A polar vortex is currently hitting the United States, with schools closed in many areas and at least four deaths caused by treacherous conditions.

The National Oceanic and Atmospheric Administration's Space Weather Prediction Center prediction map is showing that ... goes down in parts of the northern United States, according to the ...

The National Oceanic and Atmospheric Administration's Space Weather Prediction Center prediction map is showing that ... goes down in parts of the northern United States, according to the ...