Circumglobal teleconnection and early summer rainfall in the US Intermountain West
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Physical processes responsible for the abnormally wet condition in the Central Intermountain West (CIW) of the United States in June 2009 were investigated. It was illustrated that persistent rainy conditions over the CIW during June 2009 were associated with a pronounced circumglobal teleconnection pattern, which is characterized as a short Rossby wave train along the jet stream waveguide with a wave number 5 structure. The ascending motion and moisture flux convergence over the CIW associated with the cyclonic action center over the US West Coast in the teleconnection wave train could be essential for the persistent local rainfall during June 2009. Further analysis suggested that the June 2009 circulation pattern is consistent with a prevailing mode of the summer circumglobal teleconnection pattern. The findings in this study provide information for improved understanding of the early summer rainfall regime in the CIW.
KeywordsGeopotential Height Rossby Wave Empirical Orthogonal Function Precipitation Anomaly Water Vapor Flux
This study was supported by the USDA CSREES-funded Drought Management, Utah Project and by the Utah Agricultural Experiment Station, Utah State University, and approved as journal paper number 8164. XJ acknowledges support by NOAA CPPA program under Award NA09OAR4310191. Discussion with T.-C. Chen regarding the stationary short-wave train was much appreciated.
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