AUSTIN (KXAN) -- A polar vortex has the potential to bring extremely cold temperatures to much of the lower 48 states. It is "a large area of low pressure and cold air surrounding both of Earth’s poles," according to the National Weather Service. A counter-clockwise flow of cold air in the stratosphere forms the "vortex." Undisrupted polar vortex- stable cold air in the Arctic In winter, the polar vortex can weaken and destabilize, causing it to dip southward and sending cold air into the mid-latitudes. This disruption also allows milder air to flow northward into the Arctic. Disrupted polar vortex- cold-snap of air moves south, milder air moves north When the weakened polar vortex interacts with moist air in the mid-latitudes, it can lead to wintry weather. In Central Texas, there have been several instances of prolonged cold snaps, bringing sub-zero temperatures, ice storms and heavy snow. It's crucial to stay prepared during the winter months, as Arctic air could return to the Lone Star State this winter.