A major winter storm hitting Northern California with rain and snow was expected to intensify Monday and bring travel headaches and the threat of localized flooding after an especially warm and dry fall in the U.S. West. Kari Hall, Kris Sanchez, Cierra Johnson and Mike Inouye report. Stay connected: Follow us on Twitter: http://www.twitter.com/nbcbayarea Like us on Facebook: http://www.facebook.com/nbcbayarea Follow us on Instagram: http://www.instagram.com/nbcbayarea Add us on Snapchat @NBCBayArea Catch up on all the day's news: http://www.nbcbayarea.com Download our app: On iOS: http://nbcbay.com/R1BhqYM On Android: http://nbcbay.com/rUcA97h