


Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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386 FXUS66 KPDT 171133 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 433 AM PDT Fri Oct 17 2025 Updated Aviation Discussion .DISCUSSION...Today through Saturday Morning: Cloud cover has increased across the region as a shortwave with an attendant cold front will arrive to the PacNW. Light rain showers will develop along mainly the WA Cascade crest with light snow showers mainly above 6.5kft. The cold front passage today will result in breezy to locally windy west to northwest winds through the Cascade gaps (gusts around 30-45 mph) and the Columbia Basin (gusts around 25-35mph). There is moderate confidence (55-70%) that localized areas of the Kittitas valley may see sustained winds around 30 mph with occasional gusts between 45-50mph this afternoon. That said, confidence is too low to issue any wind highlights for the Kittitas valley at this time. Otherwise, while the region is well within the Fall season, there is a moderate concern for elevated fire weather conditions developing this afternoon. CAMs and deterministic model guidance indicate the potential for a very dry airmass (RHs 5-15%) around 700mb to mix down along the WA Cascade east slopes and into the Kittitas valley this afternoon and overlap with strong winds, producing critical fire weather conditions. At this time, confidence is only moderate (55%) in widespread Red Flag conditions this afternoon. Dry conditions with light winds will briefly return to the forecast area late Friday through Saturday morning as an upper level ridge pushes across the PacNW (confidence 80-90%). Saturday Afternoon through Monday Morning: By Saturday afternoon, ensemble guidance continues to be in great agreement of an upper low and surface cold front dropping out of the Gulf of Alaska, then passing over the PacNW Sunday and exiting by late Monday morning. This system will bring with it widespread chances of rain showers and light mountain snow above 5kft, but as compared to model runs from 24 hours ago, rain amounts east of the Cascade crest have been reduced owing to higher confidence (70-85%) in a faster and further north trough passage. Confidence is at least mod-high (65-80%) in rain amounts between 0.5-0.75 inches or higher along the Cascade crest, 0.25-0.5 inches across the northern Blues and the Eagle Cap Wilderness, 0.1-0.2 along the northern Blue mountain foothills and lower Cascade east slopes, with a few hundreths up to 0.1 inches elsewhere. A pressure gradient developing across the Blue Mountains will result in breezy south winds (gusts 25-45mph) developing through the Grande Ronde Valley and north-south oriented canyons/valleys across Wallowa county throughout Saturday night as the trough approaches. Otherwise, the incoming upper trough/cold front will bring breezy west to southwest winds through the Columbia Basin and Cascade gaps Sunday (confidence 70-85%). There is good agreement amongst ensemble guidance that upper level ridging will build back over the PacNW with mostly dry conditions and lingering light showers across the Cascades and portions of the northern Blues Monday. Monday Afternoon through Thursday: Moderate confidence (50-65%) that upper level ridging will persist over the region, but will briefly flatten as a shortwave crosses into southern BC early Tuesday. Light showers along the WA Cascade crest will be possible, but with a stronger shortwave the northern OR Cascade crest may see light showers as well. Good agreement amongst ensemble members in ridging building back over the PacNW with mostly dry conditions(confidence 40-60%) Tuesday night through Wednesday morning. Wednesday afternoon through Thursday, cluster ensemble solutions all depict some form of troughing developing off the PacNW coast with upper level ridging pushing of to the east, though there is disagreement on timing. That said, ensemble guidance favors rain and high mountain snow developing sometime Thursday along the Cascade crest, with dry conditions elsewhere. Lawhorn/82 .AVIATION...12z TAFs...VFR conditions to prevail through the period. Sct-Ovc CIGs will continue over sites through the morning and early afternoon as a weather system moves overhead, with skies clearing by this evening. Winds will increase to 12-15kts with gusts up to 25kts at sites RDM/YKM/ALW/PSC this afternoon; sites DLS/PDT will see strong winds to around 20kts and gusts up to 30kts this afternoon. Winds will weaken to 12kts or less during the evening and early nighttime hours at the aforementioned sites. Winds at site BDN will remain light, 12kts or less, through the period. Lawhorn/82 && .PRELIMINARY POINT TEMPS/POPS... PDT 65 34 64 45 / 0 0 0 40 ALW 64 39 64 47 / 0 0 0 60 PSC 67 32 61 47 / 0 0 0 40 YKM 66 34 59 41 / 0 0 0 60 HRI 67 33 62 46 / 0 0 0 40 ELN 59 28 56 37 / 10 0 10 70 RDM 65 26 70 40 / 0 0 0 20 LGD 63 31 64 44 / 0 0 0 30 GCD 64 31 69 43 / 0 0 0 10 DLS 66 38 65 49 / 10 0 0 60 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ DISCUSSION...82 AVIATION...82