Colorado State University (CSU) Atlantic Hurricane Season Forecast

Transcription

1 Colorado State University (CSU) Atlantic Hurricane Season Forecast Dr. Philip Klotzbach of Colorado State University (CSU) has issued his latest forecast for the Atlantic Hurricane Season. The forecast calls for 14 named storms, 6 hurricanes and 2 major (Category 3+) hurricanes between the months of June and November. This is a slight reduction from the April forecast, and also includes May s Subtropical Storm Alberto. With the release of the forecast, Dr. Klotzbach is predicting near normal tropical cyclone activity in the Atlantic Basin during the upcoming season. The report cites several factors as to why slightly increased activity is being forecast. One such main factor regards the eventual phase of ENSO (El Niño- Southern Oscillation) during the rest of the hurricane season. Sea surface temperatures have warmed during April and May in the central and eastern tropical Pacific Ocean and ENSO-neutral conditions currently exist. Considerable changes in ENSO often occur during June and July, and statistical and dynamical forecast models are predicting warm-neutral or weak El Niño conditions during the peak seasonal months of August, September, and October. CSU s best guess estimate at this time is that warm 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, the current anomaly pattern is not conducive for an active hurricane season. The pattern currently features cold anomalies in the far North Atlantic, cold in the subtropical eastern Atlantic and extending into the tropical Atlantic, and warm anomalies off the east coast of the United States. The last two months have featured anomalous warming off the U.S. East Coast and cooling along the west coast of Africa. The likely driver of this pattern is an abnormally strong ridge of high pressure draped across the eastern and central Atlantic Ocean. This has helped cause strong trade winds that prompt upwelling, mixing, and enhanced evaporation in the tropical Atlantic. Colorado State notes that if current conditions in the tropical Atlantic persist, or if El Niño develops more quickly than expected, a further reduction in their forecast may be required. However, if the tropical Atlantic begins to warm and the tropical Pacific was to remain neutral, their forecast may need to be increased. Large uncertainties for the season remain. 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 Dr. Gray remained active in the field until his passing in April 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 ( The next forecast update is expected in early August. Risk. Reinsurance. Human Resources.

2 CSU Atlantic Basin Hurricane Season Forecast (June 1 November 30) Forecast Parameter Median Year ( ) (April ) (May ) Named Storms Named Storm Days Hurricanes Hurricane Days Major Hurricanes Major Hurricane Days Accumulated Cyclone Energy (ACE) Net Tropical Cyclone Activity 103% 135% 100% Source: Colorado State University CSU Major Hurricane Landfall Probabilities (June 1 November 30) Forecast Parameter Average Year (April ) (May ) Entire U.S. Coastline 52% 63% 51% U.S. East Coast (including FL Peninsula) 31% 39% 30% U.S. Gulf Coast (FL Panhandle to Brownsville, TX) 30% 38% 29% ***Expected 41% risk of major hurricane tracking into the Caribbean (average is 42%) Source: Colorado State University Colorado State University (CSU) Atlantic Hurricane Season Forecast 2

3 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

4 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 Atlantic Hurricane Season. TSR s Professor Mark Saunders and Dr. Adam Lea are forecasting 9 named storms, 4 hurricanes and 1 major (Category 3+) hurricanes between the months of June and November. This is a significant reduction from TSR s initial projections of tropical activity released in December 2017 and April. TSR says there is a 69 percent likelihood that the projected activity would be in the bottom one-third of Atlantic Hurricane Seasons dating to The report specifies two primary factors as to why a below normal hurricane season is now being forecast. The main reason is that TSR cites the considerable cooling of sea surface temperatures in the tropical North Atlantic Ocean and Caribbean Sea during April and May. This temperature shift is associated with the strengthening of the Azores ridge of high pressure. Additionally, TSR notes that such conditions are likely to enhance stronger-than-normal trade winds in the Atlantic s Main Development Region (MDR) during the peak months of August and September. The agency further explains the expectation of ENSO-neutral or weak El Niño conditions from July to September. This is based on the latest dynamical and statistical model output. However, TSR stresses that there remain sizeable uncertainties in the anticipated phase of ENSO, actual sea surface temperatures, and the strength of vertical wind shear. Each parameter has a direct influence on the number of named storms. Drs. Saunders and Lea currently project that there is just a 7% probability that the Atlantic Hurricane Season ACE Index will be above-average, a 24% likelihood it will be near-normal, and a 69% 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 ( The next forecast update is expected in early August. Risk. Reinsurance. Human Resources.

5 TSR Atlantic Basin Hurricane Season Forecast (June 1 November 30) Forecast Parameter Average Year (December 2017) (April ) (May ) Named Storms Hurricanes Major Hurricanes ACE Index ( ) Source: Tropical Storm Risk TSR U.S. Landfalling Atlantic Hurricane Season Forecast (June 1 November 30) Forecast Parameter Average Year (April ) (May ) Named Storms Hurricanes ACE U.S. Landfall Index ( ) Source: Tropical Storm Risk Tropical Storm Risk (TSR) Atlantic Hurricane Season Forecast 2

6 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