PITTSBURGH - The National Weather Service has issued a tornado watch for much of western Pennsylvania.

The watch is in effect from about 3:30 p.m. to 9 p.m. Wednesday. It is in effect for Adams, Allegheny, Armstrong, Beaver, Bedford, Blair, Butler, Cambria, Fayette, Franklin, Fulton, Greene, Huntingdon, Indiana, Somerset, Washington and Westmoreland counties.

A watch means that weather conditions are favorable to produce funnel clouds or a tornado.