Idaho City Mountains Avalanche Forecast

The avalanche forecast for the Idaho City Mountains will be discontinued until the next 2026-2027 winter.

This forecast is essentially the same as the avalanche forecast released a few days ago. With the caveat that the storm expected to start precipitating in our area by Thursday did not materialize. The snow total for this storm has declined.

A warm winter storm with snow levels near 6000 feet is forecast to precipitate as much as 20 cm of new snow in the Idaho City Mountains over a period of 48 hours ending Sunday morning. The precipitation event commences on Friday night.

The new snow is expected to bond well with the variable snow surfaces in the current snowpack.

Wind slabs are expected at elevations above 7000 feet due to strong (>12 m/s) westerly winds with gusts in the extreme range as the cold front transits the area.

A warm winter storm with snow levels above 6000 feet is forecast to precipitate as much as 25 cm of new snow in the Idaho City Mountains over a period of 72 hours ending Saturday morning.

The new snow is expected to bond well with the variable snow surfaces in the current snowpack.

Wind slabs are expected at elevations above 7000 feet, as winds increase on Thursday to moderate (> 7-8 m/s) with strong gusts (> 11-12 m/s).

From Monday to Thursday, snowfall in the Idaho City Mountains could total 20 to 25 cm. The first storm is on Monday, with light and wet precipitation.

A second more productive precipitation event will reach the Idaho City Mountains by Wednesday. The second storm will be accompanied by stronger SW winds and shifting to the NW post-storm. Temperatures will be on the milder side, with heavier and wetter snow at elevations below 7500 feet.

Wind slab and storm slab avalanches are expected in steep terrain. Deep slab instability cannot be ruled out in steep, northern-aspect terrain.

During the last 7 days, nature blessed the Mores Creek Summit area with an excess of 80 mm of SWE, almost 80 cm of snow at 10% density.

The first two storm periods ended on February 19th, with AWSOME POWDER snowfall totals exceeding 50 mm of SWE.  The significant precipitation total and rapid precipitation rate triggered a widespread avalanche cycle. The buried surface hoar weak layer released at many northerly and easterly slopes and propagated to low 30-degree slope angles.

The latest two storm forecasts predict snow totals of 30-40 cm over 48 hours. The new snow over an uncertain distribution of buried reactive, propagating weak layers requires conservative terrain selection. Complex terrain is to be avoided.

We are in a transition phase, during which Propagating (and persistent) weak-layer avalanche releases in the Idaho City Mountains are becoming unlikely. The current meteorological conditions favor the rounding and sintering of recent snow with various old-snow surfaces.

Winter has returned! And there is new snow on top of old snow surfaces.

Propagating (and persistent) weak-layer avalanche releases in the Idaho City Mountains are likely.

Three weeks of extended snow drought dominate the development of the snowpack. The melt-freeze and rounded facets layers continue to sinter. This is reflected in snowpack densities exceeding 20%.

The extensive surface hoar observed in recent weeks has been buried by Wednesday, January 28th, 10 cm of NEW snow. An additional 4-6 cm of snow may fall on January 29th.

The likelihood of avalanche releases is UNLIKELY. Pockets of poor snopack structure can be found, but they lack reactivity. 

The likelihood of slab or loose avalanches is UNLIKELY. Identifying pockets of instability in the Idaho City Mountains is challenging at this time.