Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
257 FXUS66 KPQR 281032 AFDPQR Area Forecast Discussion National Weather Service Portland OR 332 AM PDT Fri Jun 28 2024 .SYNOPSIS...Warm and dry conditions return today, with temperatures warming into the upper 70s and low 80s for interior valleys and upper 60s along the coast. Another shortwave trough returns Saturday night into Sunday, bringing a 15-25% chance of showers, mainly for the coast and higher terrain. Consistently warm and dry conditions continue through next week. Temperatures begin to rise Thursday, but uncertainty remains with how warm we will get. && .SHORT TERM...Friday through Sunday...Dry weather has returned to NW Oregon and SW Washington as fairly zonal upper level flow takes shape over the region into tomorrow. Winds aloft and at the surface have shifted northerly and will remain in this light offshore pattern today. Daytime temperatures will warm nearly 10 degrees inland from yesterday`s temperatures under sunny skies and with the warming north winds. Expect 60s along the coast and upper 70s to low 80s across the inland valleys. NBM indicates a 60-70% probability of temperatures exceeding 80 degrees for the Willamette Valley and a 15-30% for reaching 85 degrees. Saturday remains warm with temperatures rising a couple degrees. NBM probabilities for exceeding 80 degrees and 85 degrees in the Willamette Valley increase to 70-80% and 35-50% respectively. Temperatures along the coast will remain fairly steady in the 60s as winds will turn more westerly from a broad trough deepening into the eastern Pacific and approaching the region. Clouds will begin spreading over the region through the day, which could potentially keep temperatures from rising as much as expected depending on how thick the cloud cover is. The upper trough moves inland Sunday, though ensemble guidance continues weakening the forcing and shower chances. Latest guidance indicates only a 10-25% chance of showers for the northern Cascades and Coast Range due to orographic forcing, though some drizzle is possible along the coast. Any accumulation will be very limited. Temperatures will fall a few degrees back to near normal with upper 70s in the inland valleys and upper 50s to 60s along the coast. -HEC .LONG TERM...Monday through Friday...As the trough passes to the east on Monday, WPC clusters are in very good agreement of upper ridging building over the Eastern Pacific Monday into Wednesday with mostly zonal flow continuing over the PacNW. This is expected to keep temperatures pretty steady with 60s along the coast and upper 70s to low 80s inland. Beyond Wednesday, uncertainty remains on whether the ridging will spread east inland or remain out over the ocean. Nearly all clusters show the ridging moving east at some point into Friday, but strength of the ridge as well as timing varies drastically. As such, NBM high temperature spreads for inland areas range anywhere from around 80 degrees for the 25th percentile to the low 90s for the 75th percentile for the 4th of July holiday and the following Friday. Current deterministic NBM forecast hedges temperatures to the upper 80s which. -HEC && .AVIATION...Conditions across the area should remain mainly VFR through the day. Broken stratus can be seen below some of the midlevel clouds on satellite imagery, mainly along the northern Oregon and southwest Washington coasts/coast range and lesser so over the cascades. This bit of stratus is around 3000 ft according to the KAST observations from the past 6 hours. HREF guidance suggests this sticking around until around 18-20Z. HREF guidance also suggests a chance (30-50%) for a short period of MVFR CIGs inland between 12-17Z. High pressure offshore will build toward the PNW coast through the day, supporting northwest winds at 10-15 kts along the coast and northerly winds inland around 10 kts. PDX AND APPROACHES...Mainly VFR conditions are expected, though HREF guidance does suggest a chance (30-50%) for MVFR CIGs around 12-17Z, with the highest probabilities around PDX and TTD. Light and variable winds will become northerly around 5-10 kts today as high pressure builds. -Batz && .MARINE...High pressure offshore will continue to build towards the PNW coast today, supporting N/NW winds at 10-15 kts. At same time, thermal low pressure will remain over far southwest Oregon into northwest California. As such, will get back into some northerly winds, with gusts up to 20 kt Friday afternoon, mainly south of Tillamook. Overall, seas staying in the 4 to 5 ft range. Yet another weak low pressure arrives later Sat, with winds flipping back to the west or southwest. Gradients weaker, so winds not expected above 15 kt, while seas stay at 4 to 6 ft. Next week, will see high pressure offshore build, along with the potential for a stronger thermal low along the south Oregon coast, possible reaching to the north. This would tighten the pressure gradient, possibly enough for wind gusts to reach 25-30 kts, warranting a small Craft Advisory. Time frame to keep in mind is next Wednesday and beyond. -Batz && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland