While it appears to be related to several mini-strokes she had suffered recently, she says the parting is "amicable." Her final broadcast, after more than twenty years at WGN-TV, is projected to be in September.
http://www.suntimes.com/news/foster/6831904-417/allison-payne-leaving-wgn-channel-9.html
http://www.suntimes.com/news/foster/6831904-417/allison-payne-leaving-wgn-channel-9.html