A Clipper System is a fast-moving winter weather phenomenon that impacts large portions of North America, known for its swift passage and intense cold. These systems are a recurring feature of the winter season, typically sweeping across the continent from Canada to the Eastern Seaboard. While they may not always bring the heaviest snowfalls, their reputation comes from the combination of strong winds and a dramatic plunge in temperature that follows their track.
Defining the Clipper System
A Clipper System is a compact, low-pressure weather system that develops and tracks across southern Canada and the northern United States. The most common form is the “Alberta Clipper,” which originates on the lee side of the Canadian Rockies near the province of Alberta. This formation results from a process called lee side cyclogenesis, where descending westerly air flow over the mountains causes pressure to drop and generate a small surface disturbance. Although Alberta is the most frequent starting point, these systems can also develop further east, sometimes earning regional nicknames like the “Manitoba Mauler.”
The entire system is powerfully steered by the polar jet stream, which provides the upper-level forcing necessary for the cyclone to organize and intensify. As the low-pressure center moves, it pulls frigid Arctic air masses south and east across the continent. Because the system forms in a cold, dry environment and moves quickly, it is often described as “moisture-starved” compared to large coastal storms. This reliance on upper-level dynamics and temperature contrast defines the Clipper’s structure and subsequent weather impact.
Signature Weather Patterns
The weather delivered by a Clipper System is characterized less by deep snow accumulation and more by wind and cold. The snow that falls is typically light and powdery, often accumulating in the range of 8 to 15 centimeters (3 to 6 inches) over a short period. This modest snowfall is due to the system’s low moisture content and its rapid movement, which limits the time precipitation can fall in any single location.
The most impactful element is the powerful wind associated with the system’s passing. Strong wind gusts, sometimes reaching 65 kilometers per hour (40 miles per hour), can lead to widespread blowing and drifting snow, even with minor accumulations. This combination of wind and light snow can quickly reduce visibility and create localized blizzard conditions. Following the passage of the low-pressure center, a dramatic surge of colder air from the Arctic sweeps in, causing rapid temperature drops. Temperatures often fall by 10 to 20 degrees Celsius (18 to 36 degrees Fahrenheit) in less than twelve hours. This frigid air, combined with the strong winds, produces dangerously low wind chill values.
Speed and Trajectory Across the Continent
The name “Clipper” is a direct reference to the swift sailing ships of the 19th century, acknowledging the system’s characteristic speed. These weather systems move quickly, often traveling at speeds between 50 and 60 kilometers per hour (30 to 40 miles per hour). This rapid movement is the primary reason the weather impact, including the snowfall, is typically short-lived, with the entire event lasting only a few hours in any given location.
The common trajectory of a Clipper System begins by tracking southeastward from its origin in the Canadian Prairies into the northern United States. It typically moves through the Upper Midwest and the Great Lakes region before progressing toward the Eastern Seaboard. A path across the Great Lakes can occasionally introduce more moisture into the system, which may increase snowfall totals or spark intense lake-effect snow downwind of the lakes. The consistent northwest-to-southeast path makes the Clipper a highly predictable, though transient, feature of winter weather.