Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 7 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Continued wind transport has left slabs of wind-drifted snow susceptible to triggering. If more sunshine than forecast arrives, expect a wet avalanche problem to develop in the abundant, cold, dry surface snow. Triggering a dangerous avalanche on a buried weak layer remains a concern.

Choose low-angle slopes sheltered from the sun and wind for a safer experience.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Cold, dry snow is widespread in the mountains, and any slope that sees direct sun today may produce loose avalanches as surface snow warms (dry or wet). Cloud cover is the wild card and will determine where this problem occurs. Meanwhile, southwest- and west-facing slopes may have already seen some melting from Saturday afternoon’s sunshine, while east-facing slopes could be seeing their first exposure to sunlight this morning. 

    Managing this problem is fairly straightforward. If the sun is shining on the slope you are on—or on slopes above you—expect the potential for snow tostart shedding and move to lower-angle terrain or switch aspects and step into the shade. Snow falling from trees, rollerballs, pinwheels, or soggy surface snow are good signs that loose avalanche problems may be developing. Keep in mind that snow on rock bands, cliffy features, and high above you can warm and release before the snow at your feet does. Even small wet loose avalanches can entrain significant snow and have serious consequences if they knock you off balance or push you into terrain traps.

    (2/5/2025)

    Wet loose activity on a steep and rocky southerly slope. 

    Photo: Flathead Avalanche Center

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Recent light, dry snowfall continues to be transported by south-southwest winds, forming fresh slabs. These features may disguise several generations of slabs built over the past week. You will find these near and below ridgelines, in mid-slope gullies, and behind terrain features such as rock outcroppings and ribs.

    Recent cornice growth has been impressive, increasing the chance of a triggered slide on the slope below, as noted by observers in the Swan yesterday.

    Signs that wind has affected an area include textured snow surfaces (attached image), dune-shaped drifts, and cornices. The surface will feel noticeably firmer than in more protected areas. 

    Cracking underfoot or a sled indicates you have found a slab. Collapsing and cracks that shoot away from you confirm the slab is sensitive. If you encounter a dense surface over softer snow, choose a lower-angle slope to increase your safety margin.

    (1/10/2026) This scalloped or textured surface indicates that the wind has affected this slope. Wind moves from left to right in this image. This snow will feel noticeably denser than that found in more protected areas. Photo: Etienne Surrette

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Triggering a 1-3 foot thick slab avalanche on a buried weak layer remains possible. Three rider-triggered slides occurred on this layer in the Whitefish Range over the past few days. 

    The conditions for a Persistent Slab avalanche are not present on all slopes, and it's challenging to determine where they are or aren't. The safest bet is to assume that the troublesome slab/weak-layer/crust combination exists on all slopes. You may or may not experience obvious signs of instability—snowpack collapsing or cracks shooting out from your skis or sled—before triggering an avalanche. The resulting slides may propagate farther than expected, resulting in a large avalanche.

    Friday's hard slab avalanche was triggered remotely from the side of a steep slope. This could also occur from lower-angle terrain above or below a steep slope.

    Reduce your chances of triggering one of these beasts by selecting low-angle slopes not connected to steeper terrain. 

    (1/10/2026)

    This crown of this large skier-triggered avalanche was at least 250' wide and 2' deep. These side by side images show the crown from the same point looking in opposite directions. The crown continued out of view in both images, wrapping multiple terrain features and aspects.

    Photo: Mark Dundas

Avalanche Discussion

Saturday's sunny skies and deep, cold, unconsolidated snow drew many people out to enjoy the backcountry. Riders experienced superb snow conditions in sheltered terrain, with wind-affected snow on wind-exposed slopes. We received a whopping dozen public observations from all zones! Thank you so much for helping us out.

Josh and I visited the southern Whitefish Range on Friday to take a closer look at a large avalanche remotely triggered by a rider. This slide failed on a buried weak layer 2 feet below the surface. We also noted a fresh but smaller slide on this same layer, triggered by a snowbiker. You can read the observation here. 

Wet Loose: Today's wild card is the amount of sun we will receive. There is a lot of dry, cold snow available to become wet and develop wet loose problems. If today's forecast of partly to mostly cloudy conditions becomes mostly sunny, wet loose activity will become the primary problem across all three zones. 

Wind Slab: Wind continues to blow and transport snow in all zones. However, we believe this problem is isolated in the Whitefish Range and Swan Range, where less snow has fallen, and we have removed this from today's problem list.  We have removed the wind slab problem from these zones, but you should continue to evaluate leeward slopes that show fresh evidence of wind-affected snow. 

Unfortunately, a large avalanche resulted in the deaths of two riders in the Washington Cascades. You can read more about that here. 

Regioni coperte