Nov 5, 2016

Synoptic and quantitative attributions of the extreme precipitation leading to the August 2016 Louisiana flood

S.‐Y. Simon Wang, Lin Zhao, Robert R. Gillies
Geophysical Research Letters
  • States that the catastrophic August 2016 flood in the U.S. state of Louisiana was a result of intense precipitation produced by a slow‐moving tropical low‐pressure system interacting with an eastward traveling baroclinic trough to the north
  • States that while tropical‐midlatitude interactions of this nature are rare, they are not unprecedented
  • Analyses presented point toward the tendency for more and perhaps stronger upper level troughs propagating out of the western U.S. in summer; these then have an increasing potential to cross paths with low‐pressure systems that form around the Gulf Coast
  • Finds that, combined with the projected increase in precipitable water, resulting precipitation magnitude would increase
  • Large‐ensemble modeling indicates that the prospect of future tropical‐midlatitude interactions is a scenario that Louisiana will face in the future
  • Regional simulations estimate that the climate warming since 1985 may have increased the event precipitation (11–14 August 2016) on the order of 20%, all of which allude to a conceivable forecast of nonhurricane‐related, warm season extreme precipitation in the Gulf Coast states