The purpose of Part I of this research is to build on previous studies by increasing the knowledge of the surface and instability patterns associated with violent tornadoes. Also, Part I presents the similarities and differences of the patterns across separate geographic regions of the United States. For this study, 38 violent United States tornado episodes including 70 violent tornado tracks were considered from 1993 to 1999. Surface observation maps and synoptic weather maps from the initialized ETA model have been examined to recognize the patterns associated with the violent tornadoes. Surface low pressure, surface dewpoint, low-level boundaries and centers of maximum CAPE (Convective Available Potential Energy) have been analyzed on synoptic maps. In addition, instability and low-level moisture parameters have been analyzed. As a result, surface synoptic and mesoscale patterns favorable for violent tornadoes are presented for different geographic regions of the United States.