Monday February 19, 2018

Monday February 19, 2018
Tuesday February 20, 2018
Wednesday February 21, 2018
Confidence: High - forecast models, generally align

Main Concerns

Loose Dry, Wind Slab, Cornice Fall - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Utilize terrain to minimize exposure to recently loaded slopes and overhead hazard such as cornices.

Seek low angle terrain and areas shelter from the wind.

Avalanche Summary

Explosive avalanche control reports from Mount Washington on Sunday February 18 produced numerous results. On steep north aspect in areas protected from wind, ski cutting produced up to size 2 avalanches. Explosive avalanche control produced on north east aspects, avalanches up to size 2. All of the avalanches failed on the old melt freeze surface buried on February 14. These avalanches were primarily slab avalanches, however in a few spots , they were loose dry avalanches.

Avalanche Problems

Loose Dry

New low density will be slow to settle and bond over the forecast period due to cool temperatures . These avalanches are touchy to human triggers and when initiated, can begin as small but will gain mass and have the possibility of producing large avalanches , size two. Loose dry avalanches will be found in the alpine and tree line,on all aspects but only in areas not effect by wind.

Wind Slab

Winds slab will predominantly be found on lee aspect but will as well be found on cross loaded features that face the wind. Touchy to human triggers, these avalanches once initiated will produce large avalanches , size two.

Cornice Fall

Cornices are large and can be found on north aspects at both the treeline and the alpine. If triggered these could produce an avalanche big enough to bury injure or kill a traveler. Take the time to identify these features and ensure a wide berth when travelling either above or below them.

Snowpack Summary

Two snowfalls over the previous forecast period have buried any past exposed melt freeze crust. The new snow fell during cool temperatures and winds were moderate from both the north east and west. The upper snow pack is cold, light and dry. Moderate bonding has occurred at the melt freeze crust, however light snow has been continually transported and lee aspects/ south aspects have seen a rapid load over the last 48 hours creating a noted instability. Below the melt freeze crust and well settled and strong snow pack exists.

Snowpack Details

Surfacelow density, light and dry
Uppermelt freeze crust
Midwell settled
Lowerwell settled

Past Weather

Cool temperatures, moderate snowfall and north western wind rounded out the past weekend. Snowfall was light and dry with amounts any where from 20 cm to 55 cm.

Weather Forecast

Monday no new snowfall temps -15 to -4, winds moderate north west, freezing level 0 m rising to 300 m mid day.

Tuesday no new snowfall temps -12 rising to -6, winds moderate north west, freezing level 0 m rising to 200 m mid day.

Wednesday no new snowfall temps -14 to -5 winds light to moderate north west , freezing level 0 m rising to 300 m mid day.

Posted on Monday February 19, 2018 by Jesse Percival

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