Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
969 FXUS66 KPQR 240355 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 855 PM PDT Sun Jun 23 2024 Aviation Discussion Updated... .SYNOPSIS...Dry on Monday as a transient shortwave ridge will bring a brief warmup across the region Monday and Tuesday. An upper level trough brings relatively cooler temperatures for the middle of the week along with periodic chances for rain showers. Warm and dry conditions return for next weekend. && .SHORT TERM...Tonight through Wednesday Night...Cooler and moister conditions today will give way to dry conditions Monday as an upper level ridge develops over the region through Tuesday. So, for the start of this week, look for daytime highs in the upper 70s to upper 80s for inland locations, mid 70s to mid 80s for the Cascades and low 60s to low 70s for the coast, with the warmest day expected on Tuesday. On Tuesday there remains around a 25% probability for daytime highs to creep into the low 90s and around a 5% probability to see daytime highs in the mid 90s for inland locations. As the upper level ridge develops, a weak, thermally induced low will result in increasing, northerly winds for the Willamette Valley, with gusts up to 20 mph possible on Monday. High resolution and deterministic models do show that the aforementioned upper level will quickly push eastward as the next system from the Gulf of Alaska brings another round of cooler, near seasonal temperatures for Wednesday with high temps in the mid to upper 70s for inland locations, low 60 to low 70s for the Cascades and mid 50s to mid 60s for the coast. This trough will also bring increasing chances for rain showers for the majority of the CWA. Overall timing of this precipitation is still under review, but at this time, conditions are looking to be moderate PoPs, but low QPF. Still, have moderate confidence in most locations seeing some measurable precipitation by early Thursday morning. It should be noted that the system on Wednesday is resulting in favorable flow pattern for thunderstorm development along the Cascades with around a 5-10% probability at this time. /42 && .LONG TERM...THURSDAY THROUGH SUNDAY...A shortwave trough continues pushing through the area on Thursday, bringing cooler temperatures and some light rainfall. Daytime highs will fall to the low 70s for inland areas. Rainfall looks light during daytime hours, with even high end scenarios (10% chance) showing rainfall around 0.25", and only in the northern areas (southeast WA). Rain should end around evening-time as the trough moves out of the area, after which the night looks dry and cool. Friday sees zonal flow, with no chance for precipitation. Temperatures begin to warm again, with a 30-40% chance of temperatures above 80 in the Willamette Valley. WPC Cluster Analysis shows continued trending towards some kind of ridging developing over the weekend, but not much certainty yet regarding timing or exact location. Expect warmer temperatures and generally drier conditions. /JLiu && .AVIATION...Moderate onshore flow continues, with VFR conditions throughout the region (CIGS 4000 to 6000 ft). Clouds continue to break apart through tonight, with areas south of KMMV already clear. Will see some brief morning clouds Monday morning along the coast between 07-17Z Monday, with the chance of lowering to MVFR CIGs around 50-70%. Should return to VFR conditions thereafter (probability to stay MVFR around 10-20%). Inland terminals will have prevailing VFR conditions, except for a small chance of MVFR conditions between 11-17Z Monday (10-20% probability). Low level flow will turn north to northeasterly around 12Z Monday, then turn back to north to northwesterly by 16Z Monday. Winds will increase and gust up to 25 kt along the coast and up to 20 kt inland from 17Z Monday to 04-06Z Tuesday. PDX AND APPROACHES...VFR with broken clouds at 5000 to 7000 ft, gradually giving way to mostly clear skies by 05-06Z Monday. Will be predominantly VFR through the TAF period, except for a 10-20% chance of broken MVFR CIGs between 10Z to 17Z Monday. -JH && .MARINE...High pressure will expand across the waters through Monday, while thermal low pressure strengthens over far northwest Calif into far sw Oregon. This will tighten the northerly pressure gradient on Monday, enough to allow north winds to pop 20 to 25 kt gusts Mon afternoon into Mon evening. But, this mainly over the waters off the west central Oregon coast. As such, will put up Small Craft Advisory for said conditions. Otherwise, not much change in the pattern for early this week, as high pressure remains anchored off the Pac NW. Low pressure will arrive mid-week, with a weakening front arriving. This will bring return of unsettled weather, with return of west to southwest winds, but still mostly 15 kt or less. /Rockey && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 4 AM to 10 AM PDT Monday for PZZ210. Small Craft Advisory from 2 PM Monday to midnight PDT Monday night for PZZ253-273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland