FXUS66 KPDT 160519 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1019 PM PDT Thu Oct 15 2026 .KEY MESSAGES... 1. Dry and warm conditions through the end of the week 2. Gusty conditions through the Grande Ronde Valley tomorrow afternoon with elevated fire risk. 3. Trough develops through area beginning Monday with the potential for rainfall along Blue Mountains && .DISCUSSION... Clear skies continue to be present over the region thanks to continued upper-level ridging along the US West Coast. Current guidance timing suggests that the ridge will remain present in the region throughout the rest of today and tomorrow, transitioning to zonal flow alongside a shortwave trough tomorrow night into Saturday morning. Said shortwave trough will likely (greater than 50% chance) be positioned along the US- Canada border, limiting precipitation chances through the region (less than 20%). As the primary trough axis continues to move eastward, deterministic guidance highlights a favorable surface pressure gradient across the Blue Mountains for gusty south/southeast winds tomorrow into Saturday morning, especially around the Grande Ronde Valley. NBM ensemble probabilities for this time show a high chance (around 75%) of localized sustained winds in excess of 20 mph, with a moderate chance (up to 50%) of local gusts in excess of 40mph in the Grande Ronde Valley. Given the windy conditions in these regions, as well as RH values around 15-20% for much of the Blue Mountains in the afternoon, an elevated fire risk is present for these regions for Friday afternoon into the evening. As zonal flow continues throughout the weekend, an upper level trough will begin to develop offshore Sunday night through Monday, moving into the PacNW region Monday night into Tuesday. Ensemble guidance is confident (greater than 75% chance) that a trough will occur, however significant variability still exists regarding trough strength and timing. Because of this uncertainty in trough depth, there is low confidence (around 30-40%) in current rainfall amounts. In scenarios where the trough is deeper, with a closed low developing near California, rainfall is limited to non-wetting amounts along the Blue Mountains. In scenarios with a more northward low or open wave setup, wetting rainfall in these regions is more likely with the improved moisture flow pattern. Lingering rainfall is possible into Wednesday and Thursday as the trough moves eastward and weakens, however the same model variability concerns and low confidence still applies. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... VFR Conditions prevail. Winds follow a diurnal pattern. && .Preliminary Point Temps/PoPs... PDT 37 73 41 69 / 0 0 0 0 ALW 44 74 49 69 / 0 0 0 0 PSC 38 69 37 71 / 0 0 0 0 YKM 42 70 42 69 / 0 0 0 0 HRI 37 70 38 70 / 0 0 0 0 ELN 38 67 39 61 / 0 0 0 0 RDM 33 79 34 66 / 0 0 0 0 LGD 41 71 45 70 / 0 0 0 0 GCD 36 76 37 72 / 0 0 0 0 DLS 44 75 46 69 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...21/71 AVIATION...18