where do tornadoes most commonly occur in the us
east of the Rocky Mountains
title: Tornadoes in the United States text: Tornadoes in the United States Tornadoes are more common in United States than in any other country. The United States receives more than 1,200 tornadoes annually—four times the amount seen in Europe. Violent tornadoes—those rated EF4 or EF5 on the Enhanced Fujita Scale—occur more often in the United States than in any other country. Most tornadoes in the United States occur east of the Rocky Mountains. The Great Plains, the Midwest, the Mississippi Valley and the southern United States are all areas that are vulnerable to tornadoes. They are relatively rare west of the Rockies and are also less frequent title: Tornadoes in the United States text: The tornado was generated by the same storm system that delivered a devastating tornado to the town of Flint, Michigan. Areas further south – notably Pennsylvania and Maryland – and areas to the west of the Appalachians are more vulnerable to tornadoes. NCDC figures for the period 1950 to 2006 show that Pennsylvania reported 697 tornadoes, followed by New York State (358), Maryland (269), Massachusetts (153), New Jersey (144), Maine (101), New Hampshire (86), Connecticut (82), Delaware (58), Vermont (37), Rhode Island (9), and the District of Columbia (1). The worst tornado outbreak in the Northeast occurred in Pennsylvania on title: Tornado climatology text: Tornado climatology Tornadoes have been recorded on all continents except Antarctica and are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as well as the strongest and most violent tornadoes. A large portion of these tornadoes form in an area of the central United States popularly known as Tornado Alley. Other areas of the world that have frequent tornadoes include significant portions of Europe, South Africa, Philippines, Bangladesh, parts of Argentina, Uruguay, and southern and southeast Brazil, northern Mexico, New Zealand, and far title: Tornadoes in the United States text: the United States can occur at any time, they are most common in spring and least common in winter. Because spring is a transitional period for the climate, there are more chances of cooler air meeting with warmer air, resulting in more thunderstorms. Tornadoes can also be spawned by landfalling tropical cyclones, which usually occur in late summer and autumn. In the United States, thunderstorms capable of producing tornadoes usually form when the temperature is at its highest, typically from 4:00 p.m. to 7:00 p.m. Although the period in which most tornadoes strike ("tornado season") is March through June, tornadoes title: Tornado climatology text: yearly than any other country and reports more violent (F4 and F5) tornadoes than anywhere else. Tornadoes are common in many states but are most common to the west of the Appalachian Mountains and to the east of the Rockies. The Atlantic seaboard states – North Carolina, South Carolina, Georgia and Virginia – are also very vulnerable, as well as Florida. The areas most vulnerable to tornadoes are the Southern Plains and Florida, though most Florida tornadoes are relatively weak. The Southern United States is one of the worst-affected regions in terms of casualties. Tornado reports have been officially collated