Hatcher Pass
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The Bottom Line
A significant storm with heavy precipitation will overload our weak snowpack and result in large natural avalanches today. Avalanches will be very likely on all aspects at the mid to upper elevations by the afternoon.
Overnight we received 11″ of new snow with another 10-14″ forecasted for today, and another 8″ forecasted for this evening into the early hours tomorrow morning. Storm totals could push 30 inches.
The hazard is CONSIDERABLE at mid and upper elevations this morning rising to HIGH by the afternoon. As this storm continues to produce additional precipitation today, the avalanche hazard will increase.
With increasing avalanche hazard, natural avalanches very likely, poor road conditions, and poor visibility, we do not recommend travel in the backcountry today. This is the time to wait out the storm.
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| Travel Advice | Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. | Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. | Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. | Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. | Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain. |
| Likelihood of Avalanches | Natural and human-triggered avalanches unlikely. | Natural avalanches unlikely; human-triggered avalanches possible. | Natural avalanches possible; human-triggered avalanches likely. | Natural avalanches likely; human-triggered avalanches very likely. | Natural and human-triggered avalanches certain. |
| Avalanche Size and Distribution | Small avalanches in isolated areas or extreme terrain. | Small avalanches in specific areas; or large avalanches in isolated areas. | Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. | Large avalanches in many areas; or very large avalanches in specific areas. | Very large avalanches in many areas. |
The 2023/24 season has started with a bang! There are simply too many avalanches to count. The take home: Each time our basal weak snowpack is loaded it is re-activated resulting in avalanches. This problem will persist and is not going away anytime soon. Below are a few pictures from both the 11/8 storm and the 11/9 wind event, plus the 11/11-12 storm cycle.
11/11-12 Tea Cup, Natural avalanche. Of note: significant wide propagation indication high continuity in the weak layer = Red Flag
11/11-12 Marmot SW Face, Natural avalanches, small to large in size
11/11-12 Marmot SW Face, sidewall above the Death Gulley, Large natural avalanches
Punk Spines. We think these large natural avalanches which have been covered with newer occurred in the 11/8 storm and 11/9 wind event.
NWS AVG Forecast for Hatcher Pass
NWS AVG Forecast for Hatcher Pass
Marmot web cam at 3500′
| Signal Word | Size (D scale) | Simple Descriptor |
| Small | 1 | Unlikely to bury a person |
| Large | 2 | Can bury a person |
| Very Large | 3 | Can destroy a house |
| Historic | 4 & 5 | Can destroy part or all of a village |
A widespread poor snowpack structure with weak basal October facets (sugar snow) are the concern. This layer has already failed in previous storm cycles, and will again in the current storm cycle. Avalanches on this layer may take out the whole snowpack, sliding at or near the ground level. Average depths of the snowpack at mid to upper elevations appear to be 12″ to 27″.
Remotely triggered avalanches will be possible. As a reminder, this means it will be possible to trigger an avalanche above you or adjacent to you from the flats below.
Today appears to be the peak of the storm, tapering off tomorrow.
Overnight we picked up 11′ of new snow in 1.5″ of SWE. Additionally, we saw strong winds from the SE capable of transporting available low density snow and loading Northwest to North aspects at upper elevations. That’s a big load for this weak snowpack. But it hasn’t quit yet, and continues to snow, adding even more load onto our weak snowpack. Today NWS is calling for an additional 10-14″ of snow.
This morning we are rating the mid and upper elevations at CONSIDERABLE, which means that natural avalanches are possible and human triggered are likely. However, as this storm continues throughout the day and we see the 10-14″ of snow verify, the avalanche hazard will rise to HIGH this afternoon with natural avalanches likely and human triggered very likely.
At the lower elevations, we are issuing a moderate avalanche hazard. A unique set up with early-season storm patterns favored the mid and upper elevations with snow while leaving the lower elevation snowless. This is why there is a stark difference in the hazard rating. If you get out into the lower elevation you must pay close attention to the runout of slopes from above in the mid and upper elevations which could run into the lower elevations.
| Signal Word | Size (D scale) | Simple Descriptor |
| Small | 1 | Unlikely to bury a person |
| Large | 2 | Can bury a person |
| Very Large | 3 | Can destroy a house |
| Historic | 4 & 5 | Can destroy part or all of a village |
Our primary concern with this storm cycle is the deeper persistent weak layer near the base of the snowpack. However, storm snow avalanches will be just as much of a problem, failing at the new snow / old snow interface. These will be shallower and smaller in size, but still capable of burying, injuring, or killing a person. They will also have the potential to step down to the persistent weak layer, producing larger more dangerous avalanches.
