MORRISVILLE, N.C. (WNCN) – Frontier Airlines will begin nonstop service in April and May from Raleigh-Durham International Airport to six U.S. destinations. The new airports include New York LaGuardia (LGA), Miami, (MIA), Tampa (TPA), Boston (BOS), Chicago O’Hare (ORD), and Milwaukee (MKE). With the new service, Frontier will…