897 FXUS66 KPQR 111031 AFDPQR Area Forecast Discussion National Weather Service Portland OR 330 AM PDT Thu Oct 11 2018 .SYNOPSIS...Dry weather will persist through early next week with periods of offshore winds and mostly clear skies. Daytime temperatures will be above normal, while nighttime temperatures remain normal or slightly below normal. && .SHORT TERM...Today through Saturday...As the east Pacific ridge continues to push into the Pacific NW early this morning, surface analyses showed the thermal induced surface trough shifting off the coast. Surface observations show offshore winds have been relatively weak so far, and as a result observations and satellite images indicate valley fog has been forming in the Coast Range, and along the northern part of the coast where winds remained light. Other than the morning valley fog, clear skies and a drying air mass expected today with the subsidence under the ridge and the offshore flow. Models agree on showing a shortwave moving across the top of the ridge late tonight into Fri, temporarily erasing the offshore flow in the north as the surface trough is suppressed south by a surface ridge pushing into western WA. This may allow some fog and marine clouds to spread onto the north coastal areas late tonight into Fri, but otherwise impacts on the weather will likely be minimal. The upper ridge rebuilds again Fri night into Sat, allowing thermal induced trough along the coast to spread north back up the OR and WA coastline. Strengthened offshore gradients will result in increased easterly breezes Sat. By Sat morning, temps above the subsidence inverion which models soundings generally suggest as being between 2500 and 3500 ft, will tend to be mild at night, while wind protected areas at lower elevations will tend to radiate well leading to normal or even a little cooler than normal low temps. .LONG TERM...Saturday night through Wednesday...No changes. Previous discussion follows. A 580+ mb upper level ridge holds over the Pacific NW through next Wednesday continuing dry weather with offshore winds and above normal daytime temperatures. A subsidence inversion will result in warmer overnight temperatures for the foothills and Cascades. Areas below the inversion will have radiation cooling and slightly cooler then normal nighttime temperatures. ~TJ && .AVIATION...Dry northerly flow aloft will maintain mostly clear skies the next 24 hours. Expect localized shallow fog or low stratus along the north coast and in sheltered valleys in the interior through around 16Z, but most areas should remain clear thanks to decent offshore flow. KPDX AND APPROACHES...Mainly VFR the next 24 hours, but cannot rule out a few hours of patchy shallow fog impacting the terminal between between 10Z and 16Z. /64 && .MARINE...High pressure will 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 and will likely bring periods of gusty afternoon and evening winds to 25 kt to the central Oregon waters starting Friday. Seas will remain in the 4 to 6 ft range through early next week and may become choppy at times during the afternoons and evenings over the weekend as the winds increase. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ 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.