Avalanche Forecast
Issued: Apr 9th, 2021 2:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices, Wind Slabs and Storm Slabs.
Jesse Percival,
VIAC
A few loose wet avalanches up to size 2 less than 48 hours old were observed on steep South east aspects at 1400 meters.
Glide slab activity is evident on steep rock features with some buckling and cracking occurring. Previous Glide slab avalanche activity was observed but time line is unknow. These old glide slab avalanches were observed on very steep unsupported terrain at 1300 meters on an east aspect.
A few audible avalanches were heard Thursday coming from a large and steep slope facing directly south east and bathed in sun.
Summary
Past Weather
On Wednesday between 5 and 15cm of new snow fell 5 in the south with the northern and western ones seeing 15. This was followed by warming and rapid settlement of this new snow. Winds from the south west continued during the snowfall. Following this event, the daytime temperatures above 1500 meters rose above zero with freezing levels reaching 1800 meters. Overnight cooling was in full effect, and this promoted a supportive melt freeze crust.
Weather Forecast
A strengthening low pressure from the north will provide the last breathe of winter to our island forecast area. Precipitation amount vary through the region with the western and northerner zones receiving the high end of the precipitation amounts. Winds however are forecast to be strong from the south west over the entire forecast area. In the wake of this storm a high pressure will be the dominate feature and its likely to entrench for the entirety of next week with freezing levels by mid week soaring to the 3000 meter mark. Friday: 20-30 cm of new snow. Winds Strong from the Southwest, Freezing levels 500 meters rising to 900 meters. Temps at 1500 meters -4Saturday: 5 to 10 cm of new snow, Winds Moderate from the West , Freezing level 200 meters rising to 800 meters. Temps at 1500 meters -4Sunday: Trace amounts of snow. Winds variable and light, Freezing levels 100 to 1000 meters. Temps at 1500 meters -3
Terrain Advice
**Please respect the current closures at Mount Washington, no access is permitted at anytime on the ski areas slopes or terrain.** Avalanche danger ratings reflect the highest danger level expected over the course of the day.Caution when transitioning into freshly wind loaded slopes.Avoid travelling both above and below cornices.During periods of intense warming and sunshine avoid solar aspect terrain.
Snowpack Summary
Snowpack surfaces are predominantly settled and in most areas, formed a melt freeze crust. Snow surfaces are a mix of a near impenetrable crusts and on protected North aspects above 1800 meters, some preserved snow exists. On all aspects the surfaces Tree line and below have firmed up today and with the forecast new snow arriving tomorrow, expect sensitive storm slabs and wind slabs to be widespread. Mid and lower snowpack is well settled and dense.
Snowpack Details
- Surface: Variable surface conditions, dependent of elevation and orientation.
- Upper: Reactive crusts at 30cm and 100 cm
- Mid: Well settled and dense.
- Lower: Well settled and dense.
Confidence
Moderate - Field observations support current snowpack description and avalanche summary. Weather forecast models are well aligned.
Problems
Cornices
Cornices are widespread and large. Previous warming and cooling may have added some temporary strength, This problem will persist through the remainder of the season and can be both a trigger for slopes below as well are large enough to create an avalanche hazard alone.
**Location:** Predominantly north aspects at ridge top in the Alpine and Tree line.
**Possibility:** Triggering of this avalanche problem is unlikely to possible from light loads such as skiers. Natural avalanches are unlikely.
**Size:** If triggered expect these avalanches to be large size 2, on isolated terrain features very large, size 3
Likelihood
Expected Size
Wind Slabs
New wind slabs will begin to form during snow fall and moderate to strong south west winds. Wind slabs will be forming on old hard melt freeze crusts. Expect new wind slabs to be touchy to light triggers, propagate wide and run far and fast.
**Location:** North East thru to North West aspects and found in both the Alpine and Tree line.
**Possibility:** Triggering of this avalanche problem is likely to very likely from light loads such as skiers. Natural avalanches are possible to likely.
**Size:** If triggered expect these avalanches to be large size 2 and in isolated terrain very large size 3.
Likelihood
Expected Size
Storm Slabs
New Storm slabs are certain to form during periods of snow fall. Storm slabs will be forming on old hard surfaces that in many areas are now a melt freeze crust. Expect new storm slabs to be touchy to light triggers, propagate wide and run far and fast.
**Location:** All aspects and found in both the Alpine and Tree line.
**Possibility:** Triggering of this avalanche problem is likely to very likely from light loads such as skiers. Natural avalanches are possible to likely.
**Size:** If triggered expect these avalanches to be large size 2 and in isolated terrain very large size 3.
Likelihood
Expected Size
Valid until: Apr 10th, 2021 2:00AM
