A polar vortex split high in the stratosphere is expected to send frigid Arctic air toward Michigan and the Great Lakes in late March and early April. This event could bring colder-than-normal temperatures and late frosts to the northern U.S. Michigan and Great Lakes are expected to see another cold snap later this month, with temperatures expected to drop to single digits in places. This is not the same event as the "final collapse" of the polar vortex, which occurs when spring air begins to warm temperatures over the Arctic. Experts warn that polar vortex events are often overhyped and that the impact on surface weather depends on several factors such as the direction of the Polar jet stream, moisture moving off the oceans and fast-moving clipper systems.