Changes in extreme, cold-season synoptic precipitation events under global warming

We analyze regional climate model (RCM) simulations of daily, spatially distributed extreme precipitation events, using co-operative network observations and output from 10-year RCM simulations of present and future-scanario climates. We examine an Upper Mississippi River basin region during October-march for daily amounts that exceed the 99.95th percentile and that occure simultaneously at several observation sites or model grid points. For the observations and each simulation, nearly all such extreme regional events occur when a slow moving, cut-off-low system develops over the Rockies and Great Plains and steadily pumps moisture into the Upper mississippi region form the Gulf of Mexico. The threasold for the extreme events increases int eh future scenario by an amount similar to the increase in saturation specific humidity. The results suggest robust circulation behavior for such extremes in the face of climate change. Citation: Gutowski, W.J., Jr., S. S. Willis, J.C. Patton, B.R.J. Schwedler, R.W.Arritt, and E.S. Takle (2008), Changes in extreme, cold-season synoptic precipitation events under global warming, Geophys. Res Lett., 35, L20710, doi:10.1029/2008GL035516.