As part of an ongoing company-funded research study of tornadic risk assessment, by means of the Site Assessment of Tornado Threat (SATT) software, Engineering Analysis Inc. (EAI) has determined the rankings of the top twenty tornado-prone states for the month of July. The rankings, based on National Weather Service data from 1950 through 1997, are as follows:
Disturbed Land Rank State Probability Fraction Area (Acres) 1 Maryland 4.02 · 10-5 253 2 Illinois 3.22 · 10-5 1146 3 Nebraska 3.15 · 10-5 1544 4 Wisconsin 2.63 · 10-5 916 5 Iowa 2.56 · 10-5 918 6 Minnesota 1.93 · 10-5 982 7 Ohio 1.89 · 10-5 496 8 New Jersey 1.85 · 10-5 88 9 Massachusetts 1.73 · 10-5 87 10 Michigan 1.57 · 10-5 573 11 New York 1.56 · 10-5 473 12 Kansas 1.50 · 10-5 785 13 Connecticut 1.43 · 10-5 45 14 Pennsylvania 1.35 · 10-5 389 15 South Dakota 1.28 · 10-5 623 16 Wyoming 9.75 · 10-6 605 17 Vermont 9.43 · 10-6 56 18 Indiana 8.66 · 10-6 199 19 North Dakota 8.45 · 10-6 375 20 Delaware 6.74 · 10-6 8The "probability fraction" represents the average fraction of land area within the boundaries of the state disturbed by tornadoes during July for the 48-year period from 1950 through 1997. The "disturbed land area" represents the average number of acres of land within the boundaries of the state disturbed by tornadoes during July for the same 48-year period.