Monday March 8, 2021

Wednesday March 10, 2021
Tuesday March 9, 2021
Monday March 8, 2021
Confidence: Moderate - Forecaster field observations and numerous reports. No alpine observation, uncertainty with alpine windslab stability .

Main Concerns

Loose Wet, Wind Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Caution when transitioning into terrain with recent wind loading and steep convex roll features.

Avoid direct solar terrain during periods of sunshine and daytime warming.

Caution above or below cornice features, recent loading has continued to build upon already very large cornices.

Avalanche Summary

On Friday, North aspect terrain produced two natural size three windslab avalanches between 1300 and 1500 meters. Avalanche control teams at Mount Washington utilized explosives to trigger numerous size 2 windslab avalanches. Skier trigger size 1 windslab avalanches continued to linger and reported on north west facing terrain just below 1300 meters on Sunday.

Avalanche Problems

Loose Wet

Clear sky and sun will cause the surface snow to become unconsolidated.

Location: Specific to steep Solar aspect terrain and at all elevations.

Possibility: Triggering of this avalanche problem from light loads such as skiers is likely to very likely. Natural avalanches are likely.

Size: If triggered, expect these avalanches to be small size 1 but could gain mass and push a traveler into a terrain trap.

Wind Slab

Found on predominantly North aspects. This avalanche problem was formed during the past storms strong south west winds. Caution on freshly loaded slopes, this problem if triggered has the potential to create very large avalanches.

Location: North East thru to North West aspects and found in both the Alpine and Tree line.

Possibility: Triggering of this avalanche problem is possible from light loads such as skiers. Natural avalanches are unlikely.

Size: If triggered expect these avalanches to be large size 2, and on isolated terrain features very large, size 3 .

Snowpack Summary

Storm snow amounts between 80 to 150 centimeters has been transported by the wind and can be found on North west thru to North east aspects. This new load of snow has begun to settle and overlies a previous crust surface and has either naturally released during the storm event or is moderately bonding. Terrain exposed to the wind is stripped and scoured. The persistent slab from February is now down over 200 centimeters and is dormant and currently non reactive to testing . Below the snowpack is dense and well settled.

Snowpack Details

SurfaceA variety of surfaces, new low density snow, wind scoured at upper ridge tops and wind loaded on north aspects.
UpperSettling new snow between 100 and 150 centimeters.
MidOld unreactive crusts, overall dense and well settled.
LowerWell settled and dense.

Past Weather

A significant storm event delivered on average over 100 centimeters of snow combined with strong South west wind. The western leading edge of the island mountains received over 150cm of new snow. Temperatures remained cool with freezing levels reaching 1200 meters but mostly stayed below 1000 meters.

Weather Forecast

Initially unsettled weather will bring clouds and light snowfall. By Tuesday evening a ridge of high pressure will bring clear sky and no new precipitation.

Monday: 1 to 5 cm , Winds Moderate from the South East, Freezing levels at 500 meters rising to 600 meters.

Tuesday: Trace amounts of snow, Winds light to moderate from the South East, Freezing levels at sea level with a day time high of 600 meters.

Wednesday: No new precipitation , Winds Light to Moderate from the North West, Freezing levels at seas level with a daytime a high of 1000 meters.

Posted on Monday March 8, 2021 by Jesse Percival

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