textproduct: Seattle/Tacoma

SYNOPSIS

High pressure building overhead and weak offshore flow will maintain mild and dry conditions this weekend. A system to the north will flatten the ridge by the beginning of next week, with near-zonal flow aloft and onshore flow at the surface maintaining seasonable conditions with morning clouds and afternoon sun breaks.

SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/

Most of W WA has seen clear skies for much of the tail end of the morning and the bulk of the early afternoon hours. As such, temperatures in these areas are on track with the forecast...generally in the mid 60s to lower 70s. However, there are still areas where low-level clouds are clinging tenaciously: the shores of the eastern Strait around Port Angeles, the Chehalis valley and the I-5 corridor stretching from Tacoma to Everett. Tacoma has since started to warm quickly, bouncing to 66 in the past hour...while Seattle and Everett continue to report temps in the upper 50s to lower 60s as of 1 PM PDT. Both satellite and a look out the WFO window indicates that these clouds will continue to break up and as such there is still some room for warming today. However, afternoon highs probably going to run 2-4 degrees cooler than forecast.

The current upper level ridge will see its axis shift eastward tonight and over E WA Sunday. Once this happens, any ridging in place overhead will flatten out into zonal flow. This change will help to facilitate a return to onshore flow and as such bringing daytime highs more in line with seasonal normals...generally in the lower to mid 60s for most lowland locations. This could result in high temps Sunday being a degree or two cooler than yesterday in most locations. However, for locations that were clouded over today, Sunday may be either on par with today or perhaps a degree or two warmer. The persistent pattern of morning clouds/afternoon sun however could prove to offset this. Ultimately, sided with the majority and trended the forecast down a degree or two from today, with temps generally in the mid 60s to around 70. Monday sees a touch more cooling with lowland temps now fully confined in the mid to upper 60s. Overnight lows remain generally static, ranging from the upper 40s to lower 50s.

No precip expected in the short term.

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LONG TERM /TUESDAY THROUGH SATURDAY/

Ridging builds over the eastern Pacific slowly Tuesday and into the midweek period, which may allow for daytime highs to rebound a handful of degrees back into the upper 60s to lower 70s by Thursday and overnight lows remaining consistent with what is expected in the short term. The ridge is then forced to retrograde as an upper level low from BC drags a frontal system over the CWA Friday and into Saturday. As this falls into day 6 and 7 territory, no surprise that ensemble members have a wide array of opinions of how well this front holds together and how much potential precip it will bring. Ensemble mean generally leaning toward light precip with PoPs for this time frame generally ranging 20-50 pct. This seems like a reasonable solution for now. The main impact from this system will be to drag temps solidly back into Climo...if not slightly below...as daytime highs will range in the upper 50s to lower 60s by Saturday.

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AVIATION

High pressure and offshore flow across western WA for dry and stable conditions. The flow aloft is west to southwest. Low clouds and fog likely across most lowland areas overnight for IFR to LIFR conditions. Skies clearing 18-21z Sunday with VFR conditions expected in the afternoon and evening. 33

KSEA...VFR this afternoon and evening. N/NE wind 10 kt easing to 5 kt or less after 06z. IFR to LIFR cigs overnight through Sunday morning. VFR expected by 21z Sun. 33

MARINE

Offshore flow through Sunday with a thermal trough along the coast. Low pressure will shift inland Sunday night with a westerly push down the Strait of Juan de Fuca. Another push is forecast Monday night. The flow remains onshore through the end of the week. 33

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM Sunday to 5 AM PDT Monday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.