Several cities in the U.S. Northeast experienced an unusual flip-flop weather phenomenon with an April that was colder than March, climatologists say. Data released by the Northeast Regional Climate Center at Cornell University showed 12 cities in New York, Pennsylvania, Virginia and West Virginia had colder average temperatures in April than in March. In five of the cities it was the first time the phenomenon had occurred since record keeping started, a Cornell release reported Tuesday. \"March 2012 was a record-breaking month, breaking more than 15,000 temperature records across the United States,\" Jessica Rennells, a climatologist at the Northeast Regional Climate Center, said. \"A month later, March\'s heat is still breaking records. March was warmer than April at 12 of our first-order stations,\" she said. \"This is the first time for this to happen at Dulles (Va.), Scranton (Pa.), Buffalo, Rochester, Syracuse and Binghamton (N.Y.) since their record keeping began.\" Erie, Pa., and Ithaca, N.Y., each experienced such a weather juxtaposition just once before, both in 1946, the center reported.