New Hampshire officials are advising visitors to the White Mountain National Forest to plan ahead. With Memorial Day Weekend approaching, officials are expecting a number of campers and hikers. But they ask that people take into account the region’s unpredictable weather. Rain, snow, and fog are possible any time of the year. Also, visitors are warned not to rely on cellphone s, which have limited coverage in the mountains. With the arrival of the emerald ash borer in Concord, there are also concerns over invasive insects being carried to the area on firewood brought from home. Campers should buy their firewood locally, officials said.