Abstract
The present paper investigates the role played by blocking high systems over Europe in abnormal weather over the Kingdom of Saudi Arabia (KSA) in summer 2010. The NCEP/NCAR Reanalysis data of several meteorological elements such as surface air temperature, wind, sea level pressure, relative humidity, outgoing long wave radiation, precipitation rate, and geopotential height at level 500 hpa) for summer seasons for the period 1948-2012 and in particular of summer 2010 have been used and analyzed through the present work. Furthermore, the corresponding daily and monthly mean values of climatic indices NAO index, SOI, and El-Nino3.4 have been analyzed. The results uncovered that air current in the upper atmosphere over Europe and NAO, SOI and El-Nino3.4 have impacts on the weather conditions over KSA through the study period 1948-2012. During the period of persistence of blocking system over Europe in summer 2010, results revealed that; weather in KSA was fully controlled by two abnormal weather regimes. The first one is the European blocking system and negative anomaly of NAO from the north. The second one is the positive anomaly of SOI and negative anomaly of El-Nino3.4.