STAMPS@CMU presents:

Unscrambling ensemble simulations to improve hurricane forecasts

by Jenni Evans (Department of Meteorology and Atmospheric Science and Institute for Computational and Data Sciences, Pennsylvania State University)

Online webinar December 4, 2020 at 1:30-2:30 PM EDT.
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In November 2020, Hurricane Iota made landfall in Nicaragua, 15 miles south of where Hurricane Eta had crossed the coast less than 2 weeks earlier. Like Eta, Iota was a Category 4 hurricane at landfall, with maximum sustained winds near 155 mph. In a situation like Eta or Iota, devastation follows landfall due to a combination of winds, rainfall, flooding and mudslides. The storm’s ultimate impact relies on its track, its intensity and its structure. An accurate hurricane forecast can save countless lives. In the drive to produce accurate hurricane forecasts, meteorologists developed detailed deterministic models and refined them endlessly, but large forecast errors still occurred. Modelers began running permutations of the deterministic models 10s, or even 100s, of times. These ensemble simulations of hurricane evolution provide a measure of the uncertainty in the forecast, but translating this into a forecast can mean that much information is lost. I will discuss how we can synthesize the information in the ensemble objectively, and show that the resulting partition distinguishes between different synoptic situations, preserving information on the sources of the uncertainty in the forecast. Examples will be drawn from two US landfalling hurricanes: Hurricane Sandy (October/November 2012) and Hurricane Harvey (August 2017).


Jenni L. Evans is the Director of Penn State’s Institute for Computational and Data Sciences (ICDS), Professor of Meteorology & Atmospheric Science and served as Centennial President of the American Meteorological Society (AMS) in 2019. Evans earned both her undergraduate and doctoral degrees in applied mathematics at Monash University. The Institute for Computational and Data Sciences (ICDS) is a pan-university research institute and is also the home of Penn State’s high performance computing facility. ICDS jointly employs over 30 tenure track faculty and supports researchers across the disciplinary spectrum.
Dr. Evans was the Centennial President of the American Meteorological Society in 2019, is Fellow of the American Association for the Advancement of Science and also of the American Meteorological Society. She has served on numerous national and international committees and has long been Meteorologist in an interdisciplinary team of scientists and actuaries advising the State of Florida by auditing catastrophe risk models for hurricanes and flood.

Evans’ research spans tropical climate, climate change, and hurricane lifecycles in the tropics, as well as hurricanes that undergo “extratropical transition” (like Hurricane Sandy in 2012) and sonification – the “music of hurricanes.” She uses high performance computing for simulations of hurricanes, and machine learning and advanced statistical techniques, to study formation of hurricanes in the tropics and subtropics, methods for improving hurricane forecasts, theory for the limiting intensity of hurricanes and how this could change with climate change, and the use of climate models to understand the impacts of climate change on our daily lives.