Avalanche Forecast

Issued: Jan 17th, 2017 3:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Loose Wet.

mgrist, Avalanche Canada

South Coast Inland.

Big changes are hard on the snowpack and can give surprising results. It's time to rein in your terrain use and stick to low consequence areas. If the Duffey zone sees >30cm snow on Tuesday - Wednesday, the danger rating will be HIGH.

Summary

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

We're in an active weather pattern with lots of uncertainty with regard to freezing levels and snow amounts. WEDNESDAY: 15-30 cm (wet) snow (or rain in the south). Freezing levels 1500m and alpine temperatures near -1 in the north (Duffey Lake road) ; Freezing levels 1900m and alpine temperatures to +3 in the south (Coquihalla). Winds moderate gusting strong (40-60 Km/hr) from the southwest. THURSDAY: Flurries (up to 5 cm) ending in the afternoon. Winds easing to moderate from the southwest. Freezing level 1300m and alpine high temperatures to -2 Celsius. FRIDAY: Scattered flurries with some sunny breaks. Freezing levels 1200m and alpine temperatures near -4 in the north and -2 in the south. Winds moderate gusting strong (40-60 Km/hr) from the southwest.

Avalanche Summary

Limited observations but no new reported. I expect a widespread cycle is imminent starting Tuesday.

Snowpack Summary

Sunday night into Monday defied the forecasts and we had a huge snowfall gradient across the region: Manning got 0cm ; the Coquihalla got 12mm rain ; the Duffey got 35cm snow and to cap it off Tenquille Lake got 50cm snow! This new precipitation fell on a wide variety of surface snow conditions:IN THE SOUTH (COQUIHALLA): There was a widespread melt-freeze crust up to 1650m (which probably got soaked with rain). From ridge top down to 1700m there are multiple wind slab layers on southerly aspects from the arctic outbreak events in December & January. These lingering wind slabs will likely remain reactive with the incoming precipitation (whether it falls as rain or snow) so use extra caution in your terrain choice. IN THE NORTH (DUFFEY LAKE RD): The melt-freeze crust from the weekend was limited to steep solar (south) aspects. Wind slabs were found on a variety of aspects (primarily southerly) as far down as 1850m. All the new snow (35cm+) in this zone is not expected to bond well to the old snow interfaces.

Problems

Storm Slabs

Storm slabs will remain touchy throughout the forecast period. Conservative terrain use is essential!

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

Where freezing levels are high and precipitation falls as rain, watch out for loose wet (slushy) snow, especially near gully and cliff features.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 18th, 2017 2:00PM