Saint Elias Mountains

Precipitation and storms

Cyclonic storms tracking in off the Gulf of Alaska strike the coastal wall of the range and are forced abruptly upward, releasing some of the heaviest precipitation recorded anywhere in North America; annual snowfall across the range's icefields has been described as exceeding that received anywhere else on the continent.^[10] Downstream of the peaks, the town of Yakutat receives an average of about 151 inches (3,840 mm) of precipitation and more than 200 inches (5,100 mm) of snow each winter, with numerous storms and high winds accompanying the wet spring, autumn and winter seasons.^[12] Modelled precipitation data compiled by the Alaska Climate Research Center suggest that the unmonitored high country southeast of Yakutat, where moist Pacific air is forced over the range's steep coastal front, may receive upward of 450 inches (11,400 mm) of precipitation a year, which would place it among the wettest locations on Earth.^[13][14]

This orographic effect sustains the range's icefields, the most extensive glaciated system outside the polar regions. Research combining in-situ snow accumulation data with back-trajectory modelling has found that high-intensity Gulf of Alaska storms deposit heavy snowfall across the entire Saint Elias–Alaska Range region simultaneously, whereas lower-intensity systems are largely blocked by the coastal wall and reach the continental interior only through gaps in the mountains, such as the Alsek River valley.^[15][10]

These storms have also made the range notorious among mountaineers for sudden, violent weather. Systems can arrive within hours and pin climbers in place with sustained hurricane-force winds and zero visibility; in June 2015, three experienced mountaineers descending Mount Logan were trapped for more than a week by winds estimated at 160 km/h (100 mph), surviving by hand-digging a snow cave into a crevasse.^[16] Parks Canada's climbing-permit application for the range's icefields warns applicants to prepare for storms, high winds, zero visibility, and temperatures below −40 °C (−40 °F); between 1973 and 2015, roughly 4,000 climbers and skiers visited the icefield ranges, of whom 15 died.^[17]

Temperature

The two sides of the range differ almost as sharply in temperature as in precipitation. The Kluane Front Ranges and other areas within the range's rain shadow experience a dry, cold continental climate with long, severe winters, while the coastal slopes remain comparatively mild but are rarely dry.^[11]

At high elevation, the cold becomes extreme even by subarctic standards. On the roughly 5,000-metre (16,000 ft) summit plateau of Mount Logan, the highest peak in Canada and second-highest in North America, average air temperatures fall to about −45 °C (−49 °F) in winter and remain around −27 °C (−17 °F) even at the height of summer, with the plateau not known to rise above freezing at any time of year.^[18][19][20] These conditions make the summit plateau one of the very few non-polar sites where ancient annual snow layers survive undisturbed by summer melt, preserving a climate record that in one ice core has been traced back roughly 20,000 years, drilled from a site between Prospector and Russell peaks.^[19] Extreme low-temperature readings on the mountain have been reported in the range of −77 °C (−107 °F), a figure mountaineering sources describe as among the coldest air temperatures ever recorded outside Antarctica, though it was taken at very high altitude and is not counted among official lowland temperature records for Canada or North America.^[21][22]