Updated

Strong winds are whipping wildfires in northwest Nebraska that have roughly tripled in size despite firefighters' efforts.

Officials estimated Sunday that the fires have now burned roughly 273 square miles, including at least 27,000 acres in South Dakota. That's up from roughly 93 square miles on Saturday and more than twice the size of Omaha.

The outlook was improving earlier Sunday because cooler weather overnight helped firefighters make good progress against the West Ash and Douthit fires near Chadron.

But then the Wellnitz fire north of Rushville broke through its containment lines. That fire has burned roughly 136 miles itself and was about 20 percent contained Sunday afternoon.

The West Ash fire is about 45 percent contained. The Douthit is about 95 percent contained.