Alberta clipper

An Alberta clipper (also known as a Canadian clipper) is a fast moving low pressure area weather system which generally affects the central provinces of Canada, as well as parts of the Upper Midwest, Great Lakes, and Northeastern United States, precipitating a sudden temperature drop and sharp winds. Alberta clippers take their name from Alberta, the province from which they appear to descend, and from clipper ships of the 19th century, one of the fastest ships of that time.A clipper originates when warm, moist winds from the Pacific Ocean come into contact with the mountains in the provinces of British Columbia and then Alberta. The air travels down the lee side of the mountains, often forming a chinook in Alberta, then develops into a storm over the Canadian prairies when it becomes entangled with the cold air mass that normally occupies that region in winter. The storm then moves east-northeast riding the jet stream, and passes off the upper Atlantic Coast, normally north of Virginia. The storms sweep in at high speed over whatever land they encounter, usually bringing with them sharp cold fronts and drastically lower temperatures. It is not uncommon for an Alberta clipper to cause temperatures to drop by 16 °C (30 °F) in as little as 10 to 12 hours. Often, the storms bring biting winds with them, only increasing the effect of the lower temperatures. Winds in advance of and during an Alberta clipper are frequently as high as 56 to 72 km/h (35 to 45 mph). These conditions would cause wind chill values to drop into the −30 to −45 Celsius (−20 to −50 Fahrenheit) range.Storms beginning their southward treks from other Canadian provinces, far less common than clippers, are often still referred to as clippers, or by the fanciful names Saskatchewan screamer, Manitoba mauler or Ontario scari-o.