textproduct: Pendleton

PREV DISCUSSION

/issued 256 PM PST Tue Jan 27 2026/

DISCUSSION...Through this Evening: Upper level ridging over the PacNW continues to push east this afternoon, with mid to upper level cloud cover starting to spread northeast. There has been a few breaks in the clouds today, allowing some areas of central OR, Columbia Basin, and adjacent valleys to warm into the upper 30s to mid 40s. The remainder of the lower elevations have remained cool through this afternoon, owing to cloud cover aloft and haze near the surface, but have managed to warm above freezing. Not expecting much change in these temperature trends through the remainder of the daylight hours, as the cold pool impacting most of the region will result in temperatures quickly dropping to or below freezing through this evening.

Tonight through Friday Evening: A series of shortwave troughs with attendant surface fronts will impact the forecast area starting tonight, with precipitation chances persisting at least in the mountains through Friday evening. The first of these shortwaves will lift northeast across the PacNW tonight through Wednesday morning, bringing the highest precipitation chances to the Cascade crest, Wallowas, and the Northern Blues through mid morning Wednesday. While the mountains will see light to moderate snow accumulations, the main precipitation concerns will revolve around a wintry mix in the lower elevations, specifically the potential for light freezing rain, as forecast models indicate a warm tongue extending across portions of the lower elevations. Confidence is moderate (50-75%) that pockets of central OR, the OR Columbia Basin, and adjacent Blue mountain foothills will see light freezing rain mix with rain, while a mix of snow and freezing rain is favored in the WA Columbia Basin and adjacent valleys. Snow accumulations in the aforementioned areas will amount to a dusting, while freezing rain accumulations across all the lower elevations will be under 0.05". That said, global and hires ensembles are in disagreement in impacted locations and accumulations, owing to poor handling of the persistent surface cold air pool, cloud cover aloft, and strength of the incoming front/shortwave. As such, this has resulted in low confidence (15-20%) in widespread freezing rain impacts.

Light snow will continue across the Cascade crest and upper east slopes through Wednesday, with chances increasing again Wednesday night through Thursday as the next shortwave impacts the region. This next system is expected to have better moisture support, which translates to higher chances of lower elevation precipitation. Ensemble and NBM guidance is mostly in favor of mostly rain in the lower elevations with pockets of freezing rain along the lower portions of the Cascade east slope valleys. That said, the coldest ensemble members (mostly made up of the Canadian ensemble suite) keep the cold air pool in place across the lower elevations, resulting in more widespread freezing rain chances Wednesday night. While a majority of models bring warmer conditions, they have also continued to handle the cold pool poorly over the past few weeks, so forecaster confidence in precipitation type is low-mod (15-35%) for Wednesday night. Confidence in either solution will grow tomorrow depending on how temperatures trends shake out in the lower elevations.

A ridge will briefly amplify over the region Thursday, but flatten as the last of the series of shortwaves slides across the PacNW Thursday night. Overall, guidance is in favor of warming conditions across much of the PacNW, with snow levels rising to above 5.5kft to 6kft Thursday night. That said, this last system will have a weak moisture plume that will result in the best precipitation chances across the Cascade crest with a trace at best east of the crest. By Friday evening, upper level ridging will redevelop over the PacNW, resulting in drying conditions.

Friday Night through Monday: Ensemble guidance in good agreement of starting the weekend off with dry and mild conditions across the forecast area as an upper ridge parks across the region through Sunday morning. By Sunday afternoon, a shortwave will arrive to the PacNW and lift northeast through Monday, bringing with it a chance of light precipitation across the mountains and lower elevations of the forecast area(confidence 30-60%). Lawhorn/82

UPDATED AVIATION...06Z TAFs

VFR conditions will persist through the start of the forecast period. Low clouds will begin to move over the forecast area from west to east lowering CIGs to near 5000 with a 30% chance of DLS seeing CIGs as low as 2500 feet by 13Z. As the system sweeps across, increased chances at YKM/PDT/ALW/PSC will see <30% chances of freezing rain beginning around 06Z-15Z with ALW seeing a chance of 4SM during the event (30%). Winds will br primarily light and variable through the period. 90

PRELIMINARY POINT TEMPS/POPS

PDT 25 46 35 52 / 30 30 20 40 ALW 27 43 37 50 / 30 50 20 60 PSC 25 43 34 48 / 20 20 30 50 YKM 24 38 32 43 / 20 20 40 60 HRI 24 43 34 50 / 20 20 30 40 ELN 23 35 31 39 / 20 30 60 80 RDM 23 45 32 50 / 20 10 20 20 LGD 30 45 32 43 / 40 50 10 50 GCD 27 45 32 45 / 50 20 20 50 DLS 28 42 37 46 / 50 50 80 80

PDT WATCHES/WARNINGS/ADVISORIES

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