textproduct: Seattle/Tacoma

SYNOPSIS

Mostly dry and mild conditions will continue through much of next week across western Washington as an upper level ridge remains situated over the region. Troughing is on track to return by next weekend, bringing cooler conditions and increased chances for mountain showers.

SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/

Northerly flow aloft has brought another dry day across western Washington, with temperatures on track to peak several degrees above normal in the upper 60s to lower 70s. High pressure will continue to build onshore tonight into Monday, generating onshore flow that will allow low clouds to develop along the coast and filter inland towards the Puget Sound Monday morning. The onshore flow will bring in cloudy skies across western Washington, limiting temperatures into the upper 50s to lower 60s. This system will also bring a slight chance of light showers along the coast and over the mountains. More of the same will continue on Tuesday, with a degree or two of cooling under mostly cloudy skies.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

An upper level ridge building offshore will drift closer to the Washington coastline on Wednesday and Thursday, bringing in a warming trend with clearing skies. The ridge axis will shift inland on Thursday, bringing the warmest temperatures of the week. Highs will peak in the upper 60s to mid 70s across the lowlands, resulting in areas of Minor (Yellow) HeatRisk east and south of the Puget Sound.

Models have come into slightly better agreement heading into next weekend, showing split flow developing aloft as a closed low drops southward along the coast and the upper level ridge progresses east of the Rockies. This will likely maintain mild temperatures across the region, with ensembles maintaining a slight chance of mountain showers next weekend.

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AVIATION

A ridge will remain offshore with troughing to the east over the north Great Plains, keeping the flow north/northeasterly, with a break in the flow Monday as a trough passes offshore. VFR will continue this afternoon with winds beginning to solidify to the north at 5-10 kt. Onshore flow picks up tonight into Monday. This increases the likelihood of MVFR for most interior terminals (and a higher likelihood of IFR/LIFR along the coast). These ceilings are expected to linger into much of Monday before receding back towards the coast in the afternoon/evening. Winds will return to the south at the surface late tonight (around 5 kt) and into Monday (5-10 kt).

KSEA...VFR through the evening, then a 60% chance of MVFR between 12Z and 18Z. There is a 30% chance that the ceilings briefly drop to IFR during this period from the marine push. Conditions will become VFR late Monday afternoon. Winds: North 5-10 kt through the evening, becoming south 5 kt overnight, and southwest 5-10 kt Monday.

HPR

MARINE

High pressure continues over the coastal waters, with lower pressure to the east. The flow returns to onshore this week with weak pushes through the Strait of Juan de Fuca. The strongest push in the guidance is Monday evening, but the probability of winds exceeding 20 kt remains low. 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 6-8 ft for the remainder of the week. There is potential for 9-10 ft seas Thursday and Friday depending on the track of the next system.

HPR

HYDROLOGY

No river flooding is expected over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.