Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
541 FXUS66 KSEW 092229 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 329 PM PDT Sun Jun 9 2024 .SYNOPSIS...Brief upper-ridging will rebound on Monday but only to be replaced by weak troughing and shower activity on Tuesday. Mostly zonal flow aloft afterwards with near-normal temperatures however, cooler and wetter weather looks to return by the weekend. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/...As mentioned, a transient ridge looks to build into the region tonight as upper- troughing shifts into the Inland Northwest. Mostly dry conditions are expected but onshore flow looks to strengthen. With that, widespread marine stratus is expected to develop across W WA overnight into early Monday. Low temperatures are to range mid 40s to lower 50s around seasonal after a day of above average temperatures. Dry conditions are favorable for Monday with weak ridging in the 500 mb levels but upper-troughing will return Monday night into Tuesday along with shower chances. Areas with the best chance for wet weather are favored mostly along the coast, northern interior and higher elevations. Temperatures are expected to cool also, as forecast highs on Monday of low to mid 70s across the interior will fall to the mid to upper 60s on Tuesday. Low temperatures are to be in the mid 40s to lower 50s for both nights. We`ll see zonal flow aloft on Wednesday throughout the region. Any lingering showers are expected to dry out but marine stratus will remain during the morning before burning off by the afternoon. Pleasant conditions are in the offing with seasonal temperatures. .LONG TERM /THURSDAY THROUGH SUNDAY/...Guidance is keying in on weak ridging returning on Thursday with a slight bump up in temperatures. But, a trough will swing out of the Gulf of Alaska and into the region on Friday and influence conditions into the weekend. Here we`ll see another period of below-normal temperatures and chances for showers across the region. McMillian && .AVIATION...A weak upper level trough will continue to exit the region, moving into eastern Washington tonight. Zonal flow will then persist tonight into Monday. Radar showing a few light showers over the northern portions of the Cascades this afternoon, but overall thunder threat looks to remain mostly east of the Cascade crest. Satellite still showing stratus retreating, but persisting along the coast this afternoon. Conditions for the majority of the interior terminals have rebounded to VFR, however MVFR ceilings remain for terminals in stratus. Increasing low level onshore flow tonight will yield another round of stratus pushing into the interior by early Monday morning (most likely between 09-12Z for interior terminals). Extent of stratus looks to be more widespread than this morning and will likely result in a few hours of MVFR to IFR conditions. A rebound to VFR for majority of terminals likely by 18Z as stratus scatters. KSEA...VFR today with S/SW winds 5-10kt. Low clouds and MVFR conditions, along with light/variable wind, overnight toward 12Z Mon. 14 && .MARINE...High pressure will remain situated over the northeastern Pacific through Monday for periods of northerly winds over the coast and westerlies through the Strait of Juan de Fuca. Another strong push of westerlies is expected down the strait tonight- where a Gale Warning remains in effect. Meanwhile, have issued a small craft advisory through this evening for seas across the coastal waters hovering around 10 ft. Seas will gradually continue to subside tonight and back towards 4-6 ft again on Monday. A frontal system will then move across the area waters on Tuesday. Seas look to increase back towards 10-12 ft over the coastal waters on Tuesday. High pressure will then build back into the region in the wake of the front Tuesday night into Wednesday. Another front looks to traverse the area waters late in the week. 14 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 8 PM PDT this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 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-Grays Harbor Bar. Gale Warning until 5 AM PDT Monday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$