BALTIMORE — The polar vortex is expected to split into two pieces early next week, one over Canada and one over Siberia. All 50 European model members now show the vortex winds flipping direction by November 14. That would be a record-early stratospheric warming, about two weeks ahead of the old November 28 record. For Maryland, the change could set the stage for colder air by late November and early December.
What the Polar Vortex Is
The polar vortex is a ring of strong winds about 20 miles above the Arctic. It normally spins tightly around the North Pole. When it is strong, it keeps the coldest air bottled up near the pole.
When the vortex weakens or splits, that cold air can break loose. Pieces of the vortex may drift south over North America, Europe, or Asia. That can open the door to colder weather weeks later.
Model Shows Two Separate Pieces
A forecast map of the stratosphere shows the vortex split into two centers. One deep cold center sits over eastern Canada, close to the northern United States. The other sits over the Arctic near Siberia.
Winds around the vortex at 60 degrees north are shown at about -0.8 meters per second. A negative number means the winds have reversed, blowing the opposite way. The gap between the two pieces is shown at about 64 decameters.
No Instant Cold Blast
This is not an instant blast of cold air. The effects of a vortex split usually take 2 to 4 weeks to reach the surface. Weather on the ground will not change right away…