Tornado Alley
It has also been asserted that there are numerous Tornado Alleys. In addition to the Texas/Oklahoma/Kansas core, such areas include the Upper Midwest, the lower Ohio Valley, the Tennessee Valley and the lower Mississippi valley. Some studies suggest that there are also smaller tornado alleys located across the United States.
List of tornadoes in the tornado outbreak of May 18–21, 2013
The severe threat shifted towards damaging straight-line winds on May 21 as a large squall line developed across the southern states. Further north in Ontario, three tornadoes, including an EF2, touched down. Over the following five days, the system responsible for the outbreak moved very little across the Eastern United States. By May 24, it virtually stalled off the coast of New England, resulting in several days of heavy rain across the region. It later moved northeastward and was last noted by the Weather Prediction Center late on May 26 over southeastern Canada. During the storm's eleven-day trek across the United States, it produced at least 60 tornadoes, four of which were rated EF3 or higher. Over 1,000 reports of damaging winds were received by the Storm Prediction Center as well. The system's slow movement also resulted in record-breaking rains in North Dakota, New York, and Vermont. Additionally, during the overnight of May 25 – 26, unusually cold air behind the cyclone resulting in record-late snows across northern New England.