Global Snow & Avalanche Outlook #5

Issued: 21 December 2025 (covering the next ~7 days)

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1) North America — USA

Pacific Northwest & Washington/Oregon Cascades — “AR conveyor belt + high elevation snow”

Observed (last week)

• Multiple rounds of strong wind and precipitation in the coastal ranges and Cascades—classic “wet everywhere, snow in the upper mountain” pattern.
• Wind has been a major story: widespread transport at middle/upper elevations → rapid drift formation.

Forecast (next ~7 days)

• Pacific jet remains active with additional moisture surges. Expect continued loading at elevation with snow levels fluctuating (snow-to-rain line will be the whole game).
• When colder air is in place: moderate to heavy mountain snowfall possible—especially favored on the Olympics and WA Cascades during stronger pulses.

Avalanche scenario

• Primary problems: wind slabs (stiff, reactive) at mid/upper elevations; storm slabs where new snow stacks quickly.
• Key terrain: lee features near ridgelines, cross-loaded gullies, unsupported rollovers above treeline.
• Expect danger to ratchet up during/just after the bigger pulses; give the snowpack time to settle if you’re stepping into bigger alpine lines. (NWAC)

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Sierra Nevada (Northern/Central) — “Atmospheric rivers + big alpine snow potential”

Observed (last week)

• A sharp pattern change: a stormy West Coast regime re-established with multiple moisture events lining up.

Forecast (next ~7 days)

• Multi-day storm window with significant high-elevation snowfall potential during the stronger AR phases.
• NWS messaging has already moved into Winter Storm Watch territory for parts of the Sierra—this is usually a “don’t treat totals lightly” signal even before exact numbers are locked. (NWS Sacramento)
• Expect the “where it’s snow vs rain” cutoff to shift—final snow totals will be altitude dependent.

Avalanche scenario

• Primary problems: storm slabs during rapid accumulation; wind slabs near ridgelines when the gradient tightens; and in the big AR pulses, watch for upside-down density changes (heavier snow on lighter snow).
• Operational takeaway: plan conservative travel during the most intense precipitation + wind windows, then reassess once the storm cycle pauses.

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Wasatch (Utah) — “Thin structure + stubborn weak layers”

Observed (last week)

• Generally a structure-driven season start: faceting/weakness in the snowpack is the headline more than huge snowfall totals.

Forecast (next ~7 days)

• No sustained deep reload implied right now; focus is on smaller events and wind periods that can still build slabs efficiently.

Avalanche scenario

• Primary problems: persistent slabs in the structure (where slabs exist), plus wind drifts near ridges even with modest snowfall.
• Consequence note: early season persistent problems = “low probability / high consequence” in the wrong terrain. (Utah Avalanche Center)

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Tetons (Wyoming) — “Wind slab factory with intermittent reloads”

Observed (last week)

• Wind + variable snow has been shaping the hazard: slabs in the alpine are the recurring theme.

Forecast (next ~7 days)

• Look for opportunities for new snow + wind combinations—classic Teton hazard accelerant even without blockbuster totals.

Avalanche scenario

• Primary problems: wind slabs; lingering persistent weaknesses depending on elevation band and where slabs have formed.
• Where it bites: alpine bowls, lee-loaded convexities, and cross-loaded couloirs. (Bridger-Teton Avalanche Center)

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Colorado (Front Range / Central Mountains) — “Persistent weak layer country”

Observed (last week)

• Classic Colorado early season: facets/persistent weak layers are widespread—this is the “don’t trust the first good-looking slab” phase.

Forecast (next ~7 days)

• Even modest snow (10–25 cm type events) plus wind can be enough to build cohesive slabs over weak snow.

Avalanche scenario

• Primary problems: persistent slabs (the main one), plus new wind slabs during transport periods.
• Decision framework: treat steep unsupported terrain as “high consequence” until the structure proves otherwise. (CAIC)

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2) North America — Canada

South Coast / Sea-to-Sky / Coast Mountains — “Storm slab + wind slab management”

Observed (last week)

• Coastal pattern has been active: repeated precipitation + wind cycles → the hazard is less about one storm and more about cumulative loading.

Forecast (next ~7 days)

• Additional storms expected with continued periods of wind—good for building snowpack depth, bad for rapid instability when it comes in hot.

Avalanche scenario

• Primary problems: storm slabs during active snowfall; wind slabs where ridgelines get hammered; watch for bonding issues at interfaces between pulses. (Avalanche Canada)

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Interior BC (Selkirks/Monashees) & Canadian Rockies — “Early season depth, but don’t mistake depth for stability”

Observed (last week)

• Many zones have a “strong start” feel—more snow on the ground than average for this time in some areas, but wind has been actively shaping slabs.

Forecast (next ~7 days)

• Further accumulation is on the table with additional systems and transport periods.

Avalanche scenario

• Primary problems: wind slabs + storm slabs; plus any lurking persistent layers depending on the local early-season crust/facet history.
• Field habit: treat post-storm days as “stabilization days,” especially if you’re stepping into bigger alpine terrain. (Avalanche Canada)

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3) Europe — Alps

Switzerland — “Low overall snow depth, localized drifted slabs, and small wet activity where sun/temps act”

Observed (last week)

• Snow cover remains below seasonal in many areas; wind-affected slabs exist in pockets rather than blanket coverage.

Forecast (next ~7 days)

• No broad “reset dump” implied in the official hazard messaging right now; watch for incremental snow + wind events that build new slabs over weak snow surfaces.

Avalanche scenario

• SLF currently emphasizes drifted snow and old snow weaknesses in places, with generally Moderate (Level 2) hazard in listed regions and caution around drifted deposits. (SLF / WhiteRisk)
• Also noted: where the cover is thin, the fall/drag hazard (rocks, discontinuous base) is a real consequence multiplier even if avalanches are small.

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French Alps (Alps du Nord / Alps du Sud) — “Wind transport + elevation-dependent snow lines”

Observed (last week)

• Typical early season pattern: variable coverage, with wind shaping the upper mountain and lower elevations sensitive to rain/snow fluctuations.

Forecast (next ~7 days)

• Météo-France mountain products highlight ongoing winter weather signals with snow levels moving—expect conditions to be highly altitude-dependent.

Avalanche scenario

• Use the Météo-France “risque avalanche” mountain pages as your baseline: when wind + new snow coincide, drifted slabs become the practical problem to manage. (Météo-France Montagne)

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4) Japan — Hokkaido & Honshu

Big picture — “Winter monsoon (NW flow) still firing”

Observed (last week)

• Northern Japan has seen real winter conditions, including disruptive blizzard episodes in Hokkaido/Tohoku with strong winds and rapid snowfall bursts.
• Public reporting tied to JMA messaging has referenced up to ~40 cm in 24 hours in parts of Hokkaido during a recent event window. (JMA via public reporting)

Forecast (next ~7 days)

• Use JMA’s public snow analysis/forecast products to track the next pulses: the setup remains favorable for recurring snowfall on the Sea-of-Japan side when cold air outbreaks align with moisture fetch. (JMA “Analysis and Forecasts of Snow”)
• Expect classic banding/orographic enhancement: totals vary sharply over short distances depending on wind direction and convergence.

Avalanche scenario

• Primary problems: rapid storm-slab development during high-rate snowfall; wind slabs above treeline when NW winds accelerate; and fast bonding transitions on buried crusts/old surfaces early season.
• Operational reality: “thin-to-loaded” transitions can happen quickly in Japanese alpine bowls—manage slope scale, avoid being early to steep convexities right after the heaviest bands.

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5) Himalaya — India / Nepal / Pakistan

Western Himalaya (J&K / Himachal / Northern Pakistan) — “Still mostly a quiet start, but winter travel friction rising”

Observed (last week)

• Conditions remain generally “thin/patchy” in many zones, with non-snow hazards (cold, wind, and travel disruption) often dominating the practical picture.
• IMD has continued public warnings around winter disruption signals: fog/cold wave impacts in the plains and fresh snowfall potential in the western Himalaya that affects passes/road travel windows. (IMD via public reporting)

Forecast (next ~7 days)

• Look for light to locally moderate high-elevation snowfall windows tied to western disturbances; the key is whether a disturbance slows enough to produce meaningful totals or just “decorates the upper mountain.”

Avalanche scenario

• Most zones: hazard is likely localized rather than widespread—watch for isolated wind slabs above ~treeline where there’s enough snow to transport.
• Big practical warning: thin snow cover = high consequence for falls/rocks; even small slabs can push you into terrain traps.

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Hemispheric Pattern Check (why this all hangs together)

• AER’s AO/PV discussion continues to emphasize a “rinse-lather-repeat” style winter circulation with cold largely favoring higher latitudes at times, plus periodic stretched-PV episodes that can shove cold/snow windows into the East/Maritimes and parts of Asia/Europe depending on week-to-week ridge placement. (AER AO/PV Blog)

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Bottom Line (actionable takeaways)

• PNW + Coast Mountains: active jet + moisture = loading cycles. Avalanche problem is not subtle: storm slabs + wind slabs.
• Sierra: watch the snow line and timing of the strongest AR pulses—high-elevation snow potential is meaningful; expect rapid hazard rises during peak rates.
• Intermountain (Wasatch/Tetons/Colorado): structure matters more than totals—persistent problems can make “normal” storms feel abnormal.
• Alps: generally modest snow cover in many areas; drifted snow and consequence management are key; don’t let “Moderate” lull you in thin/rocky terrain.
• Japan: the most consistently wintery signal right now—NW monsoon pattern supports frequent snow; wind + rapid loading means fast-evolving slab conditions.
• Himalaya: still not in full winter mode everywhere; travel/weather disruption may be a bigger limiter than deep snow—watch for WD windows and isolated slab formation at altitude.

Safety note: This is a planning-level synthesis, not a substitute for local bulletins and field observations.