Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
255 FXUS66 KPQR 161020 AFDPQR Area Forecast Discussion National Weather Service Portland OR 320 AM PDT Sun Aug 16 2026 .SYNOPSIS...Seasonably warm and dry conditions expected through much of the week with morning clouds and afternoon clearing. Winds generally out of the west/northwest, strongest in the afternoon and along the Central Columbia River Gorge and Upper Hood River Valley. Chances for precipitation return at the end of the week, but uncertainty remains with exactly how much precipitation we would receive. && .DISCUSSION...Today through Saturday...Seasonably dry and warm conditions continue through the week with minimal weather impacts. The large-scale pattern remains fairly stagnant through the period, with broad and relatively flat upper-level ridging over the majority of CONUS and a weak, positively-tilted upper- level troughing over the northeast Pacific. This pattern will support continued onshore flow, maintaining near-normal daily high temperatures in the 80s within inland valleys and 60s along the coast, and overnight lows in the 50s across the region. Each morning will be characterized by morning clouds (at least along the coast) which clear up in the afternoon. Expect mostly light winds from the west/northwest across the region this week, strongest each afternoon and along the Central Columbia River Gorge and Upper Hood River Valley. The majority of ensemble members are in agreement that upper- level ridging over the Rockies and Great Basin will build late in the workweek, which would favor a brief warm-up on Thursday. However, ensemble guidance shows the broad upper-level trough over the northeast Pacific progressing toward the Pacific Northwest by Friday into the weekend, resulting in slightly cooler temperatures and winds coming from the west/southwest. Chances for precipitation also increase to 10-30% across the region during this time, however, there is still high uncertainty with how much precipitation we would receive and the exact timing. If the a potential front at the end of the week is too weak, it will have a hard time counteracting the overall dry airmass and make it unlikely for us to receive substantial rainfall. -10/36 && .AVIATION...Through 12z Monday...Satellite imagery and terminal observations as of early Sunday morning depicts a mix of low stratus and high clouds across the region, resulting in high-end MVFR (2-3 kft) and low-end VFR conditions across terminals. High confidence for MVFR CIGs continuing along the coast and northern Willamette Valley through 18-20z Sun, with a 30-50% chance for MVFR CIGs developing at any given hour between 13-16z Sun for the central and southern Willamette Valley. After 18-20z Sun, stratus across the region will begin to dissipate as daytime heating progresses, returning VFR conditions. Chances increase for IFR/MVFR stratus returning to the coast after 06z Mon. Northwesterly winds around 5-10 kt today across the Willamette Valley and 10-15 kt with gusts up to 20 kt along the coast. KPDX AND APPROACHES...MVFR CIGs through 17-18z Sun, then improving to VFR through the rest of the TAF period. Northwesterly winds 3-7 kt, strongest in the afternoon and evening. -10 && .MARINE...A largely stagnant pattern continues through much of the week with high pressure offshore supporting northerly to northwesterly winds of 8-15 kt and gusts up to 20 kt. Friday into the weekend, weak low pressure over the northeast Pacific will shift winds more westerly/southwesterly across the waters, but chances for small craft wind gusts exceeding 21 kt remain 5-10%. Benign seas of 3-6 ft persist through the period. -10/36 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland