Meteorological Conditions that Initiate Slushflows in the Central Brooks Range, Alaska

Abstract

Over 30 individual slushflows were documented and observations were made of both high and low flow rates during 1979, 1980 and 1981 at Atigun Pass, central Brooks Range. Air temperature, precipitation and global radiation were recorded in 1980 and 1981 during the slushflow season. Meteorological conditions that exist in this arctic alpine environment at the time of break-up apparently are factors that encourage flow activity. Persistent low temperature prior to break-up allows the snowpack to remain intact until late spring. An influx of warm air from the interior of Alaska and long hours of radiation input produce an accelerated rate of snow-melt that plays a major role in slushflow occurrence.

Geomorphic and dendroecological impacts of slushflows in central Gaspe Peninsula (Quebec, Canada)

“…These channels funnel the water supply from snowmelt and precipitation off the plateau and the cirque slopes. The saturation of the snowpack may be exacerbated by a decreasing slope, a situation often reported elsewhere (Onesti 1985;Hestnes and Sandersen 1986;Nyberg 1989;Elder and Kattelmann 1993;Gude and Scherer 1995).…”

“…In addition, 35 cm of snow fell from March 21st to March 23rd followed by 6 mm of rain on March 26th and 3 mm on March 27th. A combination of temperature above the freezing point and rain-onsnow for slushflow triggering has also been observed in Swedish and Finnish Lapland by Hestnes (1985Hestnes ( , 1998, Nyberg (1985Nyberg ( , 1989, and Clark and Seppälä (1988), in Alaska by Onesti (1985), and in Kirgiztan by Elder and Kattelmann (1993). Hétu and Vandelac (1989) have also observed small slushflows on the Gaspé Peninsula, in the Mt St. Pierre area, caused by rainfall on a cover of fresh snow.…”

“…Origin of slushflows Local characteristics play an important role in the formation of slushflow. The slope of Coulée des Mélèzes watershed is exposed to the southeast and receives a high rate of thermal energy, also pointed out elsewhere (Onesti 1985). It also accumulates large quantities of wind-drifted snow along the cirque slopes favourable to snow avalanches and snow creeping.…”

“…Studies on slushflows suggest that weather conditions in the previous 24 hours were important in determining slushflow release (Onesti 1985;Hestnes and Sandersen 1987;Scherer 1994). At the Fig.…”

“…Slushflows are water-saturated snow masses flowing principally along a first-order stream channel. Their formation is associated with increased water content in the snowpack through rainfall, snowmelt or a combination of both until critical instability is reached and snow mass is released (Nyberg 1985;Onesti 1985;Hestnes and Sandersen 1986;Onesti and Hestnes 1989;Hestnes 1998). Slushflows are widespread in arctic and subarctic environments (Washburn and Goldthwait 1958;Rapp 1959Rapp , 1960Rapp , 1962Rapp , 1985Rapp , 1995Nyberg 1985Nyberg , 1989André 1993André , 1995, and also in alpine environments at lower latitudes (Caine 1969;Luckman 1977;Gardner 1983;Elder and Kattelmann 1993).…”