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Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
016 FXUS66 KSEW 132119 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 219 PM PDT Sat Jul 13 2024 .SYNOPSIS...An upper level ridge remains over Western Washington through the weekend into next week with continued low level onshore flow. This will maintain above normal temperatures, with only subtle variations in the strength of the marine pushes each night. && .SHORT TERM /TONIGHT THROUGH TUESDAY/...Zonal flow will remain in place today as a flat upper level ridge remains parked over western Washington. Lingering marine stratus over coastal locations will dissipate by this afternoon, joining the rest of the area in clear skies. Interior locations will have temperatures warm into the mid 80s, while coastal locations will see highs ranging from the mid 60s to the lower 70s. Temperatures will continue to remain above normal through the interior through the short term, while this persistent pattern of light onshore flow will continue through the first half of next week. Zonal flow and the aforementioned weak upper ridge will shift eastward on Tuesday, opening the way for a longwave trough to nudge closer to the region. .LONG TERM /WEDNESDAY THROUGH SATURDAY/...As the ridge shifts eastward into Wednesday, a longwave trough offshore will introduce a dry south/southwesterly flow throughout the area. This may open the door to increased convection chances in the Cascades as a weak front attempts to cross over the region. Ensemble guidance showing low probabilities at this time, but it is something to monitor over the next couple of days. As of now, the most likely outcome would be continued warm and dry conditions, but some light precipitation may be possible during this time frame (Cascade focused). An upper level ridge to the east looks to intensify through the remaining of the long term period, with temperatures still staying above average, in the mid to upper 80s. Mazurkiewicz && .AVIATION...Mostly VFR. Another marine push with onshore flow will cause localized IFR/LIFR along the coast late tonight into Sunday morning. Forecast models continue to show the marine stratus layer expanding inland through the early morning, though KOLM is favored to stay VFR with the stratus holding to the west. Stratus will slowly evaporate by 19z Sun with KHQM once again seeing VFR conditions Sun afternoon. Winds generally N-NW 5 to 10 kt this afternoon, decreasing overnight and shifting to W-SW by Sunday afternoon. KSEA...VFR under clear skies. Light north to northwest winds 5 to 10 kt this afternoon, decreasing overnight and shifting S-SW by 12z Sunday morning. Low chance (20% probability) of a strong enough marine push for MVFR ceilings overnight Sunday into Monday morning, but confidence is low. 15 && .MARINE...Little change in the weather pattern with high pressure situated offshore and a thermal trough over eastern Washington. A Small Craft Advisory continues through today over the outermost coastal waters for gusty northwesterly winds up to 25 kt, with the highest speeds concentrated farther than 30-40 NM offshore. Diurnally driven pushes of westerly winds down the Strait of Juan de Fuca will occasionally be strong enough to warrant additional headlines into next week, with the next strongest push expected to be Sunday evening. Seas 6 to 8 ft across the coastal waters will decrease Sunday night into Monday to around 4 to 6 ft through the beginning of next week. 15 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 11 PM PDT this evening 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 Point Grenville To Cape Shoalwater 10 To 60 Nm. && $$