275 FXUS66 KPQR 111216 AFDPQR Area Forecast Discussion National Weather Service Portland OR 416 AM PST Tue Nov 11 2025 .SYNOPSIS...Brief high pressure will maintain dry weather through early Wednesday morning. By Wednesday night, a frontal system will approach the region and return cooler temperatures and wet weather. Snow levels fall Thursday into Friday, leading to potential for accumulating snow at the Cascade passes. Unsettled weather is expected to continue through the weekend. && .SHORT TERM...Now through Wednesday night...A shortwave ridge will build over the Pacific Northwest today, maintaining dry weather with seasonable temperatures and light northerly winds. Will see increasing mid to high level cloud cover ahead of the next system. Conditions will remain pretty calm across the region through early Wednesday morning. By Wednesday afternoon, the aforementioned upper ridge will shift eastward and a deeper upper trough over the NE Pacific will approach the region. Based on GFS/Euro ensemble guidance, there is general agreement that the surface low pressure center will track just offshore of the southern Oregon and northern California border. An occluded front associated with this low will swing through northwest Oregon and southwest Washington by late Wednesday night into early Thursday morning, returning widespread rain. Since the low appears to track further south of our area, the heaviest precipitation is forecast to aim toward far northern California and southwest Oregon. Chances for 24 hour total rainfall of 1 inch of greater from 4 PM Wednesday to 4 PM Thursday is around 15-25% across interior lowland valleys, and 60-70% along the coast, Coast Range, Willapa Hills, and north OR/south WA Cascades. Winds will also increase on Thursday and turn more southerly/southwesterly, however based on the currently low track and strength, it does not appear likely that winds would lead to significant impacts. Chances for 24 hour maximum wind gusts of 45 mph or greater on Thursday are only around 10-20% across interior valleys and 20-30% along the coast. These wind gusts could come to fruition in our area if the low ends up becoming stronger and/or tracks further north. If this happens, then there could be isolated impacts including downed trees or power lines, but again it appears unlikely. -10 && .LONG TERM...Thursday to Monday...Once the front pushes through the area Wednesday night, temperatures will become cooler on Thursday. There is a 30-50% chance that 850 mb (5000 ft elevation) temperatures fall to 0 deg C or lower Thursday- Friday. This would potentially bring snow levels down to pass- level in the Cascades. Guidance has trended downward when it comes to snow amounts compared to previous forecast packages due to temperatures trending slightly warmer. There is now a 30-40% chance that 48-hour snow totals between 4 AM Thursday to 4 AM Saturday exceeds 6 inches at Santiam and Willamette Passes, while chances are lower around 20-30% at Highway 26 near Government Camp. Elsewhere, rain continues on Thursday as low pressure remains over the region. Thunderstorm chances on Thursday have lowered to around 5-10% as CAPE/instability is appearing more marginal (50-100 J/kg). An isolated thunderstorm still can't be ruled out still, which could produce lightning, heavy downpours, gusty outflow winds, and/or small hail. Active weather continues Friday through the weekend with snow levels forecast at pass-level through Friday morning. On Saturday, another frontal system will bring in a warm front that will raise snow levels and return rain in the Cascades. However, it'll be brief as the trailing cold front will push through Sunday and bring snow levels back-down to pass-level heading into early next week, returning snow chances through Santiam/Willamette Pass and Highway 26. Chances for rain continues everywhere else through Monday. -10 && .AVIATION...Satellite imagery and terminal observations as of early Tuesday morning show a widespread mix of IFR/MVFR and low- end VFR CIGs across the Willamette Valley and coast. High pressure aloft and a moist low level atmosphere will likely (60-80% chance) maintain IFR/MVFR CIGs through 18-21z Tue. An exception would be the north Oregon coast (KAST), which has cleared up. In this area, could see some LIFR/IFR conditions due to fog or mist development. Low stratus and any fog should clear out by early afternoon as mixing increases due to daytime heating. Predominately VFR thresholds with high- level BKN/OVC clouds return after 21z Tue. Winds will generally be northerly to northeasterly under 5 kt today across all terminals. KPDX AND APPROACHES...MVFR CIGs with occasional breaks to low- end VFR through 18z Tue. Predominately VFR thresholds return after 18z Tue with high-level BKN/OVC clouds. Northwesterly winds today under 5 kt. -10 && .MARINE...High pressure over the waters will maintain calm marine conditions through early Wednesday morning. Winds will generally remain northerly with gusts less than 10 kt and seas of 5-8 ft at 10-13 sec. The next low pressure system in the NE Pacific will return breezy southerly winds and building seas Wednesday into Thursday, with high confidence for another period of conditions hazardous to small craft. As this system swings a front through the waters, there's a 60-80% chance of frequent southerly wind gusts exceeding 21 kt and a greater than 90% chance that seas build above 10 ft by late Wednesday night/early Thursday morning. Therefore, a Small Craft Advisory has been issued for all marine zones including the Columbia River Bar from 10 AM Wednesday to 10 AM Thursday. During this time, there is also a 40-60% chance for isolated gale-force wind gusts greater than 34 kt, with the highest chances across the outer waters beyond 20-30 NM. Active weather continues into the end of the week with additional systems moving through the waters. -10 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 10 AM Wednesday to 10 AM PST Thursday for PZZ210-251>253-271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland