895 FXUS66 KPQR 101615 AAA AFDPQR Area Forecast Discussion National Weather Service Portland OR 914 AM PDT Wed Oct 10 2018 Aviation discussion updated. .SYNOPSIS...An extended dry period is in the works for the coming week as ridge of high pressure off the east Pacific moves in over the Pacific NW today, and lingers into early next week. Daytime temps will warm above normal with plenty of sun, while nightime temps remain normal or a little cooler than normal most nights. && .SHORT TERM...Today through Friday...Satellite showed some lower level clouds, below about 7K ft, lingering over the Cascades and the far north OR Coast Range early this morning. Surface analysis this morning showed a thermal induced trough along the south Oregon coast. Models all indicate this trough to develop north up the coast today before shifting offshore tonight. The resulting offshore flow will dry the lower levels, which coupled with subsidence under the ridge pushing in off the Pacific will lead to mostly clear skies for the next few days. With already small dew point depressions, the moist ground and light winds this morning suggest the potential for some fog development, although high clouds are likely to limit any widespread development. Wed night and Thu morning drying from the the offshore flow is likely to severely limit any fog potential, with the wind sheltered lower Columbia valley the most likely to see some fog. As the almost east-to-west oriented upper ridge axis sinks south into Oregon Thu night and Fri, the suface trough pushes inland, at least over the northern parts of the forecast area. Resulting weak nshore flow suggest some potential for coastal fog Fri morning. Some models suggest some marine clouds may spread down the WA coast by fri afternoon before the flow turns more offshore again Fri night. As the Pacific rdge pushes inland during the coming days, and subsidence increases, expect to see daytime temps warm above normal. Below the developing subsidence inversion, which model soundings paint between about 1500 to 2500 ft, wind protected valleys should continue to radiate well keeping nightime lows cool. Above the inversion, Cascade foothills and Coast Range expected to remain a little warmer over the next few nights. .LONG TERM...Friday night through Tuesday...The 12z GFS and 12z ECWMF remain in good agreement. A massive upper level ridge will be the dominating feature. As the weekend approaches the ridge axis looks to tilt slightly positive. As a result a surface high over the Columbia River basin develops, and a surface low looks to develop in the Willamette Valley. This will cause a tightening of the surface pressure gradient along the Cascades, and will cause an offshore flow pattern develop. This tightening of the pressure gradient looks to lead to the most significant east winds so far this season. Gusts up to 35 to 45 mph near, and in the western Gorge are possible from Saturday through early Monday. Expect the the strongest winds to start on Saturday and continue through Sunday evening. During this time period the entire area will stay dry, along with temperatures around seasonal to slightly warmer than seasonal. Highs in the upper 60s to mid 70s, and lows in the mid to upper 40s in the upper Willamette Valley. Along the Cascades and portions of the southern Willamette Valley could see low temperatures in the lower to mid 30s. This overall pattern is expected through Tuesday. /42 && .AVIATION...Mostly IFR inland and VFR at the coast this morning. Expect inland areas to improve to VFR between 19Z and 21Z. Stratus and/or fog are less likely Thursday morning as offshore flow should be a little bit stronger, so expect VFR to last through the end of the forecast period once sites improve today. KPDX AND APPROACHES...Conditions should improve to VFR between 19Z and 20Z. Then expect VFR through Thursday with offshore flow developing on east approaches. Bowen && .MARINE...High pressure will build across the waters today and linger through early next week. This will result in a summer-like northerly wind pattern. Thermal low pressure will build over the southern Oregon coast later this week and could bring periods of gusty afternoon and evening winds to 25 kt to the central Oregon waters. Seas are currently around 9 ft this morning and will continue to subside today. Seas will generally remain in the 4 to 6 ft range through early next week. /64 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for Rough Columbia River Bar from 5 PM this afternoon to 8 PM PDT this evening. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the CWA or forecast area.