Collapse of the polar vortex, as was experienced in January 2018, can bring severe cold to the northern U.S.

• A. False
• B. True
• C. Not possible
• D. Sometimes true

Answer: (B)

When the polar vortex weakens or becomes disrupted, the cold air that normally circles near the poles can spill far south into North America. The vortex acts like a dam holding the Arctic chill in the high latitudes; if it loosens, the jet stream often buckles into larger north-south waves, allowing frigid Arctic air to move into Canada and the northern United States, producing severe cold spells.

January 2018 is a real example of this pattern. A weakened and disturbed vortex led to an amplified jet stream with deep troughs over North America, bringing extreme cold to many northern states and breaking temperature records in several places.

So, the statement is true because this disruption is a recognized mechanism for delivering severe cold to the northern U.S. It’s not just a rare fluke; historical events show that such polar-vortex disruptions can and do bring bitter air southward.