From a D-League press release:

NEW YORK, Jan. 22, 2010 - Due to inclement weather in North and South Dakota, the NBA Development League today announced changes to the schedule for Saturday, Jan. 23 and Sunday, Jan. 24.

The Tulsa 66ers will remain in Sioux Falls following tonight's game to play a second contest against the Skyforce tomorrow, Jan. 23 rather than traveling to play the Wizards in Bismarck.

The Los Angeles D-Fenders will remain in Bismarck following their game tonight to play on Sunday, Jan. 24 rather than traveling to play the Skyforce in Sioux Falls.

The originally scheduled games between the D-Fenders and Skyforce (Jan. 23) and 66ers and Wizards (Jan. 24) have been cancelled.

By incelement weather, they mean what the North Dakota governor has decided is a "snow emergency."

Tulsa has a bit of history with this type of situation, unfortunately.  I'm glad they changed the schedule around - definitely no reason to have a disaster like this happen again.