Fig. 3. Flood damages increase exponentially with AR category.

(A) The Ralph et al. AR scale (20) classifies ARs into five categories depending on IVT and duration. For example, an AR with a peak IVT of 800 kg m⁻¹ s⁻¹ and a duration of 78 hours is classified as a category 4 or extreme AR. (B) NDJFM flood damages increase exponentially with AR category: Vertical scale is logarithmic; black bars are medians; boxes are 25th and 75th percentiles, and whiskers are 5th and 95th percentiles; dots are extrema; numbers in parentheses are the number of NDJFM events in each category. Note that the total number of ARs in the Gershunov AR catalog (1603) is greater than the number of ARs over the sample period using the Ralph et al. AR scale (1134), which classifies events with a duration of less than 24 hours as non-ARs.