textproduct: Pendleton

EVENING UPDATE

Temperatures remain near or below freezing across the majority of the Columbia Basin and surrounding lowlands. While the steadiest freezing rain has ended or is tapering off in the areas under a Winter Weather Advisory, after collaboration with surrounding offices, opted to extend the advisories until 7 AM PST Friday morning due to additional intermittent precipitation that is forecast to continue overnight into the early morning hours.

AVIATION...06Z TAFs

The steadiest precipitation (FZRA for all but RDM/BDN/DLS) has ended or is tapering off for TAF sites. Intermittent precipitation is forecast to continue overnight into the morning hours, especially at ALW, with mostly dry conditions returning by Friday afternoon. Confidence is very high (80-100 percent) in at least periods of sub-VFR conditions due to low CIGs and/or VSBYs at all sites except RDM/BDN where confidence in sub- VFR conditions is 40-60 percent overnight. Sustained winds of 10 kts or less are forecast at all sites.

PREV DISCUSSION

/issued 233 PM PST Thu Jan 1 2026/

KEY MESSAGES...

- Freezing Rain Risk continues Tonight before ending south to north early Friday Morning DISCUSSION...

Air stagnation advisory was allowed to expire as precipitation becomes onset This Afternoon into Tonight, followed by a marked eastward shift of the mid level ridge from the Interior NW into the Nrn Rockies. The consensus of short term models has a slightly cooler trend for Todays highs and was used for short terms updates, actually undercutting the HRRR by about a degree in some areas of south central WA. The lifting warm front has warmed temperatures sufficiently across the Bend and Redmond areas to allow the winter weather advisory to expire on time. At the same time freezing rain has become established at PDT with early afternoon temperature remaining steady at 30F. LAMP guidance keeps the temps below freezing though 11z Saturday, maintaining the freezing rain threat, although precipitation might end well before then. Freezing Rain accumulation model and NBM expected ice accumulations are averaging from around a light glaze to about 0.05 of ice across a large portion of the lower Columbia Basin and eastern Columbia River Gorge, into the Kittitas and Yakima valleys. Enhanced expected amounts are seen over the Blue Mountain foothills where closer to one tenth of an inch is more common, while highest amount are expected in the WA Cascade Upper Slopes. Trends on HREF continue to show the last of the light FZRA accumulations exiting the south central/southeast WA before 18z Saturday. The surface pressure gradient is forecast to increase dramatically Saturday night into Sunday across the Grande Ronde Valley, pointing to a period of potentially strong gusty winds to 50 mph. The deterministic NAM peaks at around 10 mph midnight Saturday while SREF (ensembles ) leave a little more uncertainty in the strength of this gradient. Friday likewise will bring a bump in temperatures to the 40s across the lowlands and low 50s at crest where better wind mixing will be present. The rest of the 7 day forecast period is relatively mild in terms of impacts. Saturday into Sunday might bring some mountains snows and breezy winds in addition to lowland showers. Another signal points to WA Cascade Upper Slopes snows by Tuesday and Wednesday.

PRELIMINARY POINT TEMPS/POPS

PDT 29 48 34 50 / 80 40 10 40 ALW 30 44 36 48 / 90 70 10 60 PSC 27 41 31 45 / 80 30 10 50 YKM 28 41 32 43 / 60 20 20 50 HRI 28 42 32 46 / 80 30 10 40 ELN 27 38 31 40 / 60 40 40 70 RDM 34 52 36 53 / 60 0 10 20 LGD 35 45 38 48 / 90 70 0 50 GCD 38 50 36 50 / 90 30 10 50 DLS 32 44 37 45 / 90 50 40 60

PDT WATCHES/WARNINGS/ADVISORIES

OR...Winter Weather Advisory until 7 AM PST Friday for ORZ041-044-507- 508-510.

WA...Winter Weather Advisory until 7 AM PST Friday for WAZ024-026>029- 521>523.