more overhead over the weekend, favoring clearer skies and less of a stratus intrusion. With that, temperatures will be somewhat cooler, with highs in the low 50s and lows dipping into the mid 30s.

LONG TERM /SUNDAY THROUGH THURSDAY/

The extended forecast also remains largely dry and still influenced by the ridge pattern. Winds look to remain light and at times, offshore. Some light QPF is finally in the grids on Thursday of next week, but even now, that comes with little certainty.

21

AVIATION

An upper level ridge pattern will remain in place through Friday with light N/NE flow. MVFR conditions persist over the south Sound while generally VFR elsewhere given generally clear skies. Majority of obs sites still showing offshore low-level flow, and cannot help but wonder if that may be enough to offset any further fog or stratus development. However, both the lingering stratus already mentioned as well as other isolated patches of MVFR to IFR conditions do keep the fog threat in place. Current TAFs geared more toward stratus development and given the pattern of the past few overnight/early morning periods, feel that may be the best way to go unless conditions continue to improve toward the 06Z issuance. Then may need to factor in this reality. Helping to maintain persistence forecasting though is that model data continues to advertise fog and low vis. So again, may not deviate too much, if at all, from inherited forecast.

KSEA...VFR conditions in place, but with stratus lingering to both the north and south of the terminal...cannot help but wonder if skies will fill in. This is the main forecast issue overnight. Probability for fog Friday morning remains at 20-30%, but is is conditional on cloud coverage, if any, and winds easing enough by Friday morning for formation. At the time of this writing, winds remain up around 8-12 kts and models do not really bring them down until 24 hours from now. Forecast has lower levels filling in, resulting in MVFR to IFR conditions developing overnight before clearing once more Friday afternoon.

18/HPR

MARINE

High pressure offshore remains with a thermal trough along the coast keeping the flow offshore. Breezy east wind gusts up to 25 kt will be possible in the west/central Strait of Juan de Fuca and the northern inner coastal zones (where a small craft advisory continues). Few gusts to 20 kt are possible in the waters off of Ocean Shores. Otherwise, no significant winds are expected after Friday through Wednesday. Seas will remain at 4-6 ft today through Wednesday.

HPR

HYDROLOGY

No river flooding is expected over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 10 AM PST Friday for Central U.S. Waters Strait Of Juan De Fuca-West Entrance U.S. Waters Strait Of Juan De Fuca.