Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
137 FXUS66 KPQR 181826 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 1124 AM PDT Wed Sep 18 2024 Updated public and aviation discussions... .SYNOPSIS...Upper low will pass to the south today, with lingering clouds, mainly to south and east of Salem. Otherwise, high pressure will return, with dry weather and bit below seasonal temperatures under variable onshore flow. Another front will bring a chance of showers Sunday into Monday. Does appear will see warmer temperatures next week, maybe as much model uncertainty at this time. && .SHORT TERM...Now through Friday...As the day progresses, will see the upper low sink farther to the south, with high pressure building into Oregon. This will return dry weather with clouds gradually giving way to partly to mostly sunny skies. Will be warmer, with temperatures back into the 60s along the coast, and upper 60s to lower 70s across the interior. Not much change tonight into Friday, as will maintain high pressure offshore. As such, will have variable light to moderate onshore flow. Overall, rather pleasant late September weather, with patchy fog/low clouds for overnight/early morning hours along with overnight lows mostly in the upper 40s to lower 50s. Days will be quite pleasant, with highs in the 60s along the coast, and lower to middle 70s farther inland. -Rockey/Alviz .LONG TERM...Saturday through Tuesday... Forecast confidence remains below normal this weekend into the early part of next week as model solutions continue to diverge significantly with regard to how the upper level pattern evolves. Ensemble clusters remain just about evenly split in depicting ridging, troughing, and zonal flow regimes over the Pacific Northwest from Saturday through Monday. This obviously will have large implications for the forecast as anything ranging from warm and dry weather to a cooler and wetter pattern remains on the table for days 5-7. This continues to be reflected in the NBM interquartile ranges for temperatures which range anywhere from the upper 60s to the upper 70s between the 25th and 75th percentile guidance. As such, and until models begin to converge on a solution, have opted to stick with the NBM mean which splits the difference between these solutions and depicts broad- brushed chance to slight chance PoPs over the area late this weekend through early next week. /CB && .AVIATION...Northeast flow aloft as upper ridge of high pressure gradually builds over the region today. As of 18z Wednesday, widespread MVFR CIGs are expected to gradually improve later this morning through early afternoon, becoming predominately VFR by 20- 22z Wed. Stratus is then expected to develop again at the coast around 03-05z Thursday with conditions likely (60-80% chance) deteriorating to IFR tonight. Stratus also likely (60-80% chance) builds across inland terminals after 12z Thursday with MVFR CIGs trending toward 1500-2000 ft. Generally expect north to northwest winds, increasing to around 10 kt this afternoon. PDX APPROACHES...MVFR stratus has filled back in this morning with CIGs around 1500-2500 ft. Stratus expected to break up and lift to VFR around 20z Wed afternoon, and continue to scatter out through this evening. MVFR stratus likely (60-70% chance) to redevelop after 12z Thursday. Expect light northwest winds to increase to around 6-8 kt by this afternoon. /DH && .MARINE...High pressure returns to the coastal waters today as the system from Tuesday departs to the south. As a result will see northerly winds return today and continue through the week. Winds may gust 20 to 25 kt at times, primarily over the outer zones. The high pressure should weaken over the weekend, as will winds. Seas around 6 ft today increasing to around 8 ft later tonight into into Thursday, then settling to around 5 ft late in the week. /mh && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 4 PM this afternoon to 9 PM PDT this evening for PZZ210. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland