THE ATLANTIC HURRICANE SEASON SUMMARY – 2012
SPECIAL FOCUS ON ANTIGUA AND BARBUDA
(PRELIM INARY)
Dale C. S. Destin Antigua and Barbuda Meteorological Service mail | twitter | facebook | youtube | blog November 30, 2012
Satellite Image: Tropical Storm Rafael – Oct 14, 02:15 UTC 2012
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The Atlantic Hurricane Season Summary – 2012 Special Focus on Antigua and Barbuda
Dale C. S. Destin Antigua and Barbuda Meteorological Service mail | twitter | facebook | youtube | blog November 30, 2012
The Season in Brief
The 2012 Atlantic Hurricane Season produced nineteen (19) named storms. Of the nineteen (19) storms, ten (10) became hurricanes and one (1) 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, in terms of pressure was Hurricane Sandy with peak winds of 110 mph and minimum pressure of 940 mb; however, category 3, Major Hurricane Michael had the highest sustained winds of 115 mph and minimum pressure of 964 mb.
Relative to Antigua and Barbuda
Relative to Antigua and Barbuda, the rest of the Leeward Islands and the British Virgin Islands, five (5) tropical cyclones entered or formed in our defined monitored area (10N 40W – 10N 55W – 15N 70W – 20N 70W – 20N 55W – 15N 40W – 10N 40W). These were Ernesto, Isaac, Joyce, Leslie and Rafael. Isaac and Rafael went on to brush Antigua and Barbuda; both were tropical storms at the time of affecting the area. As far as land-falling hurricanes are concerned, this year marks 13 straight years without a tropical cyclone producing sustained hurricane force winds across Antigua; the last tropical cyclone to do this was Jose in 1999. Nonetheless, wind is not the only threat from tropical cyclones; Rafael caused moderate flooding across low-lying and flood prone areas of Antigua.
Detail and Perspective
This season had well above the normal of 12 named storms, above the normal of 6 hurricanes and below the normal of three major hurricanes; the season tied with 2011, 2010, 1995 and 1887 for the third highest number of named storms since record began in 1851 and the second highest for the period 1981 – 2012. Further, the season was above normal with respect to the Accumulated Cyclone Energy (ACE) index, which was 129. The ACE index, measures the collective strength and duration of named storms and hurricanes. The index was 139% of the median and 122% of average (1981 – 2010); this is the 32nd highest index since record began and 11th highest for the period 1981 – 2012. This ranking is fairly low considering the number of storms. This relatively low ACE ranking was clearly as a result of a relatively high number of short-lived and weak storms. Many seasons in the historical record have had a much lower total tropical storm count, yet much higher ACE Index. Overall, tropical cyclone activity caused over 68 billion US dollars in damage and 327 deaths. For Antigua and Barbuda, Isaac and Rafael
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caused minor damage, mainly as a result of rough seas and heavy rainfall. See table 1 and map 1 for all of the 2012 Atlantic Tropical Cyclones.
A number of records were or nearly broken this hurricane season. The first tropical cyclone for the season was Tropical Storm Alberto, which developed on May 19; while the last storm was Tropical Storm Tony, dissipated on October 25. The season had a hectic start and by June 23 Debby formed and become the earliest 4th named storm on record. Prior to the official start of the hurricane season, June 1, there were two preseason storms – Alberto and Chris – the second time on record two storms form in May in a given year, May 1887 was the only other time. It was also the first time since 1908 two named storms proceeded the hurricane season and the third time on record. The most intense hurricane, in terms of lowest central pressure, was Hurricane Sandy; it is also considered the largest known Atlantic hurricane by gale diameter on record. Hurricane Nadine was the fifth longest-lived tropical cyclone on record. In addition, August 2012 was tied with August 2004, September 2002, and September 2010 for most number of named storms in a particular month, at eight. However, despite the high number of hurricanes during the 2012 season, only one, Hurricane Michael, attained major hurricane intensity—a Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale.
The well above normal season was caused mainly by above normal sea surface temperatures in the Atlantic Ocean, especially in the Tropical North Atlantic. Most of the forecasts for the season, especially those before August, did an ordinary to poor job (see table 2), mainly as a result of a forecast El Nino, which would have likely suppress activity, but it did not materialize. An average season has 12 named storms and six (6) hurricanes, including 3 major hurricanes (1981 – 2010).
Tropical Cyclone in the Monitored Area
The zone described by 10N 40W – 10N 55W – 15N 70W – 20N 70W – 20N 55W – 15N 40W – 10N 40W is defined as our monitored area with respected to tropical cyclones. About 80% of all cyclones to affect Antigua have formed in this area.
Hurricane Ernesto (Aug 1 - 10, 2012)
Ernesto did not affect Antigua and Barbuda. At its closest point, the centre of the storm passed about 215 miles south of Antigua on the morning of August 3. The system did not cause any strong wind or rainfall across the area.
Ernesto developed from a tropical wave into Tropical Depression Five late on August 1. Late on August 2, Tropical Storm Ernesto formed. The next day, the storm moved over or very near St. Lucia. By August 3, Ernesto entered the Caribbean Sea, with anticipation of further strengthening as a hurricane by the next several days. Ernesto regained deep convection and became a hurricane on August 6; it eventually dissipated over Mexico. Ernesto made landfall on St. Lucia and affected Barbados, St. Vincent and nearby Windward Islands; it also made landfall on Mexico.
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Hurricane Isaac (Aug 21 – Sep 1, 2012)
Isaac brushed Antigua and Barbuda as a storm on August 22 and 23. At its closest point, the centre of the storm passed about 76 miles south of Antigua between 5 and 8 pm on August 22. At the V. C. Bird International Airport in Antigua, the maximum 1-minute sustained wind from the storm was 35 mph with a maximum gust of 44 mph. There were no sustained storm force winds recorded; however, this may have occurred in some areas on the southern side of Antigua. Total rainfall from the system, measured at the airport, was 27.3 mm or 1.07 inches over the period August 20 to August 23. The system also affected Montserrat, Nevis and St. Kitts.
Isaac developed from a tropical wave into Tropical Depression Nine on August 21. The depression intensified into Tropical Storm Isaac six hours later. At 1620 UTC on August 28, Isaac was upgraded to a Category 1 hurricane. Isaac made landfall on Haiti, Cuba and Louisiana. It eventually transitioned into an extratropical cyclone over Missouri on September 1.
Tropical Storm Joyce (Aug 22 – 24, 2012)
Joyce did not affect Antigua and Barbuda. The storm barely entered the monitored area and dissipated about 300 miles east of Barbuda on the morning of August 24.
Joyce developed from a tropical wave to Tropical Depression Ten, nearly 900 miles WSW of Cape Verde and on August 23 strengthened into Tropical Storm Joyce. However, strong wind shear to the south of the centre of circulation inhibited further development; with most of the convectional for the system remaining displaced to the north, Joyce soon weakened and dissipated during the morning of August 24.
Hurricane Leslie (Aug 30 – Sep 11, 2012)
Leslie did not affect Antigua and Barbuda. At its closest point, the centre of the storm passed about 295 miles south of Antigua on the morning of September 2. The system did not cause any strong wind across the area and rainfall totals were less than 1 mm.
Leslie developed from a tropical wave into Tropical Depression Twelve about 1,185 miles east of the Windward Islands. Favourable conditions resulted in quick intensification of Leslie into a tropical storm on August 30. Leslie was upgraded to a hurricane on September 5. On September 11, Leslie made landfall over Marystown, Newfoundland and Labrador, Canada with winds of 70 mph as it became extratropical (lost tropical characteristics).
Hurricane Rafael (Oct 12 – 17, 2012)
Rafael brushed Antigua and Barbuda on October 13 – 14 as a tropical storm; it also affected the rest of the Leeward Islands and the Virgin Islands. At its closest point, the centre of the storm passed about 95 miles west of the islands (Antigua and Barbuda). At the V. C. Bird International Airport in Antigua, the maximum 1-minute sustained winds measured was 29 mph and the maximum gust was 39 mph; the total rainfall measured was 146.5 mm or 5.77 inches for the
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period October 12 to 17. There was moderate flooding as a result of heavy rainfall from Rafael; some areas had much higher totals than measured at the Airport.
Rafael developed from a tropical wave into a tropical storm on October 12 about 125 miles west- southwest of Dominica. On October 15, Rafael strengthened into a hurricane as it turned northward. On October 17, the storm lost its tropical characteristics, but remained strong. The remnants continued to be monitored and the extratropical system soon began to show signs of a subtropical storm, but quickly moved inland over Europe before further strengthening could occur.
THE ATLANTIC HURRICANE SEASON SUMMARY - 2012 Max Wind Antigua/Barbuda Name Date Deaths (mph) Damage - US$Million 1. TS ABERTO May 19 – May 22 60 0 0 2. TS BERYL May 26 – 30 70 0
3. H CHRIS Jun 19 – 22 75 0
4. TS DEBBY Jun 23 – 27 60 0
5. H ERNESTO Aug 1 – 10 85 Minimal
6. TS FLORENCE Aug 3 – 6 60 0
7. H GORDON Aug 15 – 20 110 0
8. TS HELENE Aug 9 – 18 45 0
9. H ISAAC Aug 21 – Sep 1 80 Minimal
10. TS JOYCE Aug 22 – 24 40 0
11. H KIRK Aug 28 – Sep 2 105 0
12. H LESLIE Aug 30 – Sep 11 75 Minimal
13. MH MICHAEL Sep 3 – 11 115 0
14. H NADINE Sep 11 – Oct 4 90 0
15. TS OSCAR Oct 3 – 5 50 0
16. TS PATTY Oct 11 – 13 45 0
17. H RAFAEL Oct 12 – 17 90 Unknown
18. H SANDY Oct 22 – 29 110 0
19. TS TONY Oct 22 – 25 50 0
Table 1: The Atlantic Hurricane Season Summary - 2012. Totals: 19 Named Storms, 10 Hurricanes and 1 Major Hurricanes. The season caused about 327 deaths and over 68 billion US dollars in damage. (Sources – NOAA, Wikipedia.com and ABMS). 5
Map: 1 Storm Tracks – 2012 (Picture Courtesy NOAA).
References
National Hurricane Centre, Maimi, Monthly Atlantic Weather Summary [online]. Available from:
National Oceanic and Atmospheric Administration, Silver Spring, Busy 2012 Hurricane Season Continues Decade-Long High Activity Era in the Atlantic [online].
Wikipedia [online] Available from:
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