textproduct: Pendleton

AVIATION...06Z TAFS

VFR conditions currently across most sites, with the only exception being KDLS experiencing MVFR conditions due to reduced visibilities of 5SM. These conditions are expected to persist with light rain likely (60-70% chance) late in the period. This rain is a result of a lifting front from the south, which will also cause MVFR ceilings of 15-30kft beginning late afternoon at most sites. Light rain is also possible (~30%) for KRDM/KBDN early to mid-afternoon. The only terminal forecast to drop to IFR Tuesday evening will be KYKM due to reduced visibilities of 2SM. 75

PREV DISCUSSION

/issued 241 PM PST Mon Dec 22 2025/

KEY POINTS...

1. Widespread low elevation rain Tuesday afternoon through Wednesday morning

2. Mountain Pass Snow through Christmas Eve *SPS in affect*

3. Breezy winds Christmas eve *SPS in affect 1 AM through 4 PM Wednesday*

DISCUSSION...Current satellite shows partly sunny skies across portions of the CWA. Radar shows a few returns moving across Klickitat, Yakima, Benton and Franklin. Ground observations have recorded 0.01-0.04 inches of precipitation has fallen in the last 3 hours between Klickitat and Yakima counties.

Models show an active weather pattern with an associated atmospheric river (AR) is expected to impact the Cascades, most notably over the Washington Cascades. Moderate rain favored, with amounts between 0.5- 1 inch (60-80% confidence) at the Cascade crest with lesser amounts found at the lower elevations. Lower elevations will see up to 0.05 inches of rain overnight and again into Wednesday with 80-90% confidence. Models show the upper level low with the AR to move just enough to push the band of precipitation across the OR portions of the CWA moving form the southeast to the northwest before becoming mostly focused over the Cascades by Tuesday night.

Tonight snow levels will decrease to between 2000-3000 feet allowing for precipitation to transition over to snow along the Cascade Passes. Heaviest amounts of precipitation will be along the WA Cascades with 70-90% confidence in 2-3 inches of snow overnight. The OR Cascades will remain a little dryer with 50-60% confidence in 2-3 inches of snow overnight. Along the eastern mountains and the crests of the Blues will see light accumulations below 0.5 inches with 80% confidence. Even with the AR focused on the WA Cascades through Wednesday and Thursday, snow accumulation amounts will be near or slightly above and additional 2 inches each day (50-70% confidence) With that said, and SPS has been issued for snow accumulations along the passes as this is a high travel week and with many detours, the passes will see more than the usual holiday traffic.

Models show the upper level low to have an associated surface level low that will move into the region from the south and push off eastwards. Pressure gradient models show a tightening of the gradients of near 15 mb from central OR along the John-Day Ochoco Highlands and through the eastern mountains. This will lead to breezy conditions across the aforementioned areas. This surface low will bring southeast winds of 15 to 25 mph with gusts up to 30-35 mph expected (60-80% confidence). 90

PRELIMINARY POINT TEMPS/POPS

PDT 33 44 34 51 / 10 40 40 30 ALW 36 44 37 50 / 10 50 50 50 PSC 31 43 34 49 / 10 20 70 40 YKM 27 41 31 43 / 20 10 80 50 HRI 31 44 34 50 / 10 30 60 30 ELN 24 36 28 41 / 40 0 80 70 RDM 26 43 30 48 / 0 40 30 20 LGD 31 42 38 50 / 10 70 30 50 GCD 33 46 39 51 / 10 80 20 50 DLS 36 44 38 47 / 60 20 80 50

PDT WATCHES/WARNINGS/ADVISORIES

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