textproduct: Seattle/Tacoma

SYNOPSIS

An upper level ridge will remain over western Washington through Thursday, keeping temperatures above normal. Onshore flow will continue throughout the week, bringing rounds of morning stratus to the area. A dissipating frontal system will move into the region Friday into Saturday, bringing the next chance of some showers. Another ridge will build into the region Saturday afternoon into Sunday, but looks to weaken early next week.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

Persistent clouds have been in place across much of the lowlands into the afternoon with the persistent onshore flow. This has been responsible for keeping skies a bit cloudier and temperatures a bit cooler. Still expecting some breakout inland late this afternoon, but the coast is unlikely to see any improvement.

An upper level ridge will remain over western Washington through Thursday, keeping temperatures above normal. Onshore flow will continue throughout the week, bringing rounds of morning stratus to the area. A dissipating frontal system will move into the region Friday into Saturday, bringing the next chance of some showers. Another ridge will build into the region Saturday afternoon into Sunday, but looks to weaken early next week.

LONG TERM /FRIDAY THROUGH TUESDAY/

The pattern shifts a little bit late Friday as a weakening frontal system moves into the region. While this will bring back a small chance of some light showers across the region, the most likely scenario remains that many areas will remain dry. The latest ensemble guidance has remained consistent in suggesting less than a ten percent chance of more than a tenth of an inch of rain with this system. As such, the more notable impact to sensible weather would be increasing cloud cover and a slight cool down in temperatures. Expect temperatures to only reach into the 60s Friday.

High pressure will then build back into the Pacific Northwest in the wake of the front for another period of dry weather heading into early next week. Temperatures will warm a few degrees each day, topping out in the mid 70s for highs by Sunday. Minor HeatRisk will return to areas across the interior, though the coast will remain cooler, with temperatures only expected to be in the 60s.

AVIATION

Widespread stratus clouds have been firmly entrenched in the region throughout much of the day today, only now slowly retreating from the KBLI area. Some thinning seems to be occurring according to satellite imagery throughout the rest of Puget Sound. Interior TAF sites may not see more appreciable clearing until after 22Z. High pressure remains in place with continued onshore flow through the valid TAF period. Expect breezier westerly winds through the Strait of Juan de Fuca, otherwise southwesterly surface flow will continue at 5-8 kts.

KSEA...Stratus remains in place over the terminal this afternoon, with little confidence in significant clearing before 22Z. Clouds becoming scattered to broken thereafter. Onshore flow continues overnight, with another round of stratus likely to come back in early tomorrow morning. Surface winds from the SSW at 5-8 kts.

21

MARINE

High pressure remains offshore for the next few days, with onshore flow continuing for the next few days. The Small Craft Advisory for the central and eastern Strait remains in effect for tonight with the strongest winds likely in the central Strait and nearest to the international boundary. Have maintained the gale watch for Wednesday night as the onshore flow could be enhanced by a disturbance passing by the region to the north. However, latest ensemble guidance suggests less than a 30-40% chance of gales across the U.S. portions of the Strait with winds up to around 30 kt. Will await an upgrade of this watch for now given this lower probability. Meanwhile, gusty winds will bring increasing seas over the coastal waters later this week. Initially building into the 5 to 8 ft range, these will be driven by local winds and may reach steepness criteria. Thereafter, expect seas to peak over the outer coastal waters early Thursday around 10 ft.

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 3 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Watch from Wednesday afternoon through late Wednesday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.