Northeast U.S. Mechanisms of Cold-season Hydroclimate Variability and Change in Observations and Models

Precipitation projections in the mid-latitudes indicate seasonal shifts and changes in extreme events. Early and late boreal winter precipitation modes and variability for the Northeast U.S. are examined through observational and reanalysis data. Mechanisms behind observed changes in cold season precipitation are examined through EOF and least squared regression methods. The historical experiments from 16 CMIP5 models are then evaluated to discern if the models are able to simulate the processes underlying cold season variability. We also examine model projections, which have suggested a shift towards more late winter precipitation, and discuss how a process-based evaluation of models might add insight into credibility of projections.