Monday March 26, 2018

Wednesday March 28, 2018
Tuesday March 27, 2018
Monday March 26, 2018
Confidence: High - Weather models in agreement and good field data

Main Concerns

Cornice Fall, Storm Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Travel in avalanche terrain is not recommended when the avalanche hazard is posted as high. Significant quantities of dense new snow are forecast to fall on a widespread weak layer from last weekend (surface hoar). Give avalanche paths and their runouts a wide berth as they have the potential to run further than one may expect during this forecast period even into paths that stretch down into lower elevation bands. Cornices will be additionally loaded and travel above and below then should be avoided. Dense low angled forests would be the place to be if you are heading out to play.

Avalanche Summary

Friday - Mt Washington avalanche control produced numerous soft slab avalanches up to size 1.5 on N-NE asp at treeline and below. Sunday - Ski cutting was still producing easy loose dry avalanches on steep N treeline terrain down approx 10 cm.

Avalanche Problems

Cornice Fall

Additional load from the coming warm storm (Monday into Tuesday) will apply more weight to already large and fragile cornice features. Triggering has the potential to happen naturally and is very likely with human activity. Give these monsters a wide berth, both on top of and below, as they have the bulk to produce avalanches up to size 2-3 on N-E asp in the alpine and treeline zones.

Storm Slab

Significant quantities of new snow will fall on a suspect weak layer (surface hoar). Strong winds from the SW and warming temperatures will accompany this storm, increase the avalanche hazard significantly. Expect avalanches hazard to exist on all aspect in the alpine, treeline and also open below treeline features (especially N-E asp and crossloaded features where wind loading magnifies quantities). Triggering is likely to initiate naturally and is very likely with human activity up to size 3.

Snowpack Summary

Cold new snow fell Friday. The weekend saw small amounts of new snow with some isolated convective activity producing some graupel. The big story was widespread surface hoar that developed over Saturday night and remained intact at the end of Sunday on all aspects at treeline and below. Early Monday morning the next snow fall began over the entire forecast region, with greater quantities falling to the north (Mt Cain region).

Snowpack Details

SurfaceNew snow over a suspected weak layer (surface hoar)
UpperRecent storm snow from last week, bonding moderate to the March 22 crust
MidWell settled
LowerWell Settled

Past Weather

Nice new snow for folks fell Friday. The Weekend was a mixed bag of conditions with a little bit of new snow, large temperature fluctuations between day and night (-8 to +3 at times) and even a little convective activity and graupel. Winds were general light to moderate form the SW.

Weather Forecast

Significant new snow fall (potential mixed precip at lower elevations) with warm temperatures and strong SW winds Monday into Tuesday.

Monday - 9 to 40 mm of new precip, winds moderate rising to strong SW, temps -3 to +2, freezing level 1200 rising to 2300 m overnight.

Tuesday - 6 to 17mm of new precip, winds strong SW dropping to light W, temps +2 dropping to -3, freezing level 2300 dropping to 1000m

Wednesday - trace to new new precip, winds light to moderate N-W, temps -1 to -6, freezing level 700 to 1000 m.

Posted on Monday March 26, 2018 by Bill Phipps

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