An Arctic outbreak is a meteorological event characterized by a sudden and significant southward movement of frigid Arctic air into lower latitudes, often resulting in extreme cold temperatures, snow, and icy conditions. These events can affect regions far from the Arctic, including the United States, Europe, and Asia.
How Arctic Outbreaks Occur
Arctic outbreaks occur due to interactions between the polar jet stream, Arctic air masses, and other atmospheric dynamics. Here’s a step-by-step explanation:
Arctic Air Accumulation
During winter, frigid air accumulates over the Arctic region, forming a dense, cold air mass known as the Arctic air mass.
This air mass is typically confined to the polar region by the polar vortex, a large, circulating pattern of strong winds in the upper atmosphere that traps cold air near the poles.
Jet Stream Disturbance
The jet stream, a fast-moving current of air high in the atmosphere, acts as a barrier between the colder Arctic air and the warmer air in mid-latitudes.
Disturbances in the jet stream, often caused by warming events in the stratosphere or interactions with mountain ranges and ocean currents, can cause the jet stream to weaken or become wavy.
Polar Vortex Disruption
A sudden stratospheric warming (SSW) event can disrupt the polar vortex, causing it to weaken or split into smaller vortices.
This allows Arctic air to escape southward, where it can flow into regions normally shielded from such extreme cold.
Southward Movement of Arctic Air
Once the jet stream weakens or shifts, Arctic air masses are funneled southward into lower latitudes.
The movement of this cold air is often aided by high-pressure systems over the Arctic and low-pressure systems in lower latitudes.
Examples of Arctic Outbreaks
February 2021 Arctic Outbreak (Texas, USA):
Frigid Arctic air descended as far south as Texas, causing widespread power outages, snow, and record-low temperatures.
Polar Vortex Event (January 2019, USA):
Frigid air engulfed the Midwest, with temperatures dropping below -30°F in some areas.
Beast from the East (2018, Europe):
Cold Arctic air combined with moist air from the Atlantic, causing heavy snow and extreme cold across Europe.
