University of Arizona



University of Arizona (UA) Forecasts an Active Hurricane SeasonKyle Davis and Xubin Zeng6/12/2020The University of Arizona (UA) forecasting team updated their April predictions and still reach the same conclusion: an active year is expected in 2020. Our models predict the following:2020 June Prediction70% Probability Range2020 April PredictionMedian Since 1980Hurricanes119 to 12107Major Hurricanes43 to 552Named Storms1715 to 191913ACE166140 to 192163102Our total predicted tropical activity is well above the median since 1980 in all four categories. One of the most important aspects in our models is the March/April/May average sea surface temperatures (SSTs) in the tropical Atlantic, which are the warmest since 2010. The Atlantic Multidecadal Oscillation (AMO) index - another measure of Atlantic SSTs and directly used in our ACE forecast – has been very warm throughout most of the year, though has dropped a little over the last month, yet still remains high The El Ni?o Southern Oscillation (ENSO), represented by the Multivariate ENSO Index (MEI), was not factored in as the AMO index was greater than zero (please see references below for more detail on how our model is constructed). We also did not factor ENSO into either the major hurricane or ACE predictions since the Atlantic is so warm, giving storms a better chance at breaking through barriers that El Ni?o may present. The index currently shows neutral conditions and global models are mostly showing these conditions are likely to prevail throughout the season.The Atlantic zonal pseudo-wind stress also indicates favorable activity for hurricanes, but slightly tempers the outlooks for major hurricanes, named storms, and ACE since we analyze different regions for those variables. Since we started issuing predictions for tropical cyclone activity in 2014, our average errors have been quite similar to the errors published in both Davis et al. (2015) and Davis and Zeng (2019). For hurricanes, our average prediction error is 1.8 hurricanes. For ACE, since we started issuing forecasts in 2017, our average error has been 33 units. Our major hurricane model – for which we also started issuing predictions in 2017 - has actually never been off in all three years we have issued forecasts. And finally, for named storms, 2019 was the first year we issued predictions, and our error was two storms. This uncertainty is reflected in the probability ranges in the table above.Reference: Kyle Davis, Xubin Zeng, and Elizabeth A. Ritchie, 2015: A New Statistical Model for Predicting Seasonal North Atlantic Hurricane Activity. Wea. Forecasting, 30, 730–741, doi: 10.1175/WAF-D-14-00156.1 Davis, K. and X. Zeng,?2019:?Seasonal Prediction of North Atlantic Accumulated Cyclone Energy and Major Hurricane Activity.?Wea. Forecasting,?34,?221–232, contact: Mr. Kyle Davis (email: davis7000@); Prof. Xubin Zeng (email: xubin@email.arizona.edu; Tel: 520-621-4782) ................
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