textproduct: Pendleton

AVIATION

A deep dry atmospheric column will contribute to expected widespread VFR conditions through the overnight and Thursday. LAMP guidance suggests light and variable winds for most of the area although north winds 10-12kt at BND and RDM can linger through 02z and and a westerly component through 12z at DLS. Russell/71

PREV DISCUSSION

/issued 210 PM PDT Wed Sep 17 2025/

DISCUSSION...Today through Friday: Quiet, benign weather prevails with warm, dry conditions as the high pressure system gradually moves eastward. However, the thermal trough remains persistent. The approaching upper trough will last tomorrow into Friday, but with both days remaining dry. This weather pattern will keep the high temperatures in the 70s and 80s with a 60-90% probability of reaching in the mid to high 80s. Daytime RHs will remain in the 30s today for lower elevations, though with John Day Highlands and Basin in the mid-teens and low 20s before improving tomorrow onwards.

Saturday through Wednesday: The deterministic models and ensembles do show an agreement for Saturday with the PacNW in between a cutoff low extended across CA coast and an upper ridge over British Columbia. The ECMWF favors light moisture over the eastern mountains Saturday around 5pm from an potential upslope flow, but the GFS has the Cascades with light precip later on that day as well. Overall, this raises a challenge in forecasting the precip due to the timing difference with the frontal system.

However with this pattern and the associated thermal trough, gusty west winds could develop along the Cascade Gaps at 20-30 mph. This may potentially promote elevated fire weather conditions for nearby wildfires. Confidence is low (<30%) at this time, but will be monitored as Saturday comes near. As the frontal system arrives Sunday, showers will develop over the WA/OR Cascades and the Wallowas (15-30% chance). We may have a break Monday through Tuesday early morning with the high pressure building over. Tuesday late morning, showers will return across the Cascades before becoming more widespread Wednesday. Gusty winds will also develop over the Foothills-Blues Mountains of OR and portions of Yakima and Kittitas Valley Sunday afternoon into evening. Rest of this week will light winds with occasional breezes. Feaster/97

AVIATION...18Z TAFs (PREVIOUS DISCUSSION)...VFR conditions prevail through the TAF period with winds less than 12kts. Feaster/97

PRELIMINARY POINT TEMPS/POPS

PDT 84 54 82 56 / 0 0 0 0 ALW 86 58 84 59 / 0 0 0 0 PSC 85 53 85 53 / 0 0 0 0 YKM 87 54 85 54 / 0 0 0 0 HRI 85 54 84 54 / 0 0 0 0 ELN 84 51 82 49 / 0 0 0 0 RDM 83 44 80 48 / 0 0 0 0 LGD 85 49 87 53 / 0 0 0 0 GCD 87 51 88 54 / 0 0 0 0 DLS 87 58 84 57 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None.