This infrared-enhanced photo, courtesy of Environment Canada, shows what happens when a tropical storm merges with a cutoff low. Predicted well in advance by the GFS computer model, this cutoff low has formed just east of New England over the last couple of days. When Tropical Storm Nicole moved north, it merged with this upper-level cutoff to create a "stacked," stalled system. Rain bands are backing west through Boston but the system should eventually move east later today.