The most potent blast will enter the north-central U.S. on Friday, the National Weather Service warned, before roaring across much of the rest of the nation over the weekend. Arctic air will ...

40S. YES, IT IS TURNING MILDER, BUT IT IS GOING TO BE A BRIEF LITTLE WARM-UP COMING OUR WAY THIS WEEKEND BECAUSE AFTER A FRONT GOES BY, THE DOOR IS OPENING UP FOR A NEW BLAST OF ARCTIC AIR.