The photos below show a Chinook Arch Cloud over Calgary Alberta Canada. Chinooks are only created in a few geographical locations on earth. The Arch Cloud and warm winds are created by distant coastal winds, adiabatic warming of downward moving air coming of the leeward (eastern) Rocky Mountains. The local natives called these warm Chinook winds "snow eater" as that is exactly what they do. A strong Chinook can melt all our ground snow in one day. It's not uncommon for Calgary, Alberta winter temperature to rise within 30 degrees in a matter of hours. The record Chinook temperature rise within 24 hours was on January 15, 1972, in Loma, Montana, the temperature rose from -48°C (-56°F) to 9°C (49°F). In 1962 Pincher Creek ( 200km south of Calgary), the temperature rose by 41°C (from -19°C to 22°C) in one hour. Chinook winds can obtain speeds in excess of hurricane force 120km. The most powerful recorded Chinook wind was 171km in Lethbridge, Alberta. Trains have been known to be derailed in this area. During the winter, driving can be treacherous as the wind blows snow across roadways sometimes causing roads to vanish and snowdrifts to pile up higher than 1 meter. Empty semi trucks driving along Highway 3 and other routes in southern Alberta have been blown over by the high gusts of wind caused by Chinooks. City driving can also be treacherous when rising temperatures melt snow and ice on the roads. The streets become very dirty and windshield wiper fluid is a must. Long time Calgarians rarely get caught with no wiper fluid. Strong Chinooks are usually followed by more bad weather and snow fall. See this interesting site for Calgary Seasons photographs.