Avalanche Advisory
Advisory: Provo Area Mountains Issued by Drew Hardesty for Sunday - January 21, 2018 - 7:31am
bottom line

A MODERATE danger exists for new wind drifts and dry snow sluffs in the steepest terrain of the mid and upper elevations. Pockets of "scary" MODERATE danger still exist for triggering a 1-2' deep persistent slab avalanche into old snow. These are more pronounced on steep northwesterly to northeasterly slopes above about 8500'. As always, good habits save lives: make a plan, one at a time on the slope, get out of the way at the bottom.

Hot Tip! Again, terrain is your friend. The safest and arguably best riding conditions can be found on the low angle southerly slopes with no overhead hazard.
special announcement

Episode 3 of the UAC podcast went live last night. We talk with UDOT Avalanche Program Supervisor Bill Nalli on how he and his teams keep the Greatest Snow on Earth from avalanching over the open roads and highways of the state. Find it on our blog site (linked above), iTunes, Stitcher, or wherever you get your podcasts.

Do you know the parable of the Scorpion and the Frog? A short piece of fiction from Mineral Fork here.
current conditions

It's the stuff that dreams are made of. 6-10" of right-side-up powder with some of the best conditions of the year. Currently skies are mostly cloudy. Northwest winds are light and less than 15mph. Mountain temperatures have plummeted to the 10°F.

recent activity

We didn't hear of any activity in the Provo mountains but would expect some longer running loose snow avalanches in the steepest most confined terrain. Three larger persistent slab avalaches were triggered in the Central Wasatch 2-3' deep in northerly terrain at 9600'.

Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

Watch for the cold smoke to move with human provocation on the steepest slopes of all aspects at the mid and upper elevations. I expect the sluffs to move fast and far on the slick underlying sun and wind crusts, entraining all the storm snow in the path below. The good news is that these types of avalanches readily show their cards and hold little mystery: they respond to ski cuts and cornice drops and break at your feet or machine rather than above you. These avalanches, however, can move at light-speed, easily trip up a slow or unsuspecting skier or rider and pile up deeply in a terrain trap. The key is to move diagonally across the slope or from area of safety to area of safety to avoid being engulfed in your own sluff. Google "sluff-management".
Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

The new storm snow is only window dressing for the continued persistent slab problems in our conditionally unstable snowpack. We've slowly transitioned to a "low-probability - high consequence" regime where likelihood and sensitivity have greatly diminished but the consequences remain severe. Note that the additional stress of a more superficial storm snow avalanche may subsequently trigger one of these persistent slab avalanches. In sharp contrast to loose snow avalanches, this avalanche problem often holds its cards close where tests and observations may be inconsistent and misleading and avalanches may break well above the committed skier or rider. Again, use the infographics below to contrast with loose snow avalanches above. Note three of these were triggered in northerly terrain at 9600' in the central Wasatch yesterday.
Avalanche Problem 3
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

It only takes just a bit of wind to move and slab the very low density snow. Super soft wind drifts may be found in a variety of lee encatchment zones and may be triggered at a distance. The north winds should erode many upper north facing starting zones and drift onto the steep west to south to east facing paths. Terrain channelling at the mid-elevations may allow soft wind drifts to develop on many aspects.
weather

We'll see the last few snowflakes winding down and skies should start to break through the afternoon. 20-25mph northwesterly winds are expected to lose steam over the course of the day. Temps will be in the single digits and low teens. We'll see a few weak disturbances over the next several days with a more potent storm for Thursday/Friday.
general announcements

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This information does not apply to developed ski areas or highways where avalanche control is normally done. This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.