Typical operating window
December–AprilEarly-winter Pacific storms usually establish the operating base before the main January–March period.Verified planning context
Snow, weather and avalanche context
Historical patterns help you compare trips. They do not predict your week or replace the operator's daily decisions.
Strongest comparable snow evidence
1,910 mm SWE median · 1,418–2,169 mm interquartile rangeOrchid Lake snow courseTier B · observed reference · moderate confidenceSnow character
transitionalThe interior often combines reliable snowfall with colder surface snow, but persistent weak layers can develop during dry cold spells.Public avalanche information
Avalanche Canada regional forecast mapPublic coverage is regional. Operators use site-specific observations and professional forecasting.Weather and flight context
Moist systems weaken inland and interact with successive mountain ranges, causing sharp local snowfall differences.
- Valley inversion
- Orographic cloud
- Ridge wind and cold
Meteorological reference area
Interior British Columbia catalogue subregions
- Includes
- Two published subregions, evaluated separately before aggregation.
- Excludes
- Northern, eastern, and Bella Coola profiles.
- Elevation
- No verified operator-terrain elevation band is public. Each evidence value retains its site elevation.
Evidence pack
Measurements, claims and gaps stay separate.
Tier BSouthern subregion peak SWE reference1,910 mm SWE median · 1,418–2,169 mm interquartile range
- Site
- Orchid Lake snow course · 49.5333, -123.0500 · 1190 m · 20 km from the catalogue reference
- Period
- 1991/92–2014/15 complete snow seasons within the 1991–2016 archive
- Completeness
- 24 seasons with at least two valid observations; 166 observations used.
- Method
- Maximum SWE by October–September snow season; median and quartiles across valid seasons.
- Limitation
- This coastal reference must not be combined with the northern subregion as one terrain value.
- Canadian Historical Snow Survey DataEnvironment and Climate Change Canada · accessed 2026-08-25
Tier BNorthern subregion peak SWE reference836 mm SWE median · 690–1,018 mm interquartile range
- Site
- Downton Lake Upper snow course · 50.8667, -123.1833 · 1890 m · 30 km from the catalogue reference
- Period
- 1994/95–2014/15 complete snow seasons within the 1991–2016 archive
- Completeness
- 21 seasons with at least two valid observations; 93 observations used.
- Method
- Maximum SWE by October–September snow season; median and quartiles across valid seasons.
- Limitation
- This site represents only the northern catalogue subregion.
- Canadian Historical Snow Survey DataEnvironment and Climate Change Canada · accessed 2026-08-25
Tier CModelled snowfall water equivalent — Northern catalogue location603 mm SWE median · 544–670 mm interquartile range
- Site
- Northern catalogue location ERA5-Land grid cell · 51.0000, -122.8000 · 5.7 km from Northern catalogue location reference point
- Period
- Calendar years 1991–2020
- Completeness
- 360 monthly means; all 30 calendar years contain 12 values.
- Method
- ERA5-Land monthly mean daily snowfall accumulation was multiplied by calendar days and 1,000, then summed by calendar year.
- Limitation
- This reference area supports evidence discovery and comparison. It is not an operating-area or tenure boundary. This unadjusted 0.1° reanalysis grid cell is not an observation, snow depth, or terrain-wide total. Grid elevation and wind redistribution can cause substantial local bias.
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
Tier CModelled snowfall water equivalent — Southern catalogue location1,349 mm SWE median · 1,121–1,525 mm interquartile range
- Site
- Southern catalogue location ERA5-Land grid cell · 49.7000, -123.2000 · 3.3 km from Southern catalogue location reference point
- Period
- Calendar years 1991–2020
- Completeness
- 360 monthly means; all 30 calendar years contain 12 values.
- Method
- ERA5-Land monthly mean daily snowfall accumulation was multiplied by calendar days and 1,000, then summed by calendar year.
- Limitation
- This reference area supports evidence discovery and comparison. It is not an operating-area or tenure boundary. This unadjusted 0.1° reanalysis grid cell is not an observation, snow depth, or terrain-wide total. Grid elevation and wind redistribution can cause substantial local bias.
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
Monthly evidence
Each cell keeps its measurement type and unit. Reanalysis water equivalent is not snow depth. Text-only cells preserve a representative data gap.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 93.5 mm SWE | 50 mm SWE | 69.9 mm SWE | 52.4 mm SWE | 24.2 mm SWE | 9.9 mm SWE | 0.4 mm SWE | 0.3 mm SWE | 17.2 mm SWE | 66.3 mm SWE | 99.9 mm SWE | 85.3 mm SWE |
Commercial operator assessment
Operator assessment process not independently verifiedThe operator must assess current snow, avalanche terrain, weather, aircraft limits, and rescue options. No private operational plan is inferred.
Sources and evidence notes
- WMO Climatological NormalsWorld Meteorological Organization · accessed 2026-08-25
- ERA5-Land hourly data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-25
- Historical Climate DataEnvironment and Climate Change Canada · accessed 2026-08-25
- Published operator and trip inventoryHeliski International editorial team · accessed 2026-08-25
- Canadian Historical Snow Survey DataEnvironment and Climate Change Canada · accessed 2026-08-25
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
- Avalanche Canada forecast mapAvalanche Canada · accessed 2026-08-25