ovember 2008 Antigua and Barbuda Meteorological Service

Transcription

1 ovember 2008 Antigua and Barbuda Meteorological Service

2 The Atlantic Hurricane Season Summary 2008 Special Focus on Antigua and Barbuda The Season in Brief Sixteen (16) named storms formed in the Atlantic Basin during Of the 16 storms, 15 formed during the hurricane season and one (1) just prior to the season. Eight (8) storms became hurricanes and five (5) of the eight (8) achieved major hurricane status (category three (3) or higher on the Saffir-Simpson Hurricane Scale). One of these major hurricanes, Hurricane Omar, affected Antigua and Barbuda primarily on October 15 and 16 and caused approximately 18 million US dollars in damage. Overall, tropical cyclone activity caused over 43 billion US dollars in damage and took approximately 933 lives with Hurricane Hanna being the deadliest storm of the year, killing about 537 persons primarily in Haiti (See Table 1). It was a well above normal season with respect to named storms. The season is tied as the fourth most active in terms of named storms and major hurricanes, and is tied as the sixth most active in terms of hurricanes since This is also the first Atlantic season to have a major hurricane form in five consecutive months (July: Bertha, August: Gustav, September: Ike, October: Omar, November: Paloma). On the other hand, in terms of the National Oceanic and Atmospheric Administration (NOAA) of the United States Accumulated Cyclone Energy (ACE) index, which measures the collective strength and duration of named storms and hurricanes, the season was above normal. It had an index of 141, 57% above the median (89.5); the highest since Only 14 other years have recorded higher ACE indices since Omar A run of eight (8) unbroken years of no serious tropical cyclone activity across Antigua and Barbuda was brought to an end by Major Hurricane Omar. The last system to cause similar damage to the islands was Hurricane Lenny of November Omar was a historic tropical cyclone. Since record keeping started in 1851, a tropical cyclone has never formed and intensified into a category four (4) hurricane in the Caribbean Sea, east of 70 degrees west and then move northeast to east-northeast across the Northeast Caribbean. Omar was the fourteenth named storm of the 2008 Atlantic Hurricane Season, the seventh hurricane and the fourth major hurricane. The System formed as a result of the combination of a tropical wave and the Tropical Upper-level Tropospheric Trough (TUTT) on October 13 at 15.4 north latitude and 69.0 west longitude; this is about 488 miles west-southwest of Antigua. At its closest point (from the northwest coast), Omar was approximately 148 miles northwest of Antigua, and 130 miles northwest of Barbuda with maximum sustained winds of 135 miles per hour (mph). However, by definition, the hurricane did not make strike on Antigua and Barbuda; notwithstanding, the islands experienced minimal tropical storm conditions. 1

3 The system caused severe rainfall, which resulted in disastrous flooding. Most of the flooding took place between 0900 and 1600 UTC (5 A.M. and 12 mid day local time) on the morning of October 16, when in excess of five (5) inches of rain fell in most areas. The floods caused significant damage to agriculture and roads; however there were no loss of lives (A full summary on Omar with respect to Antigua is available at the Met Office). Other storms that affected Antigua and Barbuda were: Bertha Bertha became the first hurricane and first of five (5) major hurricanes of the hurricane season. The system formed a couple hundred miles south-southeast of the Cape Verde Islands on July 3 as a tropical depression and became a hurricane on July 7 while centred about 750 miles east of Antigua and Barbuda. Later on July 7 Bertha became a major hurricane on the Saffir/Simpson Scale. The centre of Bertha eventually passed over 400 miles north of Antigua and Barbuda on July 10 as a minimal hurricane (See Map 1). Notwithstanding its distant track from the islands, on July 10, a feeder band from the system spread some showers and thunderstorms across the area. A few of the showers were locally heavy. However, at the V. C. Bird International Airport, Coolidge, these showers only amounted to 8.7 mm or 0.34 inches. The hurricane also caused seas to elevate above six (6) feet during the period July 6 through 9. Fay Fay was the sixth named storm of the hurricane season one (1) of eight storms that did not develop into a hurricane. The system formed near the southeast coast of the Dominican Republic on August 15 (See Map 1). Although Fay did not affect Antigua and Barbuda as a named storm, it caused some showers across islands over the period August 12 through 15. At the airport, 16 mm or 0.63 inches was measured from the tropical wave that eventually developed into Tropical Storm Fay. Hanna Hanna became the eighth named storm of the season and like Fay, it did not become a hurricane. The system formed about 300 miles northeast of Antigua and Barbuda on August 28 (See Map 1). Shortly thereafter, the storm passed north of the islands as a minimal tropical storm. Over the period August 27 through 31, moisture from Hanna caused frequent periods of scattered to numerous showers across Antigua and Barbuda. Some of these showers were locally heavy with 62.1 mm or 2.44 inches falling at the airport over the period August 28 to 31. 2

4 ame THE ATLA TIC HURRICA E SEASO SUMMARY Date Max Wind (mph) Deaths Antigua/Barbuda Damage - US$Million 1. TS ARTHUR May 31 Jun MH BERTHA Jul TS CRISTOBAL Jul H DOLLY Jul TS EDOUARD Aug TS FAY Aug MH GUSTAV Aug 25 Sep H HANNA Aug 28 Sep MH IKE Sep TS JOSEPHINE Sep H KYLE Sep TS LAURA Sep 29 Oct TS MARCO Oct TS NANA Oct MH OMAR Oct * 16. TD SIXTEEN Oct MH PALOMA Nov Table 1: The Atlantic Hurricane Season Summary *Approximately. Totals: 17 Depressions, 16 Named Storms, 8 Hurricanes & 5 Major Hurricanes. The season caused about 933 deaths and over 43 billion US dollars in damage. (Sources NOAA and Wikipedia.com) 3

5 Map: 1 Storm Tracks 2008 (Picture Courtesy NOAA) Dale Destin 4