Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
981 FXUS66 KPQR 220445 AFDPQR Area Forecast Discussion National Weather Service Portland OR 945 PM PDT Mon Jul 21 2025 Updated aviation discussion. && .SYNOPSIS...Scattered showers with a 15-20% chance of thunder over the Cascade crest north of Clackamas County this evening. Dry and much warmer conditions return midweek, peaking Wednesday with inland highs reaching well into the 80s and into the low 90s. A gradual cooling trend is likely by the weekend. && .SHORT TERM...Now through Wednesday Night...Visible satellite imagery shows partly cloudy skies across NW Oregon and SW Washington Monday afternoon. The rain showers that passed through the region this morning have mainly moved east of the Cascades, though isolated showers continue over the Cascade crest along and north of Hood River County through the evening. There`s a 15-25% chance of these showers becoming strong enough to produce some lightning, though heavy rain will be the main impact with any strengthening cell. As the low pressure system that is causing these showers continues moving east of the Cascades into tomorrow, high pressure builds in over the region from the west. Temperatures will warm each day, peaking in the mid to upper 80s inland tomorrow and upper 80s to low 90s on Wednesday. Wednesday will be the hottest day of the week with widespread Moderate HeatRisk across the interior lowlands. However, overnight temperatures will remain in the 50s to low 60s which is enough to provide overnight relief from the heat. Onshore flow will continue in this pattern, which will allow for the formation of coastal stratus and fog each evening into the morning hours. Some marine stratus may push east into the valley in the early morning hours, though should dissipate by the late morning hours. -HEC .LONG TERM...Thursday through Saturday...The warm spell tapers off toward the end of the week as ensemble guidance shows broad troughing returning to the Pacific Northwest. Temperatures are forecast to trend back toward seasonal norms by Friday and Saturday, with inland highs settling into the low to mid 80s, and coastal areas holding in the 60s to low 70s. There remains low confidence in a small upper-level low off the California coast influencing our weather by late week. While most ensemble members keep it too far south to affect our area, a low- probability chance (10-20%) of thunderstorms over the Lane and Linn County Cascades on Thursday or Friday cannot be ruled out. At this time, storm coverage appears too uncertain to include in the official forecast, but it remains something to monitor. ~Hall && .AVIATION...MVFR CIGs remain around KAST and are expected to persist or lower to IFR overnight. The marine layer can be see a few miles off the rest of the north/central OR coast and is expected to deepen and move inland along the coast. Marine stratus should fill in along the central Oregon coast late this evening with IFR ceilings for the coast tonight through mid Tuesday morning. There is an 80% chance of ceilings below 1000 feet along the coast from through 17z Tuesday. The latest HREF has increased probabilities for a period of IFR/MVFR CIGs throughout much of the Willamette Valley. Chances from KSLE to KEUG are 20-30% from 12-17z. Winds light and variable overnight, increasing to 5-10 kt from the N/NW after 18-20z. PDX AND APPROACHES...Mainly VFR conditions through the TAF period. There is a 20-40% chance for MVFR/IFR CIGs between 10-17z. Winds light and variable, increasing from the NW around 5-10 kt late Tuesday morning. -Batz/TJ && .MARINE...Weak high pressure will maintain light north- northwest winds through Saturday. The seas are mostly wind- driven, and will be between 2 and 4 feet. ~TJ && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland