A report by Climate Central has identified a rise in conditions that support severe thunderstorms in the United States, attributing it to changes in "convective available potential energy" (CAPE), a measure of atmospheric instability that contributes to the development of thunderstorms with potential to produce tornadoes, damaging winds and hail. The most significant increases occur during the traditional severe weather season from April through September. The increase in thunderstorm potential is strongest across parts of the Midwest, Ohio Valley and South. Thunderstorm wind speeds in the central U.S. have increased by about 7 percent for every 1 degree Fahrenheit of warming between 1980 and 2020. In the Northeast, trends are more variable but still trending upward overall. The report also noted that there are modest increases in instability in some inland areas, especially east of the Cascades.