Park staff use a howitzer to reduce avalanche danger.

Sylvan Pass Winter Travel

The park’s East Entrance road crosses 20 avalanche paths through Sylvan Pass.

Yellowstone has been conducting avalanche hazard mitigation operations at Sylvan Pass since 1973. The final rule implementing the long-term plan to guide management of winter use in Yellowstone calls for Sylvan Pass to remain open to motorized oversnow travel.

The park is using a combined helicopter and howitzer program to conduct avalanche hazard mitigation operations this winter on Sylvan Pass. Rangers monitor weather and snow conditions and review a wide range of data to aid them in forecasting the avalanche danger for Sylvan Pass.

Some sources of the data include the following web sites:

• Current National Weather Service Forecast for Yellowstone National Park
  
  
• Lake Ranger Station weather data from the National Weather Service weather station
  
  
• Sylvan Road weather data from the NRCS SNOwpack TELemetry site
  
  
• Area Forecast Discussion from the National Weather Service in Riverton, WY
  
  
• Regional Satellite Images from the National Weather Service
  
  
• U.S. Current Surface and Forecast Weather Maps from the National Weather Service

Sylvan Pass may be temporarily closed to all travel when avalanche forecasting shows travel is unsafe. It will remain closed until forecast conditions permit Yellowstone National Park employees to conduct avalanche hazard mitigation operations and groom the route for motorized oversnow travel.

Methods used to reduce the risk of avalanche hazard mitigation this winter may result in longer temporary closures between the detection of avalanche risk and the reopening of Sylvan Pass to motorized oversnow travel compared to historic avalanche hazard mitigation operations.

You can find the current status of Sylvan Pass and other interior park roads groomed for motorized oversnow travel by going to the Winter Daily Reports at http://www.nps.gov/yell/planyourvisit/winterreports.htm.

See Current Conditions and Updates for other related seasonal information.