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Western Wyoming Avalanche Advisory
Jackson Ranger District, POB 1689, Jackson WY 83001
Issued: Mon December 29, 2008 7:00 PM
SITUATION:
Special Information: The Wyoming Department of Transportation will close Teton Pass at 8 A.M. Tuesday for avalanche reduction work. Re-opening time will be dependant on the amount of snow impacting the highway.
An upper level low pressure system brought dense snow, strong winds and very warm temperatures to Western Wyoming Monday. Winds at 10,4000 feet were west-southwesterly at 30 to 40 mile per hour averages with gusts into the 70s. Four to six inches of new snow fell during the day in the Tetons with as much as a half inch of moisture. In the past thirty six hours 6 to 8 inches of new snow have contained one and three quarters inches of water. The Continental Divide/Togwotee Pass area received 1 - 4 inches of snow and the Southwest Trails/Greys River area accumulated 2 – 4 inches. Valley floor temperatures reached into the forties and numerous roof and road cut slides occurred.
Avalanche control work at the Jackson Hole Mountain Resort produced numerous hard slab avalanches to five feet in depth and running full track. The Headwall area released a moderate slide then a team used an explosive charge to control a remaining pocket. The charge pulled out most of the remaining headwall and ran to below the restaurant burying three patrolmen briefly after the debris flowed around a ninety degree corner of the building and continuing several yards. During a brief clearing in the weather several large, long crowns from naturally occurring avalanches were reported on northeasterly aspects from 8,500 to 10,000 feet. Most of these slides continue to run on the persistent mid-November crust.
FORECAST FOR Tuesday December 30, 2008 :
Another burst of snow is forecasted for Monday evening with up to four inches of snow in the mountains. Tuesday will be drier and cooler with a chance of light snow and morning lows in the single digits and daytime highs in the teens. Winds will taper Monday evening from southwesterly at 20 m.p.h. to westerly at 15 to 20 Tuesday.
Continued new snow and strong winds will maintain the general avalanche hazard at HIGH in the Tetons and Greys River/Southwest Trails areas. Large dangerous natural and human triggered avalanches are likely. It may be more difficult to trigger slides with colder air temperatures but we have not seen significant stabilization over time with this snowpack. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED.
The general avalanche hazard in the Togwotee Pass/Continental Divide areas will be CONSIDERABLE. Dangerous human triggered slab avalanches and natural avalanche activity are possible. Conservative decisions regarding route selection are essential for safe travel in avalanche terrain.
TREND FOR WEDNESDAY AND THURSDAY :
Another storm system is forecast to bring several inches to the region Wednesday then colder drier conditions are expected Thursday
Avalanche conditions will continue dangerous.
EXTREME: Wide spread areas of unstable snow exist and avalanches are certain on some slopes. Backcountry travel should be avoided.
HIGH: Mostly unstable snow exists on a variety of aspects and slope angles. Natural avalanches are likely. Travel in avalanche terrain is not recommended.
CONSIDERABLE: Dangerous unstable slabs exist on steep terrain on certain aspects. Human triggered avalanches probable. Natural avalanches possible.
MODERATE: Areas of unstable snow exist. Human triggered avalanches are possible. Larger triggers may be necessary as the snowpack becomes more stable. Use caution.
LOW: Mostly stable snow exists. Avalanches are unlikely except in isolated pockets.
Please be careful out there guys! It couldn't be much worse right now.
Jackson Ranger District, POB 1689, Jackson WY 83001
Issued: Mon December 29, 2008 7:00 PM
SITUATION:
Special Information: The Wyoming Department of Transportation will close Teton Pass at 8 A.M. Tuesday for avalanche reduction work. Re-opening time will be dependant on the amount of snow impacting the highway.
An upper level low pressure system brought dense snow, strong winds and very warm temperatures to Western Wyoming Monday. Winds at 10,4000 feet were west-southwesterly at 30 to 40 mile per hour averages with gusts into the 70s. Four to six inches of new snow fell during the day in the Tetons with as much as a half inch of moisture. In the past thirty six hours 6 to 8 inches of new snow have contained one and three quarters inches of water. The Continental Divide/Togwotee Pass area received 1 - 4 inches of snow and the Southwest Trails/Greys River area accumulated 2 – 4 inches. Valley floor temperatures reached into the forties and numerous roof and road cut slides occurred.
Avalanche control work at the Jackson Hole Mountain Resort produced numerous hard slab avalanches to five feet in depth and running full track. The Headwall area released a moderate slide then a team used an explosive charge to control a remaining pocket. The charge pulled out most of the remaining headwall and ran to below the restaurant burying three patrolmen briefly after the debris flowed around a ninety degree corner of the building and continuing several yards. During a brief clearing in the weather several large, long crowns from naturally occurring avalanches were reported on northeasterly aspects from 8,500 to 10,000 feet. Most of these slides continue to run on the persistent mid-November crust.
FORECAST FOR Tuesday December 30, 2008 :
Another burst of snow is forecasted for Monday evening with up to four inches of snow in the mountains. Tuesday will be drier and cooler with a chance of light snow and morning lows in the single digits and daytime highs in the teens. Winds will taper Monday evening from southwesterly at 20 m.p.h. to westerly at 15 to 20 Tuesday.
Continued new snow and strong winds will maintain the general avalanche hazard at HIGH in the Tetons and Greys River/Southwest Trails areas. Large dangerous natural and human triggered avalanches are likely. It may be more difficult to trigger slides with colder air temperatures but we have not seen significant stabilization over time with this snowpack. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED.
The general avalanche hazard in the Togwotee Pass/Continental Divide areas will be CONSIDERABLE. Dangerous human triggered slab avalanches and natural avalanche activity are possible. Conservative decisions regarding route selection are essential for safe travel in avalanche terrain.
TREND FOR WEDNESDAY AND THURSDAY :
Another storm system is forecast to bring several inches to the region Wednesday then colder drier conditions are expected Thursday
Avalanche conditions will continue dangerous.
EXTREME: Wide spread areas of unstable snow exist and avalanches are certain on some slopes. Backcountry travel should be avoided.
HIGH: Mostly unstable snow exists on a variety of aspects and slope angles. Natural avalanches are likely. Travel in avalanche terrain is not recommended.
CONSIDERABLE: Dangerous unstable slabs exist on steep terrain on certain aspects. Human triggered avalanches probable. Natural avalanches possible.
MODERATE: Areas of unstable snow exist. Human triggered avalanches are possible. Larger triggers may be necessary as the snowpack becomes more stable. Use caution.
LOW: Mostly stable snow exists. Avalanches are unlikely except in isolated pockets.
Please be careful out there guys! It couldn't be much worse right now.
