Avalanche forecast

San Francisco Peaks / Kachina Peaks Wilderness

Kachina Peaks Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Expect to find new storm and wind slabs above/near treeline. Retreat from slopes where storm snow or wind-packed slabs collapse, shear and shoot long cracks over weaker, soft snow. Avoid large pockets of wind-drifted snow and pillows, especially near rollovers (convexities). Firmer wind slabs often feel hollow underfoot. There is a small chance that a human-triggered wind slab avalanche could step down, triggering a larger persistent slab avalanche. 

By midweek, warming temperatures may create wet instabilities near the snowpack surface. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Remain aware of the potential for reactive storm or wind slabs. Over the past ~36 hours, winds have been SW, W, NW,  N and NE.  New reactive slabs may be on just about any aspect. Storm slabs are usually softer, and wind slabs are usually firmer. Either way, watch for cracking, collapsing, and shearing of relatively firmer snow over softer snow. The top patrol station has reported relatively light winds with moderate gusts, but backcountry users should still continually assess for the development of new wind slabs. Winds may increase today. 

    Yesterday, near treeline on southwestern aspects, KPAC found stubborn storm slabs that were ~6" thick. Shooting cracks were all short, less than 1m long, and inconsistent.

    Below convexities, on leeward slopes, and at entrances and (cross-loaded) sides of gulleys/chutes, are key locations for wind slab development and hotspots for triggering an avalanche. Pole probe for stiffer snow over softer snow to identify areas with wind slabs. Avoid large loaded pillows of wind-deposited snow. Utilize small and inconsequential test slopes to determine how reactive new slabs are to the weight of a skier or rider. 

    There is a small chance that a human-triggered wind slab avalanche could step down,  triggering a larger avalanche on a persistent weak layer.  See persistent slab problem for more info.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–2

    Currently, easterly aspects above/near treeline are the most suspect for a persistent slab problem. Today, a person's weight will unlikely trigger any persistent slab avalanches. However, a human-triggered wind slab avalanche may step down and trigger a larger persistent slab.

    Snowpit tests and recent avalanches have focused the problem to easterly, northwest, and southwest aspects above and near treeline. The problem may exist in other isolated locations, but no recent observations have confirmed this. Some recent (but minimal) observations suggest the problem is nonexistent on northwesterly, northerly, and northeasterly slopes of Hardcore Ridge and Humphreys Cirque. Between March 19 and 22, a thick and stout melt/freeze crust developed on many sunny and southerly slopes. This m/f crust is now refrozen,  and it is unlikely that a person's weight will penetrate this layer, collapsing any weak layers below. 

    The primary layers of concern are facets above and below the late February melt/freeze crust, topped by a hard slab from the St. Patrick's Day Storm Cycle (3/14-18). The February melt/freeze crust will be approximately 60-80cm below the surface. It will be difficult to distinguish the late February crust on shady/northerly slopes. Use delicate probe work. 

    Last Wednesday (3/20),  a D2 persistent slab avalanche (easterly aspect) was triggered on the skin track out of Humphrey's Cirque (HS-ASr-R1D2-I).  This avalanche was remotely triggered by a collapse that ran towards a rock outcrop and could have gone larger.  Fortunately, no one was caught in this event.  It failed in facets just above the late February melt/freeze crust. See the avalanche details and debrief here. 

    (3/20/2024)

    Last Wednesday's (3/20) D2 persistent slab avalanche was remotely and unintentionally triggered on the east-facing skin track exiting Humphrey's Cirque. The connected slab of this avalanche PROPAGATED and cracked ~100 feet beyond the crown (and above the skin track) but did not slide. Fortunately, no one was caught in this event. 

Avalanche Discussion

Yesterday, near treeline on southwestern aspects, KPAC found stubborn storm slabs that were ~6" thick. Shooting cracks were all short, less than 1m long, and inconsistent. Your number one problem today will be recent storm/wind slabs. Travelers are urged to check the bonding of new snow to the March 19-22 melt/freeze crust below. So far, the new/old snow bonding has been good on the southerly and southwesterly slopes. 

Crampons and ice axe will be helpful above treeline where new snow has been scoured to the hard and stout melt/freeze crust of approximately South, West, and East slopes. 

On Saturday (March 23), instability tests (near the easterly 3/20 crown line of the Humphreys Cirque/Rustler Peak avalanche) indicated that the problem has become more stubborn to propagate, but it is still there. On other NW, NE, and N slopes in the Inner Basin, instability tests indicated that propagation was unlikely on layers of concern near the late February m/f crust. 

By midweek and through the weekend, warming temperatures may create wet instabilities near the snowpack surface. 

Recent snowpits can be found at https://snowpilot.org/snowpits/query?field_loaction_tid=4. 

Come join Kachina Peaks Avalanche Center on Saturday, April 6th, at the Agassiz Lodge deck for the Mikee Linville Fundraiser!  All proceeds from this event go to our scholarship fund, which, to date, has resulted in over 29K of scholarship benefits!  For more information on how to get involved, visit kachinapeaks.org.  Many thanks to everyone who made our avalanche courses a success this season, and a big thank you to all our participants! KPAC is especially grateful to our generous community. Your support makes avalanche forecasting and education possible in Northern Arizona. 100% of KPAC's funding comes from fundraisers, donations, and grants - your contribution matters!

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