272 FXUS66 KPQR 202208 AFDPQR Area Forecast Discussion National Weather Service Portland OR 304 PM PDT Fri Jul 20 2018 .SYNOPSIS...Hot weather return to the interior starting Sunday through early next week. The warm weather will likely continue through the week. && .SHORT TERM...Tonight through Monday. Seasonal temperatures will be with us one more day. Then a warm-up follows early next week with temperatures well above normal. Skies will be clear this evening with clouds returning to the coast overnight as a field of marine stratus well offshore moves to the coast. A shortwave trough arrives early Saturday morning that could extract some drizzle out of the marine stratus. SREF, NAM-nest shows 20-30 percent PoPs so have added drizzle to the north coast zones for early Sat morning. By Sunday morning the upper trough has moved on allowing a strong upper ridge over the Desert Southwest to expand into the region. Below about 700 mb, high pressure builds into eastern OR/WA resulting in east to northeast flow across the CWA. If there is significant smoke from fires east of the Cascades, it could advect into our area. The upper ridge strengthens on Monday and should be the hottest day this week with inland highs in the upper 90s. The coast will be cooler with highs in the 70s. .LONG TERM...Monday night through Friday...Dry weather and much above normal temperatures will remain with us. Monday looks to be the hottest day inland which will set up for a warm night for the interior lowlands with the warmest spots in urban areas. Not a whole lot of change for the remainder of the long term. Global models are in good agreement through Tue where the region will remain under the influence of the strong upper high centered over the Desert Southwest. The GFS and a majority of its ensemble members depress the ridge slightly as a shortwave trough moves into the region Wed-Thu. It is not much of a trough though, 500 mb heights remain above 585 DAM. The ECMWF however is weaker with this feature. This means the GFS would bring slight cooling with onshore flow, while the ECMWF would maintain the very warm conditions inland. Coastal areas remain cooler with light onshore flow. The GFS shows some moisture and instability nearing the SE portion of the forecast area Tue. The ECMWF does not. Will have to see how later model runs handle this feature. /mh && .AVIATION...Weak onshore flow over the northern half of the forecast area will bring predominately MVFR conditions to KAST later this evening and mostly VFR conditions to the Portland Metro TAF sites for the next 24 hours. There could be a few hours of MVFR cigs Sat morning for metro sites, but confidence is low. Dry northerly flow over the southern half of the will result in mostly VFR conditions for the remaining TAF sites. The exception to this may be KONP which could see a few hours of lower cigs early Sat morning, but suspect winds will remain slightly offshore and prevent lower cigs from developing. KPDX AND APPROACHES...Mostly VFR the next 24 hours. There could be a few hours of MVFR cigs Sat morning, but confidence is low. /64 && .MARINE...High pressure over the northeast Pacific and thermal low pressure over southwestern Oregon will result in a fairly typical summer-time northerly wind pattern. The surface ridge axis is a bit further north today which could bring a few stronger gusts to 25 kt for areas south of Cape Meares this afternoon and evening, but probably not enough to warrant an advisory. Otherwise, wind gusts near 25 kt should be fairly widespread across the central Oregon waters each afternoon and evening through Saturday. Seas will continue to flirt with steep and hazardous criteria as combined seas climb into the 6 to 8 ft range with dominant periods between 7 to 8 seconds. Still think the best chance of widespread square seas have passed so will not reissue an advisory for it. Nonetheless, seas will remain very step. Winds and seas should ease a bit Sunday through Tuesday as thermal low pressure over southern Oregon shifts north and inland. A return to a stronger northerly wind pattern looks to arrive towards the middle of next week. /64 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for winds until 3 AM PDT Saturday for Coastal Waters from Cascade Head OR to Florence OR out 60 NM. && $$ 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.
Return to Home page