THE ATLANTIC HURRICANE SEASON SUMMARY – 2010 SPECIAL FOCUS ON ANTIGUA AND BARBUDA Radar Image: Hurricane Earl 2315 UTC, August 29, 2010 Barbuda Antigua Courtesy Meteo France Dale C. S. Destin Antigua and Barbuda Meteorological Service May 31, 2011 1 The Atlantic Hurricane Season Summary – 2010 Special Focus on Antigua and Barbuda Dale C. S. Destin Antigua and Barbuda Meteorological Service May 31, 2011 The Season in Brief The 2010 Atlantic Hurricane Season produced nine (19) named storms. Of the nineteen (19) storms, twelve (12) became hurricanes and five (5) strengthened to achieve major hurricane status (category three (3) or higher on the Saffir-Simpson Hurricane Wind Scale). The strongest tropical cyclone for the season was Hurricane Igor with peak winds of 155 mph, category 4. Relative to Antigua and Barbuda, the rest of the Leeward Islands and the British Virgin Islands, six (6) tropical cyclones entered the defined monitored area (10N 40W – 10N 55W – 15N 70W – 20N 70W – 20N 55W – 15N 40W – 10N 40W). These were Collin, Danielle, Earl, Fiona, Igor, and Tomas. By the national definition, Hurricane Earl hit Antigua and Barbuda and Fiona hit Barbuda and brushed Antigua. This season was well above normal (extremely active) with respect to named storms and hurricanes, and above normal with respect to major hurricanes and Accumulated Cyclone Energy (ACE) index. This season tied with the 1969 seasons for the second most hurricanes and with the 1995 and 1887 seasons for the third most named storms. Also, this was the most active season since 2005. In terms of the ACE index, which measures the collective strength and duration of named storms and hurricanes, the season was solidly above normal. It had an index of 166, 183% of the median (90.5) or 164% of average (101.2); the 11th highest on record (1944 – 2010) and the highest by far since 2005. Overall, tropical cyclone activity caused about 11.2 billion US dollars in damage. For Antigua and Barbuda, Hurricane Earl cost little over US$12.5 million dollars in damage and loss of revenue. See table 1 and map 1 for all of the 2010 Atlantic Tropical Cyclones. The season started out quite slowly contrary to the forecasts. It was such a slow start that Phillip Klutzbach, who is the lead forecaster of the CSU Forecast of the Atlantic Hurricane Season, admitted, in conversation with me at the VII International Workshop on Tropical Cyclone, that he became a bit nervous when after the middle of August there were only three (3) named storms. However, one could say “all hell broke loose” on August 21 with the formation of Danielle, which was followed by 10 other named storms in the following 38 days. Of the 11 named storms, there was a record number of eight (8) that formed in September, tying with the 2002 and 2007 season. Additionally, Igor and Julia were simultaneously category 4 hurricanes, a very rare occurrence which has not happened since 1926. The well above normal season was due mainly to record high sea surface temperatures in the Atlantic Ocean, especially in the Tropical North Atlantic and the development of La Nina in the Pacific Ocean. All the forecasts for the season, which came out after March were excellent in 2 projecting the number of named storms and major hurricanes. With respect to the number of hurricanes, the forecasts had mixed success (see table 2). An average season has 11 named storms and six (6) hurricanes, including 3 major hurricanes (1950 – 2009). Tropical Cyclone in the Monitored Area Tropical Storm Colin (August 2 - 8, 2010) Tropical Storm Colin did not strike or hit any of the islands, i.e. it did not come within 125 statute miles of the area. It dissipated several hundred miles east of Antigua and Barbuda. However, as an open trough it produced rainfall across the islands; 7.9 mm or 0.31 inch was measured at the airport. Tropical Storm Colin formed on August 2, starting out as a tropical depression, which then became a storm on August 3. This intensification of Colin was short-lived as hostile environmental conditions along with a very rapid forward speed caused degeneration into an open trough by 2 P. M. on August 3. The system eventually regenerated to a storm on August 5, over 400 miles northwest of Antigua and Barbuda. Colin eventually dissipated about 60 mi northwest of Bermuda on August 8. Tropical Hurricane Danielle (August 21 - 30, 2010) Hurricane Danielle passed a safe distance of over 600 miles northeast of Antigua and Barbuda and the rest of Leeward Islands and the British Virgin Islands on August 3. Notwithstanding the distance, a trough associated with the hurricane produced rainfall across the islands with 10.2 mm or 0.40 inch measured at the airport. Danielle formed out of an area of low pressure which moved off the west coast of Africa on August 19. Moving through favorable conditions, it developed into Tropical Depression Six near the Cape Verde Islands on August 21. The system attained tropical storm status on August 22. The next day it attained hurricane status, becoming the second of the season. Over the next few days, the system’s strength varied between storm and category 2 hurricane. On August 27, Danielle strengthened to a Category 3 hurricane, becoming the first major hurricane of the season, and further strengthened to a Category 4 hurricane shortly after. The hurricane did not make landfall anywhere. Danielle eventually lost its tropical characteristics and became extratropical late on August 30 southeast of Newfoundland without having directly impacted land. It was fully absorbed by a larger extratropical low on September 3 south of Iceland. Major Hurricane Earl (August 25 – September 4, 2010) Earl affected Antigua and Barbuda on August 29 and 30 with storm force winds of 52 mph gusting 64 mph experienced at the airport on August 30. At its closest point, the centre of the hurricane was about 28 miles north of Barbuda at about 2 am August 30 and about 55 miles north-northeast of Antigua at about midnight August 29. The system produced all together 198.3 mm or 7.81 inches of rainfall at the V. C. Bird International Airport. Some of this rainfall 3 resulted in moderate flooding. The system also affected the rest of the Leeward Islands and the British Virgin Islands. Earl developed from an area of disturbed weather, which came off the African west coast on August 22. The system became a depression on August 25. Later on August 25, it was upgraded to a tropical storm and a hurricane on August 29, the third for the season. The upgrade to a hurricane took place about 211 miles east of Antigua. Earl then strengthened further to a category 2 hurricane near Antigua and Barbuda, category 3 hurricane near Anguilla and a category 4 hurricane just after passing the British Virgin Islands. Earl was the second major hurricane for the season. After passing the Northeast Caribbean, the system tracked toward the northwest then turning north passing within 100 miles of Cape Hatteras, North Carolina on September 2 as a category 2 hurricane. It then skirted the rest of the US east coast north of Cape Hatteras until it made landfall in Nova Scotia Canada on September 4, as a strong storm. The system became extratropical on September 5. It was estimated that throughout the Caribbean, Hurricane Earl wrought up to US$150 million in damage. Two deaths were directly attributable to the storm, one in Nova Scotia, one in the Leeward Islands. Tropical Storm Fiona (August 30 – September 3, 2010) Fiona affected Antigua and Barbuda, on September 1. At, its closest point, the centre of the storm was 65 miles northeast of Barbuda and 80 miles northeast of Antigua on the morning of September 1. Hence, by national definition, the system hit Barbuda and brushed Antigua; although, minimal storm force winds were likely experienced across Barbuda, it is not possible to say for sure since there were no working instruments on the island. For Antigua, only 15 mph winds were measured at the airport in Antigua; the maximum gust was 21 mph. Instability associated with the system produced 6.5 mm at the airport. Fiona came closely on the heels of Hurricane Earl. Just as the country was saying good riddance to Hurricane Earl, Fiona was there. Interestingly, this system came off the coast of Africa during the same week as Earl. It struggled to develop until August 30, when it became better organized a few hundred miles east of the Lesser Antilles and became Tropical Storm Fiona; the depression stage was missed. Having developed, it struggled in the high wind shear from the outflow of the much larger and stronger Earl. Notwithstanding this, the system got to a maximum strength of 65 mph, then weakening slowly into an open wave just south of Bermuda on September 4. Hurricane Igor (EEgor) (September 8 – 21, 2010) Igor entered the monitored area; however, it passed a safe distance away from the islands, about 390 miles northeast of Antigua. Igor formed from a large and strong area of low pressure area associated with a broad tropical disturbance, which came off Western Africa on September 6. It then became a tropical depression and a tropical storm on September 8, the ninth of the season. After struggling through significant shear to the point of weakening to a depression on September 9, it regained tropical storm status on September 10. The system strengthened to a hurricane on September 11. Rapid strengthening took place on September 12 and the Igor became a category 4 hurricane.