Trip Planning for Island Park

as of 5:00 am
Today0″ | NA
Apr 27 0″ | NA
Apr 26 0″ | NA
9885′     04/24 at 11:00
24.0℉
NE - 11mph
Gusts 20 mph
8750′     02/05 at 19:07
61.5″ Depth
1.1″New
7710′     04/28 at 07:00
33℉
42″ Depth
Primary Problem: Wind Slab
Bottom Line: Avalanche conditions are complicated by a mix of winter and spring weather this week. Rain and snow fell on mountain snowpacks, with the most significant precipitation in the Bridger Range for the start of the week. The more new snow there is, the more likely you are to encounter avalanches and the larger their potential size. If your travel plans take you to slopes steeper than 30 degrees, assess how the new and wind-drifted snow is bonding to the old snow surface by watching for clear signs of instability, such as avalanches and shooting cracks. If rain fell on the snowpack and as temperatures warm, breaking through an unsupportable and slushy snowpack, seeing pinwheels of wet snow and small wet slides are indicators of wet snow instability.

Past 5 Days

Sat Apr 19

Low
Sun Apr 20

Low
Mon Apr 21

None
Fri Apr 25

None
Today

None

Relevant Photos

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Videos- Island Park

Snowpit Profiles- Island Park

 

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Weather Forecast Island Park

Extended Forecast for

10 Miles ESE Lakeview MT

  • Today

    Today: Snow showers likely, possibly mixing with rain after 2pm, then gradually ending. The snow could be heavy at times.  Cloudy, then gradually becoming mostly sunny, with a high near 40. North wind 11 to 14 mph, with gusts as high as 22 mph.  Chance of precipitation is 70%. Total daytime snow accumulation of 1 to 3 inches possible.

    High: 40 °F

    Heavy Snow
    then Chance
    Rain/Snow

  • Tonight

    Tonight: A slight chance of rain and snow showers, mainly between 2am and 4am.  Partly cloudy, with a low around 29. North northwest wind 6 to 10 mph becoming south southwest after midnight. Winds could gust as high as 18 mph.  Chance of precipitation is 20%.

    Low: 29 °F

    Slight Chance
    Rain/Snow

  • Tuesday

    Tuesday: A 50 percent chance of showers, mainly after 1pm.  Increasing clouds, with a high near 45. South southwest wind 6 to 16 mph, with gusts as high as 26 mph.

    High: 45 °F

    Partly Sunny
    then Chance
    Showers

  • Tuesday Night

    Tuesday Night: Rain showers before midnight, then a chance of rain and snow showers between midnight and 3am, then a chance of snow showers after 3am.  Low around 29. Southwest wind 10 to 14 mph becoming north northwest after midnight. Winds could gust as high as 22 mph.  Chance of precipitation is 90%. New snow accumulation of less than a half inch possible.

    Low: 29 °F

    Showers then
    Chance
    Rain/Snow

  • Wednesday

    Wednesday: A 30 percent chance of snow showers, mainly after noon.  Mostly sunny, with a high near 44. North northwest wind 11 to 13 mph, with gusts as high as 21 mph.  Little or no snow accumulation expected.

    High: 44 °F

    Chance Snow
    Showers

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 28. North wind 9 to 13 mph, with gusts as high as 23 mph.

    Low: 28 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 52. North wind 6 to 10 mph becoming southwest in the afternoon.

    High: 52 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 34. Southwest wind 7 to 10 mph becoming east northeast after midnight. Winds could gust as high as 18 mph.

    Low: 34 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 57.

    High: 57 °F

    Sunny

The Last Word

Thank you for another successful season. Our success is directly related to support from our community and the Forest Service. Thanks to the readers of the forecast, everyone that sent in observations, took an avalanche class, or donated money, time or gear. We will issue conditions updates on Mondays and Fridays through April.

GENERAL SPRING SNOWPACK AND TRAVEL ADVICE

Spring weather can be highly variable and create a mix of avalanche problems. Snow conditions and stability can change drastically from day to day or hour to hour. Anticipate rapid change and plan accordingly. Abundant snowfall over the winter with more spring snow to come makes avalanches possible into summer.

NEW SNOW AND WIND LOADED SLOPES

Spring storms are notorious for depositing heavy amounts of snow in the mountains. Even with a deep and generally stable snowpack throughout the advisory area, heavy and rapid loads of new snow will decrease stability. The main problems to look out for are avalanches breaking within the new snow, wind slabs, and loose snow avalanches. The likelihood of triggering an avalanche spikes during and immediately after snowstorms. New snow instabilities tend to stabilize quickly, but it’s a good idea to give fresh snow a day to adjust before hitting big terrain. New snow instabilities can be challenging to assess, and spring storms bond to old snow differently across aspects and elevations. Conservative terrain selection is essential during and immediately following storms. Avoid wind-loaded slopes and slopes steeper than 35 degrees for 24-48 hours after new snow and wind.

New snow can quickly change from dry to wet on a spring day, and stability can decrease rapidly with above freezing temperatures or brief sunshine. New snow may bond well early in the morning and then easily slide later. Wet loose slides are likely during the first above freezing temperatures or sunshine immediately after a storm. Anticipate changes in snow stability as you change aspect or elevation and over the course of the day. An early start is always an advantage. Be ready to change plans or move to safer terrain at the first signs of decreasing stability.

WET SNOW AVALANCHES

Spring and wet snow avalanches go hand-in-hand. Above freezing temperatures, rain, and/or intense sunshine cause the snow to become wet and weak and make wet avalanches easy to trigger or release naturally. Conditions tend to become most unstable when temperatures stay above freezing for multiple days and nights in a row. Avoid steep terrain, and be aware of the potential for natural wet avalanches in steep terrain above you, if you see:

  • Heavy rain,
  • Above freezing temperatures for more than 24 hours,
  • Natural wet avalanches,
  • Rollerballs or pinwheels indicating a moist or wet snow surface,
  • Or if you sink to your boot top in wet snow.

In general, if the snow surface freezes solid overnight, the snowpack will be stable in the morning and stability will decrease through the day as snow warms up. The snow surface hardness, rate of warming, duration of sunshine, aspect and elevation determine how fast stability will decrease through the day. Be aware that sunny aspects may have a wet snow avalanche danger while shadier slopes still have a dry snow avalanche danger. Getting off of steep slopes should be considered when, or before, the above signs of instability are present. Wet snow avalanches, whether loose snow or slabs, can be powerful, destructive and very dangerous. Conservative terrain choices, starting early in the day, and careful observations can keep you safe. See Alex’s recent video, and this article for more spring travel advice.

CORNICES

Cornices along ridgelines are massive and can break under the weight of a person (photo). Prolonged above freezing temperatures and rain make them weaker and possible to break naturally. They can break off suddenly and farther back than one might expect. Cornice falls can also entrain large amounts of loose snow or trigger slab avalanches. Stay far back from the edge of ridgelines and minimize exposure to slopes directly below cornices. Regardless of whether a cornice triggers a slide or not, a falling cornice is dangerous to anyone in its path.

DISCLAIMER

It does not matter if new snow falls or not, avalanches will continue to occur until the existing snowpack is mostly gone. Always assess the slope you plan to ride with diligence and safety in mind. Do not let your guard down. Travel with a partner, carry rescue gear and only expose one person at a time in avalanche terrain.

Have a safe and enjoyable spring and summer!

Mark, Alex, Ian and Dave

For more spring travel advice see this article from our GNFAC forecaster blog.

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