Duluth, Mn (KDAL)  The recent warm and wet weather has prompted the Duluth Parks and Recreation Department to ask the public to refrain from using city hiking trails, cross country ski trails, the dog park and disc golf course until conditions improve.  The spring thaw has left those areas soft and vulnerable to damage and erosion.  The trails will re-open when the ground dries out and conditions improve.  Meanwhile, the Chester Bowl Ski Hill has closed for the season.