J. Climate http://doi.org/c6xb (2019).
Nearly half of all Atlantic tropical cyclones turn into extratropical cyclones as they move poleward. This process is called extratropical transition (ET), and some of the most destructive recent Atlantic hurricanes underwent such a conversion. Hurricane Irene, in 2011, was one such example, but how ET for storms like this might change in a warmer world is still an open question.
Chunyong Jung and Gary Lackmann, of North Carolina State University, USA, used Weather Research and Forecasting (WRF) model experiments integrated at various levels of complexity to compare Irene’s observed ET to its equivalent in a warmer climate. They found that in a high-end warming scenario, the storm featured substantially heavier precipitation owing to increased moisture convergence and ocean evaporation, and ET was more intense due to lower pressure at the storm’s centre and stronger surface winds. Importantly, ET lasted about 60% longer, meaning the storm travelled a greater distance north as it transitioned. This result implies that a warmer world may change ET in a way that lures tropical cyclone-like conditions — and the havoc they wreak — further poleward.
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Langenbrunner, B. Further poleward influence. Nat. Clim. Chang. 9, 499 (2019). https://doi.org/10.1038/s41558-019-0522-9