Sidney Montana Police Dept., Associated Press
In this undated photo provided by the Sidney, Mt., Police Dept. shows Sidney High School math teacher Sherry Arnold, 43, who has been missing since Saturday, Jan. 7. Hundreds of people are assisting in the search for the Sidney teacher who did not return home after going for a jog on Saturday Jan. 7, 2012.

BILLINGS, Mont. — Authorities say they will search one more day for missing Montana teacher Sherry Arnold, who left her home for a pre-dawn run and never returned.

All that's been seen of her since Saturday morning is a single running shoe by a ditch.

Sidney Mayor Bret Smelser says search teams Tuesday will re-canvass areas around town, looking for any more clues to the 43-year-old woman's disappearance. After that, any searches will be based on leads developed by local law enforcement and the FBI, which is assisting the case.

Snow and rain is expected Tuesday and temperatures are expected to plunge into the teens by nightfall.

Hundreds of volunteers have helped in the search for Arnold, a native of the town of about 5,000 along the North Dakota border.