Weather
A stormy, wind-whipped week is on tap for the Pacific Northwest, with a warm start that favors heavier, wetter snow at lower elevations before a powerful midweek cold front drops snow levels to the passes and kicks off the deepest mountain totals, followed by a warmer late-week pulse that turns snow dense again before cooler, showery snow closes out the period. Snow levels start out quite high for mid-December, then crash to around 2,000–2,500 feet midweek before wobbling back upward again late week. The biggest overall snowfall favors the North Cascades, while the Oregon Cascades see more volatility in snow levels and quality, plus some very strong ridge winds. Expect frequent visibility and comfort challenges during the windiest windows, with snow quality improving notably once the colder air settles in mid to late week.
Monday night into Tuesday starts relatively warm, with snow levels hovering high enough that lower and mid elevations in the Cascades can skew toward wetter snow or mixed precipitation while the highest terrain collects modest accumulation. Snow levels during this opening phase are generally elevated, around 3,000–6,400 feet in the Washington Cascades and rising toward roughly 6,000–9,000 feet at times farther south, so lower elevations are most prone to dense snow near the rain line. Snow-to-liquid ratios also reflect that warmth, with many sites running in the 5–10:1 range, so early snow is heavy and upside-down where temperatures flirt with the freezing mark. Winds remain a key factor early, especially along exposed ridgelines, setting the stage for a more impactful transition as the next system arrives.
Tuesday night into Wednesday is the main event, featuring a sharp cool-down, rapidly lowering snow levels to around pass elevation, and a surge of heavy mountain snowfall that is accompanied by very strong winds on the Cascade crest. Snow levels plunge quickly, dropping to roughly 2,000–2,500 feet by Wednesday in many areas, which flips the mountains solidly into all-snow and drives the best storm totals in the North Cascades and along the Washington Cascade crest. This is also the windiest stretch for many higher elevations, so expect periods where exposed terrain feels downright rowdy. Snow quality is mixed early in the storm with SLRs near 6–10:1, but trends better behind the front, with many periods climbing into the 11–14:1 range for a more wintry, chalky-to-fluffy feel by later Wednesday into Friday. Where operations are open, Whistler should see a meaningful refresh with improving quality later in the week as snow levels dip to around 500–900 feet and SLRs push into the 14–15:1 range.
Thursday into early Friday brings another moisture push that favors heavier precipitation but also drives snow levels back upward at times, especially across the Oregon Cascades, keeping the snow denser and more variable by elevation. In the Oregon Cascades, snow levels can surge back up into the 5,800–7,600 foot range during the warmest part of this window, which is when the snow turns notably wetter and heavier at mid-mountain and below. After that, cooler air and lighter, more showery snowfall returns later Friday into Saturday, with snow levels settling back down closer to roughly 2,400–3,900 feet and SLRs rebounding toward fair-to-good quality. Looking beyond this window, the pattern favors continued active moisture into late December across Washington and Oregon, with additional storm chances and above-normal precipitation overall, while temperatures lean mild enough at times to keep snow levels fluctuating rather than locked low for extended stretches.
Resort Forecast Totals
- Mt Baker – 43″–64″ Mon night (12/15) – Sat (12/20)
- Stevens Pass – 39″–57″ Mon night (12/15) – Sat (12/20)
- Timberline – 37″–56″ total (4″–5″ Mon night (12/15) – Tue (12/16) + 33″–52″ Tue night (12/16) – Sat (12/20))
- Crystal Mountain – 30″–45″ Mon night (12/15) – Sat (12/20)
- Whistler – 27″–40″ Mon night (12/15) – Sat (12/20)
- Snoqualmie Pass – 22″–34″ Tue night (12/16) – Sat (12/20)
- Mt Bachelor – 17″–26″ Tue night (12/16) – Sat (12/20)
