Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Sun
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Be weary of the larger snow drifts found in east facing ravines until stability can be determined. Use caution in steep terrain, where falls are dangerous on a refrozen snowpack with exposed rocks, ice, and trees below.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    Prior to the snow and rain over the last 32 hours, isolated pockets of 6-24 inch thick wind slabs on top of a strong melt freeze crust were found at middle and upper elevations. In many locations these slabs were proven to be poorly bonded to the melt freeze crust below. 

    The possibility exists that the thick wind slabs may still harbor dry snow at the interface between the snow and the January 5th melt-freeze crust. If a weak layer remains, so does the chance for triggering one of these slabs. While unlikely, don’t take a chance: dig down through the new snow, past the old snow and look for dry snow above the melt freeze crust. If you find soft dry snow, that will be your target to watch for as you make your stability assessments before committing to the slope. 

    Areas with the greatest concern are the east-facing gullies at middle elevations. Left Gully and Chute in Tuckerman Ravine, Central Gully in Huntington Ravine harbored the thickest known pockets of wind slabs.

Avalanche Discussion

How did we get here?

Thursday: Around 5 inches of snow fell late overnight Thursday and into Friday morning. This new snow landed on top of a mix of widespread melt freeze crust and areas of wind slab, some up to 24 inches thick in east facing ravines. These slabs were reactive to triggering for several days last week leading into the recent winter storm. 

There’s a chance that the snow was transported by south winds, creating new wind slabs at middle and upper elevations. However due to the light wind speeds, less productive fetch and wet snow from warming temperatures - any new slabs are likely to be thin and easily settled by rain following the snow. 

Friday: Warm temperatures turned remaining precipitation to freezing rain and rain with a SWE of 0.61 inches. This rain soaked into the snowpack likely working to settle and stabilize the snowpack. 

The question for today, is did the rain soak through the new and old snow to stabilize the weak layer found in the old wind slabs? Are old wind slabs still reactive? It is unlikely, but shouldn’t be ruled out until proven otherwise. 

The Lion Head Summer Trail is OPEN due to reduced avalanche risk, and is currently the least hazardous, direct route to the summit of Mt Washington from Pinkham Notch. 

OBSERVATIONS: Please consider submitting an observation of what you are seeing in your travels. Submitting an observation hones your skills, informs other users, and improves our forecasts. 

Regioni coperte