Avalanche Forecast
Issued: Jan 20th, 2020 1:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices, Loose Wet, Wind Slabs and Storm Slabs.
Jesse Percival,
VIAC
Explosive avalanche control results at Tree line on Mount Washington produced on North thru to West aspects numerous size 1 and a few size 1.5 and 2 all slab. No other observations or reports.
Summary
Past Weather
Cool temps, snowfall between 40 to 50 cm on the eastern edge of the island range and over 110 mm reported on the westerner leading edge of the range. Strong south wind persisted over the entire forecast region during the previous forecast period.
Weather Forecast
Out with the cold, here comes the warmth. As a more typical south western flow will be the predominate weather feature in our forecast region. Expect continued winter storms to deliver moderate precipitation amounts with above seasonal average freezing levels. Monday 20 mm of precipitation , Winds moderate to strong from the South east, Freezing levels 1400 meters. Tuesday 30 cm of snow , Winds moderate to strong from the South east, Freezing levels 1000 meters.Wednesday 30 cm of snow , Winds moderate to strong from the South east, Freezing level 100 meters.
Terrain Advice
Give Cornice features a large berth when travelling both below or above them.Cautious, Conservative and Selective terrain management must be practiced when entering Steep, Unsupported and Wind loaded features. Choose low angle terrain during storm events and avoid areas with overhead hazard.During periods of high hazard, travel in avalanche terrain is not recommended.
Snowpack Summary
50 cm of storm snow now covers a variety of surfaces and has been reported to be currently bonding moderately well. The new storm snow has been transported by the strong south winds and deposited this new storm snow on lee aspects (North) forming wind slab and building cornices. Temperatures have began to warm and new precipitation below 1400 meters is falling as rain creating an unconsolidated upper snow pack.The mid pack has a variety of melt freeze crust with one being extremely robust and having the ability to bridge the lower snow packThe lower snow pack is well settled and dense, with the exception of the alpine where a deep an nonreactive basal instability is possibly still lurking.
Snowpack Details
- Surface: A variety of surface conditions dependent on elevation and what form the precipitation fell as
- Upper: 50 centimeters of storm snow that is setting rapidly
- Mid: A variety of melt freeze crusts can be found with the possibility of buried surface hoar still being found.
- Lower: Well settled and dense, with the exception of the alpine where a deep an nonreactive basal instability is possibly still lurking.
Confidence
Moderate - forecast models agree on precipitation amounts, with some discrepancy as to how high the freezing levels may rise.
Problems
Cornices
Touchy cornice features have been building and will be predominantly found on North aspects. Found in both alpine and treeline terrain, triggering of this avalanche problem is likely to very likely from light loads such as skiers. If triggered expect these avalanches to be large, up to size two or greater. Natural avalanches are possible to likely and may be certain at lower elevations with the input of rain.
Likelihood
Expected Size
Loose Wet
Warming temperatures and precipitation in the form of rain has unconsolidated the upper snow pack allowing for loose wet avalanches to become touchy to light triggers. Found on all aspects but specific to lower alpine elevations and below. During warming cycles expect triggering of this avalanche problem to be near certain from light loads such as skiers. If triggered expect these avalanches to start small but when they gain mass up-to size 2. Expect terrain features that are steep and gully like to promote the loose wet avalanche problem to gain mass and speed. Natural avalanches are very likely to certain.
Likelihood
Expected Size
Wind Slabs
New storm snow and strong winds have transported low density snow to all north aspects promoting the development of wind slab. Expect this avalanche problem to be touchy to light triggered especially with forecast wind and precipitation. Triggering of this avalanche problem is likely to very likely and when triggered will produce large up to size two avalanches. Natural avalanches are possible to likely.
Likelihood
Expected Size
Storm Slabs
Past snowfall and warming temperatures have begun to rapidly settle the current storm slab. Expect this problem, to be touchy to light loads such as skiers and will be found on all aspect. Found at all elevations, triggering of this avalanche problem is likely to very likely from light loads such as skiers. If triggered expect these avalanches to be large, up to size two and on specific terrain features very large, size 3. Natural avalanches are possible to likely.
Likelihood
Expected Size
Valid until: Jan 21st, 2020 1:00AM
