The National Weather Service is reporting 49.32 inches of total rainfall at a site southeast of Houston, which now marks the greatest accumulation of rainfall ever recorded in the contiguous United States on account of a single tropical storm.
This latest rainfall figure still needs to be verified by other sources, but it’s likely to hold—and even increase—given that Harvey is in the midst of making its third landfall, where it’s expected to dump even more rain on the already waterlogged states of Texas and Louisiana. The record 49.32 inches was recorded this morning in Mary’s Creek at Winding Road, besting the previous record if 48 inches.
According to reporting by the Washington Post, Texas state climatologist John Nielsen-Gammon recorded 50.4 inches of rainfall midday today at a site 40 miles (65 km) east of Houston.
Harvey’s total concentrated rainfall, says Nielsen-Gammon, is 19 times the daily discharge of the Mississippi River—the most of any tropical system ever recorded. This tremendous amount of precipitation has fallen onto an area measuring 20,000 square miles, much of it now underwater. Prior to Harvey, the wettest tropical cyclone in US history came in 1978 with the landing of tropical storm Amelia in Medina, Texas.
Harvey has been called a “one in 500 years storm,” but the Space Science and Engineering Center at the University of Wisconsin at Madison says this event has a probability rating of 0.1 percent for Texas, or a “one in 1,000 years” storm. But as WaPo pointed out earlier today, Houston is experiencing its third of these supposed “500 year events” in three years. So either Houston is incredibly unlucky, or the the climate models are in need of serious revision.