Using Self Organizing Map Transition Matrices as a Forecast Tool

Some extreme weather events, such as the early season heavy snow and cold weather outbreak of early November 2014, can be traced back to the influence of tropical or extratropical cyclones on the planetary scale flow. Such planetary scale reorganization also occurs in conjunction with serial extratropical cyclogogenesis. Potential temperature on the dynamic tropopause (defined by the 2 PVU surface) combined with equivalent potential temperature at 850 hPa, allows for a dynamically complete characterization of the flow. CFSR Reanalysis data spanning 31 years are used to provide these measures, and Self-Organizing Maps (SOM) are then constructed to identify precursor and concurrent regimes in which such cyclogenesis events occur. Key elements of this analysis are the transitions between SOM regimes, which provide a means for identifying increased regime predictability at medium and extended ranges. Details of these findings will be presented.