Continued hot, dry conditions and a potential for increased fire activity have prompted Yellowstone National Park to reinstate fire restrictions and close some hiking trails and backcountry campsites. Visitors are urged to check with rangers and watch for closure signs. Because of the forecast for continued hot and dry conditions, Yellowstone is reinstituting limited fire restrictions, effective noon tomorrow. Among those restrictions, campfires are allowed only in established fire grates or fire rings in picnic areas or campgrounds. The use of portable charcoal grills is prohibited. When in the back country, any fire which can produce an ash is prohibited. Smoking is prohibited along all trails and anywhere in the backcountry and is allowed only in vehicles and along roads, near buildings, and in developed campgrounds or picnic areas if you are standing in an area at least three feet in diameter where nothing on the ground will burn. On the other hand, portable stoves and lanterns that use propane, white gas, kerosene or jellied petroleum may be used with caution anywhere in the park. Park officials point out that there have been 11 fires reported in Yellowstone this year of which four were human caused.