FXUS66 KPDT 220529 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1029 PM PDT Fri Aug 21 2026 .KEY MESSAGES... - Heat Advisories remain in effect through 10 PM. - Very low to slight chance (5-20 percent) of high-based showers and thunderstorms today and Saturday. Red Flag Warnings in effect for several fire weather zones. - Widespread breezy to windy westerly winds coupled with low relative humidity Saturday. Red Flag Warnings in effect for numerous fire weather zones. Wind Advisories in effect. && .DISCUSSION... Water vapor imagery shows a large, closed low offshore in the Pacific, just west of the OR/CA border. Meanwhile, an upper- level ridge of high pressure extends from the Four Corners into the Pacific Northwest. The interaction of these two synoptic- scale features will drive the bulk of our weather over the next couple days. Under the ridge, widespread hot conditions are in place with afternoon high temperatures already in the 90s to lower 100s this afternoon. Temperatures are expected to continue climbing in areas bereft of significant mid/high cloud. Clouds draped over the western half of our forecast area will suppress daytime highs relative to yesterday. Heat Advisories remain in effect through 10 PM this evening due to widespread Moderate (level 2 of 4) to Major (level 3 of 4) HeatRisk. This level of heat affects anyone without cooling/hydration. Ensemble NWP guidance is in concensus that the upper low will slowly track north-northeast through the day, remaining just offshore. This places the forecast area under southerly to southwesterly flow aloft. Synoptic-scale forcing coupled with increasing mid-level moisture may facilitate some high-based showers and thunderstorms this afternoon, tonight, and into Saturday morning, but probabilities are quite low (5-15 percent), highest for the Cascades. The low is then expected (95 percent confidence) to track inland across northern Oregon and Washington during the day Saturday, morphing into an open-wave trough as it moves inland. Its attendant cold frontal passage during the day will help drive breezy to windy westerly winds through the Cascade gaps as well as across the Columbia Basin and portions of the Blue Mountains. Wind Advisories were issued for many public forecast zones across north-central Oregon and south-central Washington, and may be expanded should confidence increase in windy conditions extending farther east across the Columbia Basin and Blue Mountain foothills. While confidence was "only" medium-high (50-90%) in reaching rh thresholds across fire weather zones, due to the magnitude of the forecast winds (10-25 mph with gusts of 25-40 mph, locally higher through especially wind-prone areas), have issued Red Flag Warnings for wind and low relative humidity for the majority of our non-mountain fire weather zones for later Saturday morning (OR/WA693) or Saturday afternoon (WA690, WA691, OR691, OR696, OR698, OR700, and OR703). In addition to Red Flag Warnings for wind/rh, the potential for abundant lightning and gusty outflow winds prompted Red Flag Warnings for WA695 (tonight through Saturday morning) and OR/WA692 (late Saturday morning through Saturday evening). Some breezy conditions are forecast to linger Sunday as the trough exits to the east. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... VFR conditions are expected through Saturday. Winds will gust in the 25 to 30 kt range at all sites except ALW and PSC. The stronger winds across the region will hopefully prevent major issues with smoke, though there could still be some local smoke from the regional wildfires. && .Preliminary Point Temps/PoPs... PDT 63 90 50 83 / 10 10 0 0 ALW 70 93 58 84 / 10 0 0 0 PSC 67 96 58 86 / 10 100 0 YKM 71 95 58 86 / 10 30 0 0 HRI 69 92 58 85 / 10 10 0 0 ELN 66 87 54 79 / 10 30 0 0 RDM 55 89 44 84 / 10 10 0 0 LGD 65 95 52 86 / 10 10 10 0 GCD 64 95 53 88 / 10 10 0 0 DLS 67 85 60 84 / 20 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...Air Quality Alert until noon PDT Monday for WAZ026-522-523. Wind Advisory from 11 AM to 11 PM PDT Saturday for WAZ024-521. Red Flag Warning from noon to 10 PM PDT Saturday for WAZ690- 691. Red Flag Warning from 11 AM to 11 PM PDT Saturday for WAZ692. Red Flag Warning from 10 AM to 8 PM PDT Saturday for WAZ693. Wind Advisory from 2 PM to 10 PM PDT Saturday for WAZ026. Red Flag Warning until noon PDT Saturday for WAZ695. OR...Air Quality Alert until noon PDT Monday for ORZ041-044-049-050- 502-503-505>507-509>511. Wind Advisory from 11 AM to 11 PM PDT Saturday for ORZ041-044- 508-510. Red Flag Warning from noon to 10 PM PDT Saturday for ORZ691- 696-698-700-703. Red Flag Warning from 11 AM to 11 PM PDT Saturday for ORZ692. Red Flag Warning from 10 AM to 8 PM PDT Saturday for ORZ693. && $$ DISCUSSION...86 AVIATION...77