Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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120 FXUS66 KSEW 302249 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 345 PM PDT Mon Jun 30 2025 .SYNOPSIS...High pressure aloft will maintain warm and dry conditions across the region early this week. As the high pressure weakens toward midweek, expect a return to near normal temperatures. Most areas remain dry through the week, though a few showers are possible near the coast and mountains by the end of the weekend. && .SHORT TERM /TONIGHT THROUGH THURSDAY/...
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Clear skies over W WA this afternoon as upper level ridging remains the dominant weather influence over the region. Temps as of 3 PM running the range from lower to mid 70s for water adjacent locations while some obs on the islands are still down in the mid to upper 60s. Interior locations are feeling the heat though with most land-based obs in the mid to upper 80s. With the ridge axis moving further east, centering over ID Tuesday, W WA will be on the backside of the feature and as such, will see temps start to cool but temps will start to cool, albeit gradually. An approaching upper level trough will help to enhance onshore pushes, which will help take the edge of temps more significantly Wednesday and Thursday, with daytime highs generally in the lower to mid 70s for the interior and mid to upper 60s for coastal and water- adjacent locations. This pairing of the upper level trough and onshore flow will allow for some moisture to increase over the area, mainly in the form of some clouds...but no precip is expected for much of W WA. Some isolated showers may be possible over portions of the Cascades Wednesday and Thursday with a shortwave disturbance, but otherwise this feature should have minimal impact. 18
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...Confidence in the specifics of the pattern late in the week, including the Independence Day holiday, remains rather low with ensemble guidance continuing to exhibit a rather large spread in how the pattern may evolve. The forecast continues to reflect the most likely scenario of a generally zonal flow pattern that will provide for some morning clouds and temperatures close to (or slightly above) seasonal normals. This would leave the door open to perhaps a few light showers near the northern coast and in the North Cascades over the weekend, but even in these favored locations the chance of rain remains quite low (less than 20 percent) for the weekend. 12 && .AVIATION...
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The air mass is dry and stable across western WA with broad ridging over the Pac NW. Low level stratus clouds will push inland tonight, through the Chehalis gap and strait, for MVFR to IFR conditions. Expect VFR conditions in the interior. 33 KSEA...VFR tonight and Tuesday with N winds to 10 kt. 33
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&& .MARINE...
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A thermal trough along the coast will lead to gusty winds and choppy seas over the coastal waters - a Small Craft Advisory remains in effect. Expect strong westerly pushes down the Strait of Juan de Fuca tonight, Tuesday night and Wednesday night. Gales are possible in the strait Tuesday night. A weak front will cross the waters on Wednesday, with onshore flow following through the end of the week. 33
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&& .FIRE WEATHER...
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Warm and dry conditions will continue across the region through Wednesday under high pressure. Daytime RH values will continue to dip to around 30-35% across the Cascades, and central Puget Sound southward. A few spots in these areas may see RH drop to 25%, with elevated fire weather concerns (particularly in dry grassy areas). Light winds out of the north to northeast is expected with a slight breeze in the afternoons. Tuesday morning will have a modest RH recovery overnight/morning. As a deeper marine push begins to tap in some marine air west of Puget Sound Wednesday, a few areas east of the sound may still stay drier, with recoveries improving more on Thursday. Model guidance has the onshore flow with cooler temperatures and higher RH`s continuing through the holiday weekend. The biggest uncertainty will be if any showers are able to develop with weak troughs pushing through. HPR
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&& .SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None. PZ...Small Craft Advisory until 5 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from Tuesday afternoon through late Tuesday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 5 AM PDT Tuesday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.
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&& $$