Being able to forecast mountain weather is a crucial skill when traveling or living in mountainous terrain. Wether you’re deep in the backcountry, at a ski resort, completely lost, driving over a mountain pass, or chillin’ in a backcountry cabin, it’s important to understand what the skies are telling you about the coming weather. If you are deep enough in the backcountry, being able to forecast mountain weather could save your life.
Below are a few tips that will help us all forecast mountain weather. Weather is always very unpredictable and these tips aren’t 100% fool-proof, but these are good tools to keep in you brain.
Mountains cover 25% of the Earth’s land surface, contain 26% of the global population,
and produce 32% of the surface runoff (Meybeck et al. 2001). – Michael P. Meyers, NOAA/National Weather Service, Grand Junction, Colorado
HOW TO PREDICT MOUNTAIN WEATHER:
1. Check the Weather Forecast Before Heading Out.
Always check the weather before you head out on a trip. This is easy to do and can give you enormous insight into what precipitation and temperatures will be like on your trip. Weather forecasts aren’t always accurate and you may be out longer than a forecast is viable. Nevertheless, this is a good place to start.
2. Reading the Skies – Cloud Formations
Reading the sky is likely the single most important component of predicting mountain weather.
A. Lenticular clouds (see above image) indicate strengthening winds and moisture laden air. The appearance of lenticular clouds generally mean that a storm will be approaching in the next 6-24 hours.
B. High, wispy cirrus clouds can be a signal of condensing moisture and these clouds very often increase in the sky before a weather event. Cirrus clouds can mean bad weather is coming within 24-36 hours. Cirrus clouds are often followed by lower clouds that will bring precipitation your way. Once those lower clouds arrive you may only have 6 or so hours before precipitation begins to fall. When these high clouds cover the sky they create a “milky” sky. This milky sky combined with strong winds is a strong signal that a storm is headed towards you.
C. Thunder Clouds (Cumulonimbus) clouds are clearly a sign of weather. You’ll have to determine wind direction to see if those thunder clouds are headed your way. In the mountains, in the summertime, it is very normal for thunderclouds to build via daytime heating and orographic lifting and drop precipitation and lighting on mountains at around 2-5pm in the afternoon. In the summer, you don’t want to be on mountaintops in the afternoon.
Learn more cloud formations and their weather consequences: Forecasting Weather Using Clouds
3. Ring Around the Sun of Moon:
A ring around the sun during the day or the moon at night indicates that there is moisture in the air and it’s that moisture that is creating that ring. That moisture is cirrostratus clouds that are often associated with warm weather fronts. These rings often signal a storm approaching within 72 hours.
“Circle around the moon, rain or snow soon.”
5. Red Sky at Morning:
“Red sky at night, sailor’s delight; Red sky at morning, sailors take warning.”
In the mountains, it’s often difficult or impossible to see the horizon due to mountains blocking your view. Yet, mountain climbers and skiers are often on high peaks at sunrise. If you can see the western horizon at sunrise and you see red clouds in the sunrise, this is a very simple way of knowing that there are clouds headed your way. These clouds could be bringing precipitation to you.
3. Dropping Air Pressure:
This will only work if you have brought a pocket barometer with you. If you did, you see the air pressure falling sharply, that’s a huge indicator that a storm is headed your way. Low air pressure = a weather front is approaching (rising in elevation will also drop the air pressure so make sure to take that into account).