Colorado State University (CSU) Atlantic Hurricane Season Forecast Dr. Philip Klotzbach of Colorado State University (CSU) has issued his April forecast for the 2018 Atlantic Hurricane Season. The forecast calls for 14 named storms, 7 hurricanes and 3 major (Category 3+) hurricanes between the months of June and November. With the release of the forecast, Dr. Klotzbach is predicting slightly above average tropical cyclone activity in the Atlantic Basin during the upcoming 2018 season. The report cites several factors as to why slightly increased activity is being forecast. One such main factor regards the eventual transition of ENSO (El Niño-Southern Oscillation) from current La Niña conditions to ENSO-neutral. Sea surface temperatures over the tropical Pacific have been warming since November 2017 and upper-ocean heat content is currently above normal. The statistical and dynamical forecast models continue to show a wide range of outcomes regarding the state of ENSO by the peak development months (August, September, October). Roughly one-third of the models are calling for ENSO-neutral conditions by late summer/fall, with the rest of the model suite forecasting a weak El Niño. CSU s best guess estimate at this time is that ENSO-neutral conditions will be present by the peak of the Atlantic hurricane season. A second factor revolves around current sea surface temperatures across the North Atlantic Ocean. At present, there are cold anomalies in the far North Atlantic, near-normal temperatures in the eastern tropical Atlantic, and warm anomalies off the east coast of the United States. Dr. Klotzbach says that this type of pattern is a mixture of signals typically seen in both a positive (warm) and negative (cool) phase of the Atlantic Multidecadal Oscillation (AMO). Much of the cooling can be attributed to a strong positive phase of the North Atlantic Oscillation (NAO) that allowed strong trade winds to cause increased mixing, upwelling, and evaporation. However, the pattern changed around March 1, and slight warming has since commenced as the NAO shifted negative. As an addendum, Dr. William Gray pioneered seasonal hurricane forecasting and countless landmark hurricane research while at Colorado State University. He issued the first Atlantic Hurricane season forecast in 1984. Dr. Gray remained active in the field until his passing in April 2016. The tables on the next page show the CSU forecast, including probabilities of landfall on the United States mainland. The full report is available at CSU s Tropical Meteorology webpage (http://tropical.atmos.colostate.edu/). The next forecast update is expected Thursday May 31, 2018. Risk. Reinsurance. Human Resources.
CSU Atlantic Basin Hurricane Season Forecast (June 1 November 30) Forecast Parameter Median Year (1981-2010) 2018 Named Storms 12.0 14 Named Storm Days 60.1 70 Hurricanes 6.5 7 Hurricane Days 21.3 30 Major Hurricanes 2.0 3 Major Hurricane Days 3.9 7 Accumulated Cyclone Energy (ACE) 92 130 Net Tropical Cyclone Activity 103% 135% Source: Colorado State University CSU Major Hurricane Landfall Probabilities (June 1 November 30) Forecast Parameter Average Year 2018 Entire U.S. Coastline 52% 63% U.S. East Coast (including FL Peninsula) 31% 39% U.S. Gulf Coast (FL Panhandle to Brownsville, TX) 30% 38% ***Expected 52% risk of major hurricane tracking into the Caribbean (average is 42%) Source: Colorado State University Colorado State University (CSU) Atlantic Hurricane Season Forecast 2
About Aon Benfield Aon Benfield, a division of Aon plc (NYSE: AON), is the world s leading reinsurance intermediary and fullservice capital advisor. We empower our clients to better understand, manage and transfer risk through innovative solutions and personalized access to all forms of global reinsurance capital across treaty, facultative and capital markets. As a trusted advocate, we deliver local reach to the world s markets, an unparalleled investment in innovative analytics, including catastrophe management, actuarial and rating agency advisory. Through our professionals expertise and experience, we advise clients in making optimal capital choices that will empower results and improve operational effectiveness for their business. With more than 80 offices in 50 countries, our worldwide client base has access to the broadest portfolio of integrated capital solutions and services. To learn how Aon Benfield helps empower results, please visit aonbenfield.com. Copyright by Impact Forecasting No claim to original government works. The text and graphics of this publication are provided for informational purposes only. While Impact Forecasting has tried to provide accurate and timely information, inadvertent technical inaccuracies and typographical errors may exist, and Impact Forecasting does not warrant that the information is accurate, complete or current. The data presented at this site is intended to convey only general information on current natural perils and must not be used to make life-or-death decisions or decisions relating to the protection of property, as the data may not be accurate. Please listen to official information sources for current storm information. This data has no official status and should not be used for emergency response decision-making under any circumstances. Cat Alerts use publicly available data from the internet and other sources. Impact Forecasting summarizes this publicly available information for the convenience of those individuals who have contacted Impact Forecasting and expressed an interest in natural catastrophes of various types. To find out more about Impact Forecasting or to sign up for the Cat Reports, visit Impact Forecasting s webpage at impactforecasting.com. Copyright by Aon plc. All rights reserved. No part of this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise. Impact Forecasting is a wholly owned subsidiary of Aon plc. Colorado State University (CSU) Atlantic Hurricane Season Forecast 3
Tropical Storm Risk (TSR) Atlantic Hurricane Season Forecast Tropical Storm Risk (TSR), which is part of Aon Benfield Research s academic and industry collaboration, has issued its April forecast for the 2018 Atlantic Hurricane Season. TSR s Professor Mark Saunders and Dr. Adam Lea are forecasting 12 named storms, 6 hurricanes and 2 major (Category 3+) hurricanes between the months of June and November. This is a reduction from TSR s initial projection of tropical activity released in December 2017. The projected activity is expected to be 15 percent below both the long-range norm since 1950 and the recent 2008-2017 norm. The report specifies two primary factors as to why a slightly below normal hurricane season is now being forecast. The main reason is that TSR now expects ENSO-neutral conditions to be present by the summer and/or autumn of 2018. This is in line with current consensus ENSO outlooks by both the dynamical and statistical models. Due to this expectation, TSR notes that this will have an increasing effect of stronger trade winds over the Caribbean Sea and tropical North Atlantic from the July to September time period. This would mean increased wind shear and a resultant negative impact on cyclogenesis. TSR also believes such a trade wind pattern would lead to cooler sea surface temperatures in the tropical North Atlantic and Caribbean Sea. The agency stresses that atmospheric and oceanic uncertainties remain for the upcoming season, and forecast skill for sea surface temperature and trade winds at this timeframe is low. Drs. Saunders and Lea currently project that there is a 27% probability that the 2017 Atlantic Hurricane Season ACE Index will be above-average, a 33% likelihood it will be near-normal, and a 40% chance it will be below-normal. The Accumulated Cyclone Energy Index is equal to the sum of the squares of 6-hourly maximum sustained wind speeds (in knots) for all systems while they are at least tropical storm strength. The ACE Landfall Index is the sum of the squares of hourly maximum sustained wind speeds (in knots) for all systems while they are at least tropical storm strength and over the United States mainland (reduced by a factor of 6). The tables on the next page show the TSR forecast and the range of uncertainty that surrounds the forecast. The full report is available at TSR s webpage (http://tropicalstormrisk.com/). The next forecast update is expected in early June 2018. Risk. Reinsurance. Human Resources.
TSR Atlantic Basin Hurricane Season Forecast (June 1 November 30) Forecast Parameter Average Year 2018 (December 2017) 2018 Named Storms 11 15 12 Hurricanes 6 7 6 Major Hurricanes 3 3 2 ACE Index (1950-2016) 101 117 84 Source: Tropical Storm Risk TSR U.S. Landfalling Atlantic Hurricane Season Forecast (June 1 November 30) Forecast Parameter Average Year 2018 Named Storms 3 2 Hurricanes 1 1 ACE U.S. Landfall Index (1950-2016) 2.3 1.5 Source: Tropical Storm Risk Tropical Storm Risk (TSR) Atlantic Hurricane Season Forecast 2
About Aon Benfield Aon Benfield, a division of Aon plc (NYSE: AON), is the world s leading reinsurance intermediary and fullservice capital advisor. We empower our clients to better understand, manage and transfer risk through innovative solutions and personalized access to all forms of global reinsurance capital across treaty, facultative and capital markets. As a trusted advocate, we deliver local reach to the world s markets, an unparalleled investment in innovative analytics, including catastrophe management, actuarial and rating agency advisory. Through our professionals expertise and experience, we advise clients in making optimal capital choices that will empower results and improve operational effectiveness for their business. With more than 80 offices in 50 countries, our worldwide client base has access to the broadest portfolio of integrated capital solutions and services. To learn how Aon Benfield helps empower results, please visit aonbenfield.com. Copyright by Impact Forecasting No claim to original government works. The text and graphics of this publication are provided for informational purposes only. While Impact Forecasting has tried to provide accurate and timely information, inadvertent technical inaccuracies and typographical errors may exist, and Impact Forecasting does not warrant that the information is accurate, complete or current. The data presented at this site is intended to convey only general information on current natural perils and must not be used to make life-or-death decisions or decisions relating to the protection of property, as the data may not be accurate. Please listen to official information sources for current storm information. This data has no official status and should not be used for emergency response decision-making under any circumstances. Cat Alerts use publicly available data from the internet and other sources. Impact Forecasting summarizes this publicly available information for the convenience of those individuals who have contacted Impact Forecasting and expressed an interest in natural catastrophes of various types. To find out more about Impact Forecasting or to sign up for the Cat Reports, visit Impact Forecasting s webpage at impactforecasting.com. Copyright by Aon plc. All rights reserved. No part of this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise. Impact Forecasting is a wholly owned subsidiary of Aon plc. Tropical Storm Risk (TSR) Atlantic Hurricane Season Forecast 3