Global Snow & Avalanche Outlook #3
EARLY DECEMBER 2025
A developing northern-hemisphere winter pattern is now sending storms into multiple ski regions at once — with Japan, Western Canada, the Alps, and parts of the US West all entering meaningful early-season cycles. The Himalaya remains comparatively dry under weak Western Disturbances.
NORTH AMERICA — UNITED STATES
Western US – Rockies & Intermountain
Observed Conditions
Early-December storms added 15–35 cm across central and northern Rockies, with pockets above 40 cm in the Tetons, Wasatch, and northern Colorado. Lower elevations remain thin, especially on south-facing slopes and wind-scoured ridges. Higher north aspects have the most continuity.
Forecast (Next 5–7 Days)
Another series of waves continues the storm cycle:
• Early–mid week: scattered light snow 2–8 cm.
• Thu–Fri: stronger shortwave bringing 8–20 cm, locally 30+ cm on high-elevation windward slopes.
• Weekend: lingering orographic snow with cold temperatures preserving quality.
Synoptic Pattern
A polar-vortex-displaced trough sits over the western US, sending repeated shortwaves into the Rockies with tightening NW flow late week.
Avalanche Scenario
Early-season structure remains fragile:
• Faceted basal layers under newer snow.
• Wind slabs on lee slopes and ridgelines.
• Small to medium slabs still consequential due to rocks.
• Trigger points likely on steep, unsupported convexities.
Western US – Sierra Nevada & Pacific Northwest
Observed Conditions
Sierra Nevada has seen trace–10 cm from weak systems. The Pacific Northwest gained 15–30 cm, especially at higher elevations. Lower slopes show crust layers from fluctuating snow levels.
Forecast (Next 5–7 Days)
• Light snow continues through mid-week.
• A stronger Pacific front Fri–Sat:
— Sierra: 10–25 cm above 2300–2500 m.
— PNW: 15–30 cm mid/upper mountain; locally higher on volcano flanks.
Snow levels drop as colder air moves in.
Synoptic Pattern
Maritime lows roll into the coast with post-frontal cold pools that improve snow quality inland.
Avalanche Scenario
• Wind slabs and storm slabs in the PNW where new snow overlays crusts.
• Sierra: sensitive soft slabs on crust layers, especially on steep terrain.
• Watch for rain/snow-line driven crust transitions.
Eastern US – Appalachians & Northeast
Observed Conditions
Interior Northeast (VT, ME, Adirondacks) recorded 10–25 cm through lake-effect and light synoptic events. Lower Appalachians remain mixed with intermittent freeze–thaw cycles.
Forecast (Next 5–7 Days)
A coastal low Tue–Wed may bring 10–25 cm to higher New England terrain, with mixed precipitation further south and upslope snow lingering after frontal passage.
Synoptic Pattern
Cold continental air interacts with a coastal cyclone, enhancing snowfall over interior high terrain.
Avalanche / Travel Scenario
True avalanche terrain is limited. Primary hazards: drifted wind pockets, crust formation, icy surface conditions, and access issues.
NORTH AMERICA — CANADA
Western Canada – Coast Mountains & Interior BC
Observed Conditions
Western Canada continues to outperform other zones this early season:
• Lake Louise: ~60/80 cm (lower/upper base) and ~75 cm recent storm snow.
• Interior BC ranges gained 20–50 cm over 1–2 weeks.
• Coastal mountains have strong upper-mountain coverage.
Forecast (Next 5–7 Days)
• Coast Mountains: 15–30 cm through multiple pulses.
• Interior BC: 20–40 cm, with high zones up to 40–50 cm+.
• Stronger system Thu–Sat provides the best powder window.
Synoptic Pattern
A persistent Pacific jet with cold air inland supports consistent orographic snow production.
Avalanche Scenario
• Widespread wind slabs in alpine zones.
• Storm slabs forming over older crust layers.
• Sensitive slabs likely for 24–72 hours after new loading events.
Canadian Rockies & Eastern Canada
Observed Conditions
• Rockies gained 10–25 cm recently but remain thin with faceted lower layers.
• Eastern Canada saw 20–40 cm from coastal systems and lake-effect snow.
Forecast (Next 5–7 Days)
• Rockies: light top-ups of 5–15 cm.
• Atlantic Canada: 10–30 cm Tue–Wed in exposed terrain.
Synoptic Pattern
Cold continental air dominates, limiting storm strength but supporting dry snow.
Avalanche Scenario
• Rockies: shallow faceted base = isolated but dangerous slabs.
• East: drifted pockets in limited avalanche terrain; main concerns remain travel hazards.
EUROPE — ALPS
French Alps
Observed Conditions
Storm cycles produced 80–100 cm in Haute-Savoie, creating excellent early-season coverage above 1800–2000 m. Upper glaciers exceed 150 cm snow depth. Lower slopes remain variable.
Forecast (Next 5–7 Days)
• Midweek: 5–10 cm showers.
• Weekend: stronger system delivering 20–40 cm at altitude; locally higher on NW-facing massifs.
Synoptic Pattern
Atlantic lows continue to push moisture into the western Alps under a disrupted polar vortex regime.
Avalanche Scenario
• Wind slabs above treeline.
• Persistent layers exist where snowpack is thinner.
• Temporary danger spikes after storm cycles.
Swiss Alps
Observed Conditions
Widespread 30–50 cm last week, with deeper pockets in northern and western sectors. Upper elevations commonly exceed 150 cm.
Forecast (Next 5–7 Days)
• Light snow Thu–Fri 5–15 cm.
• Weekend: 10–25 cm in stau regions.
Synoptic Pattern
Swiss Alps remain under an active frontal corridor with fluctuating winds.
Avalanche Scenario
• Moderate to locally Considerable danger.
• Wind slabs and persistent interfaces above ~2400 m remain critical.
Austrian & Italian Alps / Eastern Alps
Observed Conditions
Austria received 30–50 cm from recent storms, with Italy and Eastern Alps gaining 20–40 cm. High-elevation touring terrain is well-covered; mid/lower elevations remain mixed.
Forecast (Next 5–7 Days)
• Midweek: 5–15 cm.
• Late-week: 15–30 cm, with 30+ cm possible in northern stau zones.
Synoptic Pattern
Alternating warm and cold periods driven by Atlantic storm energy interacting with Alpine terrain.
Avalanche Scenario
• Wind slab + persistent slab combination remains dominant.
• Buried crust–facet layers still reactive on steep, unsupported terrain.
JAPAN — HOKKAIDO & HONSHU
Hokkaido
Observed Conditions
Snowfall has come in steady pulses of 10–20 cm, building a modest early-season base. Some resorts report ~15/45 cm lower/upper base. Coverage improves significantly above mid-mountain.
Forecast (Next 7 Days)
• Recurring snow showers: 15–30 cm midweek.
• Strong late-week front: 30–50 cm on W/NW-facing ranges.
• Weekly totals: 40–70 cm possible in coastal mountains.
Synoptic Pattern
Strong northwest monsoon drives cold Siberian air over the Sea of Japan, fueling convective and orographic snow bands.
Avalanche Scenario
• Wind slabs above treeline from sustained NW winds.
• Storm slabs forming on crusts and old surfaces.
• Tree-well and creek hazards remain significant where snowpack is thin.
Honshu (Hakuba, Myoko, Nozawa, Tohoku)
Observed Conditions
Early pulses dropped 10–30 cm across northern Honshu. Some upper-mountain areas already show 60–80+ cm from recent storms. Lower elevations remain thin but improving.
Forecast (Next 5–7 Days)
• Successive moisture bands: 40–60 cm widespread.
• Strong front late week: 80–100 cm possible in upper-mountain zones.
• Heaviest snow targets Hakuba–Myoko–Joetsu belt.
Synoptic Pattern
Persistent NW fetch over the Sea of Japan, amplified by a frontal zone mid–late week, creates ideal early-season snow mechanics.
Avalanche Scenario
• Rapid evolution from thin cover to full storm-slab hazard.
• Significant wind loading on alpine ridges.
• Gate and sidecountry access will adjust according to slab reactivity.
HIMALAYA — INDIA / NEPAL / PAKISTAN
Western Himalaya (J&K, Himachal, North Pakistan)
Observed Conditions
The past week remained mostly dry, with only isolated flurries at higher elevations. Snowpack is thin, discontinuous, and strongly elevation dependent across J&K, Ladakh, Lahaul–Spiti, and northern HP valleys.
Forecast (Next 7 Days)
• Weak Western Disturbance brings 5–15 cm above 3200–3800 m between 4–10 December.
• Snowfall will be scattered and light; no deep reset expected.
• Lower valleys remain dry and cold with inversions.
Synoptic Pattern
A shallow trough with limited moisture moves across northern India, producing only brief cloud/snow episodes.
Avalanche Scenario
• General hazard low to locally moderate.
• Wind slabs on high ridges after any light snow.
• Shallow snow over steep terrain can still release small slabs.
• Objective hazards (exposure, ice, rockfall) remain dominant.
Central & Eastern Himalaya (Uttarakhand, Nepal, Sikkim)
Observed Conditions
Mostly dry. High peaks retain old autumn snow while mid-level terrain remains in late-autumn condition.
Forecast (Next 7 Days)
Dry for most of the region, with only trace snow possible on extreme high summits. Cold nights and occasional valley fog are expected.
Synoptic Pattern
A stable ridge dominates, preventing stronger winter systems from penetrating eastward.
Avalanche Scenario
Very low avalanche hazard, except on steep, icy, glaciated high terrain. No storm-snow issues until larger Western Disturbances arrive later in winter.
SUMMARY
North America: Western Canada, PNW, and Interior BC lead with the strongest storm cycle and 20–60+ cm incoming. US Rockies slowly accumulate with 5–25 cm expected. East sees mixed snow but limited avy terrain.
Alps: Strong early-season base, another 20–40 cm this week, but wind slabs and persistent weak layers keep danger fluctuating.
Japan: The standout zone globally. Hokkaido may take 40–70 cm this week; Honshu may see 40–60 cm widely and up to 80–100 cm in upper mountains. Avalanche risk will rise sharply.
Himalaya: Mostly dry under a weak WD. Light snow 5–15 cm limited to high passes. Avalanche activity is minimal but terrain hazards remain.
Winter is building momentum globally — but local avalanche conditions are volatile. Stay updated and stay safe.
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