Twenty-eight people are dead after tornadoes ripped through the southern United States during a weekend of extreme weather that saw other parts of the country hit with either snow, floods or T-shirt weather.The death toll after a storm on the outskirts of Dallas, Texas reached 11, the daily Dallas Morning News reported, citing authorities in two local counties. Among the dead was an infant.Hundreds of people were in emergency shelters due to storm damage to their homes.The Texas fatalities brought the death toll from tornadoes over the long Christmas weekend to 28.Southern states were worst affected by storms that struck Friday, causing flooding in that region. The weather system unleashed several tornadoes in Mississippi, Alabama and other states that officials said killed 17 and destroyed numerous homes on Christmas Day.The youngest victim was a 7-year-old boy, who died when the car he was sitting in was picked up by strong winds.Record-setting warm December temperatures were on the front of the weather system, while ice and sleet are on the other side, forecasters said.The National Weather Service reported up to 60 centimetres of snow Sunday in New Mexico, disrupting travel as many people tried to return home after Christmas celebrations.Unseasonal scenes of people playing beach volleyball in New York's Central Park in 20-degree temperatures on Christmas Eve illustrated the stark contrasts brought on by a weekend of unusual weather.On the other side of the country in and around Washington state, winter sports fans enjoyed optimal skiing conditions.Elsewhere, wildfires in California continued to spread Sunday. The blazes broke out Friday and spread quickly because of winds estimated at about 80 kilometres per hour.