Tool Users: Modern Weather Forecasts

On August 21, 1935, German climbers Max Sedlmayr and Karl Mehringer set off in clear weather to make the first serious attempt on the North Face of the Eiger, a notoriously grim, icy wall below a 3967-meter summit in the Swiss Alps. The pair ascended steadily the first day, but they slowed on the third day. Apparently, they’d underestimated the technical difficulty of a rockband and an icefield. On the third night, a thunderstorm blasted the face with rain and snow. Their decision to continue, through two more days of snowfall and heavy clouds, caused the attempt to turn from unlucky to tragic.

Observers noted the pair ascending until August 25, when they became completely obscured by another storm. The site where they perished is known as the Death Bivouac. At the time, members of the Swiss and British mountaineering establishment condemned the Germans’ alleged disregard for their own lives. But when you examine the events closely, Sedlmayr and Mehringer’s failure to retreat seems more of a miscalculation than a death wish. With the limitations of forecasting in 1935, they couldn’t have known just how bad the weather would become until they were trapped.

By the early 1900s, scientists had already begun to compile measurements of atmospheric conditions such as air pressure and wind speed into mathematical models to try to create extended forecasts. But they concentrated their efforts on predicting weather in residential areas, rather than atop isolated peaks. Even today, the high altitudes and complex topographies of mountains create additional levels of unpredictability for climbers and meteorologists alike. Alpinists travel through layers of different weather and climate zones on their way up a big peak. Like rocks in a swift river, the protruding forms of summits can alter the direction and intensity of wind currents, changing the nature of weather systems as they move through a range.

To mitigate the risks of getting trapped up high in an unexpected maelstrom, many twentieth-century climbers relied on siege tactics: fixing ropes and establishing multiple camps to ensure easier and faster retreats to shelter in case the weather turned. Yet these slow and heavy methods also maximized the duration of time they spent on big mountains, increasing the likelihood of suffering the accumulative effects of altitude.

During the 1970s and 1980s, cutting-edge alpinists increasingly shifted to fast and light techniques, which tended to have less impact on the environment. Minimalism came to represent the hallmark of “good style” (in some ways a return to an earlier era of alpinism). In the 1990s and early 2000s, more reliable and accessible forecasts supercharged this transition. With high-resolution satellite imagery, meteorologists could produce more accurate and specific reports, while the Internet and other forms of modern communications technology allowed climbers to receive their predictions even on remote peaks.

Rather than merely hoping that the weather would hold during risky summit bids, twenty-first-century alpine-style climbers can plan ascents and descents around particular, forecasted windows. “When you know for damn sure that the next several days are going to be absolutely perfect, who’s going to bother fixing ropes up something you know you can do more rapidly?” American alpinist Kelly Cordes says. “It makes it way easier to embrace this fast and light ethos.”

In the summer of 2019, when Mark Richey, Steve Swenson, Chris Wright and Graham Zimmerman set out to make the first ascent of Link Sar, a 7041-meter peak in an isolated region of the Pakistan Karakoram, Wyoming-based meteorologist Jim Woodmencey sent them regular updates via satellite phone and text messages. For July 31, he delivered a prediction of two calm days followed by approximately thirty-six hours of storms and then another period of good weather. Based on that information, the climbers planned to leave advanced base camp, ascend to a bivouac at 6200 meters, wait out the storms, and then make their final summit push and descent during a longer stretch of clear skies.

Weather reports, however, are not a replacement for solid preparation and situational awareness. “The forecast you get is guidance, not gospel,” cautions Woodmencey. When the Link Sar team left the 6200-meter camp after thirty-six hours, they didn’t experience the clear weather Woodmencey had anticipated. Instead, just 200 meters higher, they had to make another, emergency bivouac in an ongoing storm. There, they waited again until the weather window finally arrived before they could continue to the summit. It was the team’s knowledge of the mountain and their adaptability that kept them safe.

While the science of meteorology advances, climbers still need skills to cope with uncertainties. “On crowded high-altitude peaks,” Cordes writes, “we’ve seen how unexpected weather events can lead to mass disaster. But lower, more technical destinations are surely not immune. In Patagonia’s Chalten Massif, forecasts are relatively new and incredibly accurate because of its unique topography–yet the storms remain violent. One of these days the forecast will be wrong and catch a bunch of people unprepared, with devastating effects. It’s part of the unpredictability of the world.”

[Graham Zimmerman’s story about the first ascent of Link Sar can be found here. This Tool Users story originally appeared in Alpinist 72, which is now available on some newsstands and in our online store.–Ed.]