Tynan is a 1991 magna cum laude graduate of Washington and Lee University, from which she earned a degree in journalism and politics. She holds American Meteorological Society television seal number 1099.

She came to WPVI from KTNV in Las Vegas, Nevada, where she worked as a weather and news anchor for "Good Morning Las Vegas." Prior to that, she was the weekend weather anchor and a general assignment reporter for WDBJ in Roanoke, Virginia.

At WPVI, she started out as a weekend weathercaster and general reporter. Then she became the weekday morning weathercaster. When Dave Roberts cut back his duties in 2003, she became the weathercaster for weeknights at 5:30 and 11 p.m. After Lisa Thomas-Laury went on medical leave, Tynan took over as co-host of several locally produced specials, including the 6 ABC Boscov's Thanksgiving Day Parade, the 4th of July Parade, Philly on Wheels, and the Flower Show. Although not officially announced, when Dave Roberts retired in late 2009, Tynan became the chief weathercaster/meteorologist of the station.

Her salary is rumored to be $600,000 a year. After divorcing her first husband, school teacher Michael Badger, she remarried to divorcee Greg Watson and gave birth to a baby boy named Luke on January 20, 2006, and a girl named Emma Grace on September 17, 2007.

Tynan is also an accomplished triathlete and frequently runs marathons. She was featured on the February 2001 cover of Runner's World magazine.