FXUS66 KPQR 310434 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 833 PM PST Mon Jan 30 2023 Updated Aviation section .SYNOPSIS...Strong high pressure will keep SW Washington and NW Oregon dry through Thursday morning. A weak front passing to our north may bring some drizzle to the coast Tuesday night. Temperatures will gradually warm through the week with a return to more active pattern by Friday. && .SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...Clear skies across NW Oregon, SW Washington as high pressure pushes east towards the coast. Clear skies under a subsidence inversion with relaxed winds are allowing daytime temperatures across the high terrain to warm 10-20 degrees warmer than this same time [2 PM] yesterday. GOES-West imagery shows upper level moisture associate with a weak shortwave moving across the northern periphery of the ridge. This shortwave will provide just enough lift to bring some light rain to the northern coast Tuesday night into Wednesday. Inland areas are very likely to stay dry through Wednesday as a continued offshore component to the low level flow should keep most of this moisture from making it east of the Coast Range. Temperature inversions will build through Wednesday as the air mass aloft moderates. The air mass is still looking too dry for fog development tonight through Wednesday night. Moderation and a little more sunshine should allow valleys to warm a bit closer to normal Wednesday. Air stagnation may also result in some deterioration in air quality tonight through Wednesday, but the period of stagnant conditions still remains too short (less than 48 hours) to warrant an advisory. -BMuhlestein/Weagle .LONG TERM...THURSDAY THROUGH SUNDAY...The upper-level ridge over our region is expected to break down and/or move eastward on Thursday, based on ensemble guidance and WPC's 00Z cluster analysis. Following this exiting ridge, an upper- level short-wave trough is expected to move in and bring our next round of precipitation beginning Thursday night into Friday. NBM PoPs show a 40-60% chance of precipitation across our region Thursday afternoon, increasing to a 60-80% chance Friday morning. The majority of WPC clusters agree with this timing; however, 34% of Euro ensemble members suggest that our region will still be under the exiting portion of the ridge. If that were the case, we would likely see precipitation arrive later than currently expected. As we enter this wet pattern, ensemble guidance shows on- shore winds from the southwest/west moving in, which will moderate temperatures across the region to near seasonal values. By Saturday afternoon into Sunday, all cluster analyses agree that a deeper, upper-level trough will begin to move in to our region and bring another round of precipitation. Totals from this system are expected to be higher than the initial Thursday-Friday system. This system will also bring breezy south winds to the area, but forecast wind gusts are less than 25-30 mph. By Sunday afternoon, 80-90% of all members from the GFS, Euro, and Canadian ensembles agree that total precipitation will exceed half an inch. At this time, forecast rain amounts are not high enough to prompt flood concerns. -NAlviz && .AVIATION...06Z TAFs: VFR with thin high clouds as of 0430Z. Little to no change through Tuesday morning then increasing mid and high level clouds. Weak onshore low-level flow late Tuesday afternoon may result in areas of cigs 035-050 along the south Washington and far north Oregon coast in the 00Z-06Z Wednesday time frame. For detailed Pac NW aviation weather information, go online to: http://weather.gov/zse KPDX AND APPROACHES...VFR with just thin high clouds at the terminal and vicinity as of 0430Z. Expect increasing high cloud cover Tuesday afternoon. Weishaar && .MARINE...Buoy observations from 2 PM PST Monday showed relatively light northeast winds around 5 to 10 kt with seas around 5 ft, primarily due to a long period westerly swell. The ongoing long period westerly swell is expected to continue through Wednesday at around 4-5 ft along with sub-small craft criteria winds under 20 kt. The exception will be Wednesday afternoon when wind gusts should increase close to 20-25 kt. For now, will hold off on issuing a small craft advisory on Wednesday given how marginal forecast wind speeds currently are. The main concern in regards to winds and seas is Thursday into Friday when the next Pacific frontal system is set to impact the coastal waters. Although there is still considerable uncertainty regarding exact timing and exact wind speeds with this system, confidence is increasing that gale force wind gusts will occur. In fact, the NBM is showing a 65-75% chance of southerly wind gusts in excess of 34 kt with this system. Even storm force wind gusts cannot be completely ruled out yet, as the NBM suggests there is a 10-20% chance of wind gusts in excess of 48 kt over the outer waters. For now, will continue to forecast wind gusts in the 30-40 kt range, strongest over the outer waters beyond 10 nm offshore. A fresh swell will also build with the increasing winds, likely pushing significant wave heights up to at least 13-16 ft. Seas will likely reach 20 ft or higher if wind gusts end up stronger than 40 kt. -TK && .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