Tropical Cyclone Outer Size Impacts the Number and Location of Tornadoes

There remains no consensus on whether the outer size of the tropical cyclone (TC) wind field impacts tornado occurrence. This study statistically examines the relationship between TC outer size with both the number and location of tornadoes using multidecadal tornado reports, a reanalysis‐derived TC outer size metric, and radiosonde data. These results show that larger TC spawn tornadoes that are located farther from and over a broader region relative to the cyclone center, although these changes do not entirely scale with TC outer size. Larger TCs are also associated with more frequent occurrence of tornadoes per 6 h, especially enhanced numbers of tornadoes. These changes in tornado occurrence in larger TCs may be due to a broadening of favorable helicity for tornadoes in the downshear sector, which may be partially offset by CAPE reductions in the left‐of‐shear quadrants. Plain Language Summary Tropical cyclones (TCs) (also known as tropical depressions, storms, and hurricanes) with similar landfall locations and maximum wind speeds often spawn different numbers of tornadoes. One understudied factor that may explain these differences in tornado occurrence is how far the TC winds extend from its center, referred to as its outer size. This study investigates whether the outer size of the TC wind field impacts the number and location of tornadoes using tornado and TC observations, historical weather forecast data, and observations from balloon‐borne weather instruments. These results show that larger TCs more frequently spawn tornadoes, which are associated with a broader region of tornado occurrence. Moreover, tornadoes tend to be located farther from the TC in storms with larger wind fields. These results are attributed to a broader set of radii with favorable vertical variations in wind speed and direction for tornadoes in larger TCs. These changes may be partially offset by reductions in temperature and moisture that may explain why the changes in tornado frequency and location are not more extreme in larger TCs. Together, these results suggest that the outer size of the TC is a key factor in forecasting tornadoes. Key Points Tornadoes occur farther from and over a broader region relative to the center of larger tropical cyclones (TCs) Larger TCs more frequently spawn enhanced numbers of tornadoes per 6‐h period Larger TCs are associated with broader regions of favorable convective‐scale kinematic environments for tornadoes