A relentless heat wave is sweeping across the western and southern United States, placing more than 39 million people under heat alerts as temperatures climb to life-threatening levels. Weather officials say the powerful "heat dome" responsible for days of extreme conditions has shifted west, where it is expected to strengthen further before expanding into additional states … [Read more...] about Heat wave scorches U.S. with 39 million under alerts as temperatures reach 119°F for a second day