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A Hard(er) Rain's A-Gonna Fall

  • By AMS Staff
  • Mar 9, 2023

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“What we found is pretty simple: When it rains now, it rains more.”

— Daniel Horton of Northwestern University, on a new study that found rainfall in much of the United States has gotten more intense in recent decades. Horton and Ryan Harp, also of Northwestern, utilized data from NOAA’s Global Historical Climatology Network to compare precipitation during two time periods (1951–80 and 1991–2020) and within 17 distinct climate regions of the United States that represented various climates, vegetation, and ecosystems. They found that in much of the eastern, southern, and midwestern United States, precipitation intensity increased, with about 5% more precipitation falling east of the Rocky Mountains in recent decades compared to the earlier period. Changes in the western United States were more varied. Harp noted the study, which was published in Geophysical Research Letters, revealed that precipitation intensities “are becoming more variable as well, making water resource management even more challenging.” The researchers hope their findings could lead to more flood-resistant infrastructure. “You don’t need an extreme weather event to produce flooding,” Horton says. “Sometimes you just need an intense rainstorm. And if every time it rains, it rains a little bit more, then the risk of flooding goes up.” [Source: Northwestern University]

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