textproduct: Pendleton

UPDATED AVIATION...18Z TAFs

BDN/RDM are at VFR and will continue to see VFR conditions through the period. DLS/PDT/PSC/ALW are all MVFR due to lower VSBYs 4-6SM due to BR and low CIGs below 3kft. YKM sits at IFR due to very low CIGs below 700 ft and 4SM due to BR. This will continue through 21-00Z as winds will pick up across all TAF sits assisting with the push out of the fog and the lifting of the CIGs.

A warm front will come across the region bringing with it continued rainfall and an increase in the winds (80-90% probabilities). Timing of the warm front crossing will be the toughest part of the forecast, however, models show the front to move across between 21-00Z. Wind advisories have been put out across the many of the TAF due to winds nearing 30kts sustained and 35-40 kt gusts. BDN/RDM will also see higher winds 10-20 sustained with gusts of 25-30 kt. With the assistance of the winds, all TAF sites will see VFR conditions after 21Z (60-80%). 90

PREV DISCUSSION

/issued 408 AM PST Fri Dec 5 2025/

DISCUSSION...

Key Messages:

1. Breezy to windy conditions this afternoon through Saturday afternoon. Wind advisories expanded both temporally and spatially.

2. Persistent rain chances through the next week combined with high snow levels will lead to rises on area rivers.

Overview: The forecast for the next week can be succinctly described as warm, wet, and windy as a subtropical high in the Pacific combines with a remarkably persistent quasi-zonal to zonal jet stream and multiple frontal systems to direct several rounds of subtropical to tropical moisture into the Pacific Northwest.

Headline updates: The main update to headlines was the expansion of existing wind advisories to include the Yakima Valley, Lower Columbia Basin of Washington, and the Wallowa Valley.

Rain is beginning to overspread the forecast area again as low- to mid-level warm air advection (WAA) associated with a warm frontal passage this morning interacts with ample moisture. The result will be the best precipitation chances for the lower elevations through the remainder of the week. For mountain areas, especially the Cascade crest and northern Blues, precipitation chances will be more persistent into the weekend.

The main talking point today is the anticipated breezy to windy westerly (southwesterly to northwesterly depending on the exact location) winds that are poised to ramp later this afternoon through tonight as a strong jet moves overhead. This afternoon through Saturday morning, the 00Z HREF places a persistent 8-12 hPa pressure difference between PDX and GEG -- often the threshold where advisory-level winds begin -- and an 850-hPa jet of 40-60 kts over the Columbia Basin. While the largely nocturnal nature of the event does reduce overall forecast confidence in persistent, widespread advisory-level winds through the entire advisory period, confidence is still high (70-95%) that peak gusts will exceed 45 mph in wind-prone locations. Moreover, per NBM calibrated probabilities, there is still a low-medium chance (20-50%) of reaching or exceeding warning-level gusts in the most wind-prone locations of the Columbia Plateau.

Snow levels today will remain high enough (generally 5-8 kft) to preclude any concerns for winter weather headlines, though a cooler air mass tonight through Saturday night will present lower snow levels (4-5 kft) and at a medium chance (50%) of advisory- level snowfall for White Pass. Through the bulk of the next week, snow levels are then forecast to remain high at mostly 5-8 kft with periodic dips to 4.5 kft along the Washington Cascades.

Lastly, will note a significant amount of precipitation is forecast for the mountain areas Monday through Thursday of next week. While confidence in precise amounts is still low, and will depend on the exact location of the jet stream and incoming frontal systems, the NBM places a 20-30% chance of reaching or exceeding 5 inches of liquid equivalent across the Oregon Cascade crest through the 72-hr period ending 4 AM Thursday, and an even higher 40-50% chance for the Washington Cascades. Since much of this precipitation is forecast to fall as rain, rises on area rivers are anticipated. Current forecasts from the NWRFC in Portland do place multiple rivers near or above action stage by the latter half of next week.

PRELIMINARY POINT TEMPS/POPS

PDT 41 52 39 53 / 40 40 30 70 ALW 42 52 41 52 / 60 50 50 80 PSC 41 56 39 54 / 10 10 10 60 YKM 38 55 34 51 / 30 20 20 70 HRI 42 55 39 55 / 20 20 20 70 ELN 36 48 32 46 / 60 40 30 70 RDM 32 50 32 53 / 40 10 10 40 LGD 38 46 34 44 / 80 80 60 80 GCD 35 46 33 48 / 60 40 40 70 DLS 47 55 44 54 / 70 70 80 90

PDT WATCHES/WARNINGS/ADVISORIES

OR...Wind Advisory from 1 PM this afternoon to 10 AM PST Saturday for ORZ041-044-507-508-510.

Wind Advisory from 1 PM this afternoon to 1 PM PST Saturday for ORZ050.

WA...Wind Advisory from 1 PM this afternoon to 10 AM PST Saturday for WAZ024-521.

Wind Advisory from 7 PM this evening to 7 AM PST Saturday for WAZ026>029.