( CNN ) -- As it continued its northward retreat , the arctic blast still held sway over the upper Midwest , where it bore down with below-zero lows early Thursday . This should be its last stand in the United States , as temperatures bump up day by day , the National Weather Service said . Minnesota 's coldest spots were forecast to plunge to as low as minus-30 degrees Fahrenheit with a frost-biting wind chill factor near 40 below . Most of the nation should drop below freezing overnight , according to the NWS . Pipe bombs . The polar vortex left behind ticking time bombs of sorts , and as it gives way to warmer weather , they are going off . Pipes that froze and cracked are unfreezing , and plumbers and fire crews are rushing to stop the gushing water leaks , CNN affiliates are reporting . The spurts caused some serious damage to homes and businesses and flooded streets . Leaking pipes that broke during the freeze closed down a 30-story office building in Kansas City , Missouri , after its basement flooded , taking down central electrical circuits , KMBC reported . More than 50 apartments were damaged when pipes broke in a building in Chattanooga , Tennessee . Phones rang hot at plumbing companies from Memphis to Decatur , Alabama . `` Good for business . Bad for sleep , '' Decatur plumber Chris Byrd told WAAY . `` It 's about a once-every-10-year event we get something like this . '' It 's so cold , humor edition . Slippery slopes . The changing weather is laying down thin ice patches from western Tennessee to eastern Kansas and Oklahoma , the weather service warns . As warmer air moves in , it is bringing rain , drizzle and fog , which are bumping up against temperatures still below freezing . The result is what the NWS calls a `` wintry mix '' -- everything from freezing fog to snow . It will ice over streets , but slicken bridges and overpasses in particular and possibly tear down some power lines , the weather service said . It 's another nasty leftover from the polar vortex , which authorities have blamed for as many as 23 deaths across six states .
The upper Midwest still sees lows around minus-20 . The low is below freezing in most of the nation . Pipes are thawing and bursting , damaging homes and businesses . The changing weather is laying down a slick spot from the Midsouth to Oklahoma .