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Avalanche Advisory
| Advisory: Ogden Area Mountains | Issued by Trent Meisenheimer for Thursday - December 29, 2016 - 4:18am |
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bottom line Today the avalanche danger is CONSIDERABLE on all upper elevation, wind loaded slopes. Wind slabs are not the only concern. In places there is a weak, faceted layer of snow near an ice crust making avalanches possible. The danger is MODERATE at mid elevations. At elevations below 7000 feet, the avalanche danger is LOW. I have a decent amount of uncertainty in the forecast today. Faceted layers are hard to predict and hard to ignore (see recent avalanche activity). For today, I would treat steep avalanche terrain as a no go, until you've gathered enough information about the slope. If this sounds complicated - then keep it simple, stick to low angle slopes under 30 degrees with nothing steep above or adjacent to you and you're good to go.
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special announcement The National Avalanche Center just released this new video on the avalanche problems and how they work. This is a key aspect to mountain travel. Understanding what type of avalanche you're dealing with. |
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current conditions Under clear skies this morning trailhead temperatures are hovering in the low teens, while the higher elevations are in the low 20's F. Winds have finally calmed down since yesterday. At upper elevations the wind is out of the west 15-20 mph gusting into the low to mid 20's. You'll find a variety of different snow textures out and about today. However, the best powder snow will be found on mid elevation slopes that have not been effected by the relentless winds over the past few days. |
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recent activity Explosives and ski cuts triggered wind slabs at ski areas on Tuesday the 27th up to 3 feet thick. Some were stubborn while some were very easy to trigger. Skiers on Ben Lomond Peak triggered many fresh wind slabs 1-2 feet deep including a few that were remotely triggered or released sympathetically when they triggered another slide (observation, avalanche1, avalanche2, avalanche3). These are major red flags. Remotely triggered avalanches are ones triggered from some distance without being on the slope that avalanches. Another slide Tuesday the 27th was intentionally triggered by a skier in the southern end of Cache Valley near Paradise at 7900 feet. It broke 1 foot deep and 300 feet wide on facets near an ice crust on a non-wind loaded slope.
Photo below of a slide that a skier triggered on Ben Lomond Peak while descending lower angle terrain adjacent to the slide path (photo D. DeBruin & B. Bauter).
See the video (D. DeBruin & B. Bauter) showing these slides and winds Tuesday the 27th on Ben Lomond Peak. |
Avalanche Problem 1
| type | aspect/elevation | characteristics |
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LIKELIHOOD
 LIKELY
UNLIKELY
SIZE
 LARGE
SMALL
TREND
 INCREASING DANGER
SAME
DECREASING DANGER
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description
Strong winds from the past few days have transported the new snow forming fresh wind slabs. Conditions will remain tricky today because some wind slabs will be stubborn while others will remain easy to trigger. We had reports from the backcountry that some of these wind slabs were breaking near an ice crust buried about a foot deep. In places this ice crust may have small, faceted snow crystals either above or below it. These faceted crystals combined with winds from the past few days will keep some wind slabs very sensitive. |
Avalanche Problem 2
| type | aspect/elevation | characteristics |
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LIKELIHOOD
 LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
 INCREASING DANGER
SAME
DECREASING DANGER
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description
There is a rain/ice crust buried about a foot deep that has faceted snow either above or below it. A skier near north Ogden Pass found this layering between 7000 and 8000 feet. Additionally, a skier intentionally triggered a slide on this layering near Paradise, UT at 7900 feet. This slide was 300 feet wide. I am unsure of how widespread this layering is, but it should be easy to find. Break out the shovel and dig down a foot or two to see if this laying exists and evaluate the bonding around this ice crust before committing to any steep terrain. Remember - when digging snow pits, we do not need to be in avalanche terrain. Pick small test slopes with little to no consequence to dig down and look at the layering before committing to larger terrain. Also, at upper elevations on NW, N, NE, and E aspects there remains a possibility of triggering a slide breaking at the ground on old snow from early November. |
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weather Today we will have clear skies and warm temperatures. Winds will remain light out of the west and southwest and should behave with speeds at upper elevations 10-15 mph with the occasional gust into the 20's. We will see high pressure and warming temperatures over the next day or two. There is another storm on tap starting late in the weekend. |
general announcements
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