textproduct: Pendleton

AVIATION

06Z TAFS...VFR conditions are expected through the TAF period. The only potential caveats are overnight and toward morning with MVFR possible at BDN, RDM and YKM, though it can not be ruled out elsewhere. Confidence is no higher than 30 to 40 percent at any location.

PREV DISCUSSION

/issued 258 PM PST Sun Jan 4 2026/

DISCUSSION...Key Messages:

1. Significant mountain snowfall midweek. *Winter Storm Watches Issued*

2. Breezy winds Tuesday, returning Thursday.

Current radar and visible satellite imagery shows light returns along the Blue Mountains and Cascade crest under partly to mostly cloudy skies. This is a result of an upper level trough offshore that will slowly pass through the Pacific Northwest through Monday. This trough, coupled with two weak cold fronts, will drop high temperatures 5 to 10 degrees on Monday and allow for light mountain snowfall to persist, up to 2 inches likely (80-90% confidence) at pass-level over the Cascades.

The colder air will continue to advect into the area into Tuesday as an upper level system, and associated strong cold front will continue to drive snow levels down from 3500-4500 feet today to 1500- 2500 feet Monday evening. A weak Atmospheric River (AR) will also be present both Tuesday and Wednesday associated with the passing upper level shortwave and frontal system, bringing substantial moisture and periods of heavy snowfall across our Cascade and Northern Blue Mountains. Daily snow totals of 6-14 inches is currently forecast (60-80% confidence) at pass-level across the Cascades. The Northern Blue Mountains are expected to get slightly less, with snow totals of 5-10 inches Tuesday and 3-6 inches Wednesday across elevations above 4000 feet and above. Mountain snowfall continues through Thursday afternoon, as an additional 6-12 inches is expected across the Cascade passes and 3-6 inches over the Northern Blue Mountains. The NBM advertises a 50-80% chance of Cascade passes receiving 7 inches of daily snowfall Tuesday and Wednesday, with Tuesday's chances for the Washington Cascades being 70-80%. The chance of 6 inches or more snowfall over the Northern Blue Mountains on Tuesday is 65-75% and 20-40% on Wednesday via the NBM. Thus, Winter Storm Watches have been issued across the Cascades and Northern Blue Mountains valid 4 AM Tuesday through 4 PM Thursday as total snow amounts of 20-30 inches over the Cascade passes and 10-20 inches across the northern Blue Mountains will be possible. The NBM suggests a 65-95% chance of 20 inches of snow or more across the Cascades and a 50-70% of 15 inches of snow or more along the Northern Blue Mountains during this timeframe.

The incoming system will not only bring with it cooler temperatures, lower snow levels, and moderate to heavy mountain snowfall, but also breezy winds across much of the area. A strong, passing cold front from the northwest will be the feature on Tuesday to bring sustained southwest winds of 20-30 mph and gusts up to 40 mph across the east slopes of the Cascades, Simcoe Highlands, Lower Columbia Basin, and the Blue Mountain foothills. Winds are expected to steadily increase through the day as the front approaches, peaking after 4 PM. Northwest flow aloft and at the surface will continue to bring a cooler airmass through the region as an upper level trough drops along the British Columbia coast and passes through the area Thursday morning. This will return sustained west-southwest winds of 20-30 mph and gusts up to 40 mph to the east slopes of the Cascades, Simcoe Highlands, Lower Columbia Basin, and Blue Mountain foothills. Ensemble are in fairly good agreement with the breezy regime Tuesday and Thursday, with differences related to overall strength and timing of the passing synoptic feature - with larger uncertainty present on Thursday. As a result, overall spread (25th-75th percentile) is 8-12 mph Tuesday and 10-15 mph Thursday. A Wind Advisory may be needed on either day, but current confidence of attaining wind gusts of 45 mph or greater is lacking as the NBM suggests there to be a 30-50% chance Tuesday and a 50-70% chance on Thursday of wind gusts reaching advisory criteria. 75

AVIATION...00Z TAFs...Most sites will be VFR through the rest of this TAF period, except KDLS/KYKM. KDLS may drop to MVFR as low clouds (1.5-2.5 kft) will arrive this evening along this upcoming system. KYKM remains LIFR due to lingering low clouds (300-2500 ft). However, KYKM should become VFR again around Sunday morning. Light rain will develop over KDLS/KPDT/KRDM/KBDN/KALW during this evening as well(<30% chance). In addition to that, KRDM/KBDN could also see sustained breezy winds up to 12kts with gusts at 20kts this afternoon with a 20-30% confidence on the extent. Feaster/97

PRELIMINARY POINT TEMPS/POPS

PDT 34 46 30 48 / 30 30 0 40 ALW 36 45 33 46 / 50 40 0 60 PSC 33 48 30 47 / 20 10 0 40 YKM 29 45 26 42 / 10 0 0 40 HRI 32 47 30 48 / 20 10 0 30 ELN 26 39 25 37 / 20 0 0 60 RDM 28 43 24 44 / 30 20 0 10 LGD 33 43 28 41 / 40 70 20 50 GCD 34 42 28 42 / 30 60 20 40 DLS 35 47 32 45 / 60 10 0 60

PDT WATCHES/WARNINGS/ADVISORIES

OR...Winter Storm Watch from late Monday night through Thursday afternoon for ORZ502-509.

WA...Winter Storm Watch from late Monday night through Thursday afternoon for WAZ030-522-523.