I've searched my Mac for that file and can't find it.. I'm guessing that file has to do with a third-party weather app. Have you tried searching in Finder to see if there's a copy of that file elsewhere on your system? If you find that file there's a chance you might be able to open the associated third-party app and see if there's a problem somewhere. It may be a third-party weather app is deleting the daily forecast file each day to keep them from accumulating on your system.