New modeling research in the Proceedings of the National Academy of Sciences by Paul O'Gorman at MIT and Tapio Schneider at Caltech have refined modeling data with regards to increasing global temperatures and the expected resulting rainfall theories.  Rather than rising in lock-step with rising water vapor concentrations, the frequency of heavy rainfall events in the mid-latitudes rises somewhat less than the rate of the moisture capacity of the atmosphere. 

Extreme rainfall events rise about 6 per cent for every degree Celsius increase in global average temperatures, the researchers report.  This is a significant statistic when paired with the authoritative warming estimates of 3.5 to 7.4 degrees Celsius during century. In the Forecast, More Heavy Rain by John D. Cox | August 18, 2009  Source

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