Reading the Weather: How to Use History, Experience, and Forecasting to your Advantage

reading the weather: how to use history, experience, and forecasting to your advantage

by Elias Zane-Holt

Weather! What a dynamic and ethereal thing. As I sat down to share my thoughts with you all, I had two key epiphanies. First, I think we tend to underestimate the impact of weather on our daily lives. Weather is constantly affecting our mood, and swaying our critical choice making each day– from deciding what to wear, to where to go. Second, it affects all of us. We share the burdens and blessings of weather; we experience both the awesomeness of it and the bogusness of it. Weather is a series of events that can change in a matter of minutes, hours, days, weeks, and longer. It is created and builds in what we call the troposphere (the closest layer of the atmosphere to earth’s surface), and it descends. A good forecast, especially on a day where our objective is weather dependent, is the ideal– a stress free, all smiles, expedition (at least in relation to the weather). However, if the weather is forecasted to be bad, or turns gnarly unexpectedly, this can throw a wrench in the best of plans.. So, how do we avoid all this stress? It’s simple: research, assess, and forecast weather. We need to stack the odds in our favor and get the best data to make the best choices when it comes to being in the mountains. I think of the weather in three categories: what happened (research), what is happening (assessing), and what is going to happen (forecasting).

What happened?

Depending on the season and your objective, it is important to know weather history in your area of interest. This is especially important if you are in the mountains and dealing with snow. First, you will want to know if the weather history in a specific area had an impact on your snowpack. This will inform you of avalanche danger, and other potential concerns. Unfortunately, most common weather websites and apps might not give detailed weather history in the areas you’re looking for– this can be attributed to either data storage concerns, or a general lack of demand in less populated areas. If you’re as invested in weather as me, though, you’ll keep your own detailed spreadsheet of the weather in your most frequented areas. If you aren’t quite so dedicated, I recommend sites like The National Weather Service.

Another reason we should be interested in weather history is that it helps with weather prediction. For the most part, weather will work in predictable patterns. During specific seasons, and sometimes with certain climatic events, patterns can appear. Specifically, mountainous areas may have patterns that are characteristic of the area. In the areas that I often take clients to ski, I have a historical log of weather patterns that I update after each expedition.This record allows me to use previously published data in addition to my own experience. For example, I have ski guided in Antarctica for the past 4 years, and have tracked the wind pattern through the Drake Passage. These winds are predominantly blowing from the west, and are most intense around Cape Horn. Historically, we see a pattern of low pressure systems that form in the Pacific and travel west to east across the passage. Recognizing this pattern helps me think ahead to predict snowpack for upcoming expeditions, and overall forecasting! In short, tracking the weather in a particular area in the weeks leading up to your climb will help maximize your window of success.

What is happening?

You’ve checked the weather (and avalanche forecast!) religiously in the weeks leading up to your trip. Your packs have been tetris-ed into your car’s trunk/footwell/passengers laps. Maybe you’ve even made it to the base of your climb! And you’re forecasted perfect weather is… not. In this situation, it is key to tune into the “nowcast” and adjust your expectations accordingly. All the factors you took into account when picking this window come into play again, to ensure that you’re climbing safely. You’ll need to reassess, and make a call about whether to adjust your game plan.

What is going to happen?

Now let’s dive into the juicy stuff: forecasting. There are many ways to go about forecasting, but I prefer to look at the weather in two different views: Micro and Macro. Micro is small scale local weather information. It pertains to questions like will it rain on this area of x mountain, and if so how much today? Or will we see an inversion in temperatures with our elevation gain? Macro, on the other hand, is what this industry calls the “big picture.” Macro level questions are about larger weather trends. What is the predicted weather for the local area on a large scale? Should I expect to see a pressure system moving through my area any time soon, and if so for how long? Should I prepare for big wind events coming from the southwest?

You can look at either of these two views in whichever order you like. I personally like to start with the Macro first, and follow with the micro picture. In examining both, I get an idea for what is happening now, and what is coming– in the next few hours and next few days. Resources for studying weather at each scale are readily available, from resources like NOAA or MountainWeather.

Unfortunately, one caveat with forecasting is that it can be very WRONG. I know, it’s frustrating. However, there is a tactic that stacks the odds in your favor. Go back to looking for patterns, but this time gather information from multiple prediction, data, or forecasting platforms (and your trusty weather history). Each resource will give you the basics: wind, cloud cover, precipitation, and temperatures. Gather information from all the (reputable) sources you can find for your desired area, and look for patterns. A good rule of thumb is that if 3 of 5 models agree, there’s a higher likelihood that the forecasted weather would happen– rather than if one app alone calls for a particular weather event.

In the mountain guide industry we commonly say terms like “module agreement.” This means that we are looking for multiple modules (or all of them) agreeing on a given forecast. These modules might not agree on everything: they might agree on an amount of forecasted precipitation, but not when it’s coming. However, being thorough and taking multiple sources into account will be your best bet when making sense of upcoming weather.

Let’s talk about where I like to find all of this good weather stuff:

For Macro (websites)- I like to look at Windy, Mountain Weather Lite, NOAA, and wunderground.

For Micro (models) I like to look at the GFS (Global Forecast System), ECMWF (European Center for Medium-range weather forecasts), NAM (North American Mesoscale) and HRRR (high resolution rapid refresh).

So there you have it folks, a crash course in researching, assessing, and forecasting weather so that you can adjust your mountain adventure expectations and objectives. Play around with all of these models and check out the weather history for your area! You might be surprised by what you find.

Enjoy,
Elias

If you want to hear more from Elias, check out his webinar on planning a backcountry tour. He’ll even show you his preferred weather apps, and how he uses them.

Backcountry Tour Planning Webinar & Trip Planning Tools

Timelapse of yearly weather on Rainier provided by NPS:

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