Issued: 06/06/2011 8:11 AM by Ethan Greene |
Expires: 10/31/2011 12:00 PM 2 2 |
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The Colorado Avalanche Information Center is a program within the Department of Natural Resources. | |
Highlights | |
The staff at the CAIC are starting to follow weather patterns and it looks like winter is on its way. The National Weather Service issued a winter storm watch for the central mountain zones and a winter storm warning for the San Juan Mountains on October 6th so winter is about to arrive. More winter like weather looks to linger into the weekend. We will resume our weather products on November 1, 2011 and our regular avalanche and snowpack forecasts around mid-November..
Even though we are not issuing advisories, we are still collecting information. Please send us your observations and we'll keep the list of Field Reports and Avalanches current. | |
Weather Discussion | |
A couple of smaller storms moved through the state in September which left some snow down to treeline. Most of this snow melted off, but some did linger on north aspects and on old summer snow fileds. A vigourous low pressure trough and a strong jet stream were forecast to move into Colorado the first week in October. Winter is knocking on our door and it won't be long until fresh slabs begin to develop across the high country. Strong winds and significant snowfall are in the forecast so start thinking avalanche if you have plans to travel into the high country.
If you're headed into the high country this fall use our Weather Stations by Zone page to check wind, temperature and precipitation numbers. You can use our Weather Stations by Zone page to monitor past and present weather conditions too. | |
Snowpack & Avalanche Discussion | |
Fall and Early Winter Avalanche Safety
Although no avalanche incidents have been reported so far, one natural avalanche was reported from Bear Creek near Telluride during the last week in September. There have been avalanche fatalities and accidents in Colorado every month of the year. With snow already settling into the high country it is time for us to start thinking about mountain weather and snowpack. It is not unusual for avalanche incidents and fatalities to make headlines in our state long before most of us are thinking about the consequences of an early season encounter.
The CAIC has already begun to monitor the 2011-2012 snowpack. No avalanche incidents have been reported yet. However, it should come as no surprise that once snow begins to accumulate, avalanches, both natural and triggered, can be expected. It is common for us to see reports of people caught in avalanches every year in October. An early season encounter with an avalanche will often come with a ride through rocks, downed timber, stumps and other obstacles which can quickly bring an end to your riding season. Always think of what consequences are possible if you were to get caught and take a ride in an avalanche.
Across many areas of the state over a foot of new snow is expected for the first week in October. Strong winds associated with the jet stream will move this new snow into sheltered lee pockets and onto old summer snow fields. Temperatures have shown a steady decrease over the last couple weeks meaning a shallow snow cover will begin its annual faceting process and begin to form future weak layers. Until daily public forecasts begin, here are a few things to think about as the winter snowpack develops.
° Fall and a taste of winter have returned to Colorado’s high country. Snow began to stick on the higher terrain by mid-September. Every season people have encounters with wintertime slab avalanches as early as August or September. Anyone traveling in the mountains, including hikers, hunters, sledders, skiers, riders and ice climbers, needs to be aware of the avalanche threat as soon as snow starts to accumulate on steep slopes.
° People are often misled when they see grass and brush sticking out of the snow surface. You should start thinking about avalanches any time you have snow resting on a steep slope. Remember, all you need is a slab resting on a weak layer of snow. The ground can easily act as a bed surface, even if it’s only a few inches below the snow surface.
° Old summer snow fields can act as the perfect bed surface too. Hard frozen old snow with new snow on top are common culprits in early season avalanche incidents.
° Early in the snow season there is not much snow on the ground. This means that rocks and stumps are near the snow surface. If you get caught in an avalanche you might get tumbled through rocks, stumps, and downed timber. These obstacles can do great bodily harm to backcountry users traveling through them at high speeds. Knee pads, helmets and full body armor may not be a solution to this problem. Even a very small slide can cause great harm if the terrain is unfriendly.Don't let an early-season injury ruin your winter!
° Wind drifts will create thicker slabs. Strong winds can take a three inch snowstorm and quickly build an 18” wind slab. Areas with shallow snow may be very close to deep drifted areas. It may be quite easy to move from a very safe area to a very dangerous area without traveling very far. Wind drifts will be denser than the new snow and thick hard snow on light fluffy snow is a great setup for avalanching.
° Once the sun returns after a storm cycle and warm temperatures cause the new snow to melt, look to see where the pockets of snow remain. The snow that lingers in sheltered areas and shady slopes could be the weak layer after the next snowfall. These areas could also become recurring problem areas throughout the winter depending on how the winter snowpack develops.
° Pockets of instability can develop quickly above early season ice climbs. Climbers should know the terrain above their route as rapid warming or heavy wind loading can quickly work to build slab or loose snow avalanches which can nudge a precariously perched climber into a bad fall.
° Hunters traveling across the high country need to exercise greater caution on steep terrain (steeper than 30 degrees with accumulated snow) when crossing ridges from one valley to another.
You can use our Weather Stations by Zone page to monitor past and present weather conditions.
Have a safe fall and even before we start issuing regular products, travel with all the right gear, and think avalanche. | |
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