UDOT PLANNED AVALANCHE CLOSURES!!

Forecast for the Ogden Area Mountains

Drew Hardesty
Issued by Drew Hardesty for
Monday, April 1, 2019
This morning the avalanche danger is LOW on all east through south through west aspects. By mid morning and early afternoon the avalanche danger will quickly rise to MODERATE or higher in the steep sunlit terrain and low northerly terrain due to strong sun, warming temperatures, and possible greenhousing. Human and natural wet loose avalanches will be possible.

The mid and upper elevation steep northwest through easterly facing terrain has a MODERATE danger for triggering an avalanche 1-3' deep on one, perhaps two buried persistent weak layers.
Low
Moderate
Considerable
High
Extreme
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Special Announcements
Forecast by Zinnia Wilson and approved by Drew Hardesty
Utah has a rich history of avalanches. From the earlier mining days of Alta to the start of avalanche research and snow science in the US in Little Cottonwood Canyon in 1939. Snowpack and weather data has been collected from the Alta Guard Station every year since making it the longest snow plot history in the US. These roots made the UAC an early leader in avalanche education and forecasting.
Weather and Snow
Last night temperatures dropped into the low 20's °F above 9,000', while barely dipping below freezing at lower and mid-elevations. Another night of clear skies allowed for a solid refreeze of the snow surface at all elevations, but likely less deep than we saw yesterday. Winds were generally light and variable at the lower elevations, with moderate speeds from the southwest through northwest at exposed upper elevations.
The overall warming trend continues today, with temperatures several degrees warmer than yesterday: We'll reach mid 30's °F in the upper elevations, and high 40's °F (even into the 50's°F) at 7,000 feet. Winds will remain light to moderate, shifting more to the south around noon. At the same time, cloud cover should begin to develop.
Recent Avalanches
Ski areas reported a shorter window of wet loose avalanching yesterday than the day prior, with the previous night's refreeze keeping activity at bay until late morning. Push-a-lanches and small wet slides were common.
A skier in the Snowbasin backcountry triggered a wind slab in east-facing Mt. Ogden Chute at 9,400', breaking 14" deep and 30' wide (pic below). Two sets of ski tracks were taken out in the slide. On Thunderdome, near Powder Mountain, an intentional ski cut on a north-northeast aspect at 8,200' released a 10" by 100' avalanche that traveled 500' on a knife hard melt freeze crust. Finally, on Francis Peak a soft windslab natural avalanche was reported, deep enough to bury or injure a person.
On Friday an avalanche was triggered on "Scrapies", a steep east-facing slope at 9,100'. Powder Mountain conducted an investigation of the avalanche involvement in their out of bounds terrain here. This is private property; see video below.
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Avalanche Problem #1
Wet Snow
Type
Location
Likelihood
Size
Description
Strong sun and warming temperatures will again be the main issue today; today's temperatures will be warmer than yesterday's, and the refreeze last night was less deep. There's some uncertainty around the cloud cover expected to develop around noon. Sky cover may keep snow surfaces on the southwest and west cooler, lowering the afternoon hazard. At the same time, thin cloud cover could cause greenhousing and increased wet snow activity on the mid elevation northerlies that have remained relatively dry since the Thursday/Friday storm.
The effects of cloud cover may be difficult to forecast, but they're easy to now-cast. You'll know you've overstayed your welcome if your skis are digging trenches, you step out of your binding and sink to your knee, or you're watching roller-balls zip past. Best to avoid exits with mandatory exposure to warming slopes.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
A buried weak layer still exists on protected mid and upper elevation northerly facing slopes. This is buried 2-3' deep and may be triggered at a distance. The last reported collapses was on Friday. Surface hoar heals notoriously slowly, and its easy to forget the problem when the obvious clues become less frequent. Its tempting to ignore the problem when its habitat is exactly where the skiing/riding is best. In suspect terrain, a quick 2-3 foot pit could reveal the thin grey line or the alarming test result that keeps you out of harms way. Weak interfaces may also be found before this last storm at the mid and upper elevations (see Scrapey's avalanche).
Photo: Buried weak layer in the Ogden mountains.
General Announcements
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.