The Season Summary – 2009 Special Focus on Antigua and Barbuda

Dale C. S. Destin Antigua and Barbuda Meteorological Service #ovember 30, 2009

The Season in Brief

The 2009 Atlantic Hurricane Season produced nine (9) named storms. Of the nine (9) storms, three (3) became hurricanes and two (2) strengthened to achieve major hurricane status (category three (3) or higher on the Saffir-Simpson Hurricane Wind Scale). The strongest for the season was Hurricane Bill with peak winds of 135 mph, category 4. Relative to Antigua and Barbuda, the rest of the and the British Virgin Islands, five (5) tropical cyclones entered the monitored area (5 and 22N, 40 and 70W). These were Ana, Bill, Erika, Grace and Henri. No hurricane affected Antigua and Barbuda this year. However, the islands were affected by Tropical Depression Ana and Tropical Storm Erika i.e. these systems passed within 120 statute miles of Antigua and Barbuda. The last hurricane to affect Antigua and Barbuda was Omar of October 2008.

This season tied 1997, 1994, 1987, 1983, 1972, 1962, 1957 and 1946 for the second lowest number of hurricanes, for a season, for the period 1944 – 2009. It was a near normal season with respect to named storms and major hurricanes. However, regarding hurricanes, the season was below normal. The season also produced the lowest number of named storms since 1997. In terms of the Accumulated Cyclone Energy (ACE) index, which measures the collective strength and duration of named storms and hurricanes, the season was below normal. It had an index of 50.8, 55% of the median (93) or 50% of average (102); the lowest since 1997. Only 15 other years have recorded lower ACE indices for the period 1944 - 2009. Overall, tropical cyclone activity caused over 2.253 million US dollars in damage. For Antigua and Barbuda, the cost from cyclones was minor. See table 1 and map 1 for all of the 2009 Atlantic Tropical Cyclones.

The below and near normal numbers for the hurricane season were due mainly to a developing El Nino, over the Pacific Ocean during the summer. El Nino produced strong across the Atlantic Basin, which resulted in fewer and shorter lived storms compared to recent very active years. Most of the forecasts for the season were within acceptable range with regards to the number of named storms and major hurricanes. However, most of the same forecasts showed significant errors in the number of hurricanes that were forecast (see table 3). An average season has 11 named storms and six (6) hurricanes, including 3 major hurricanes (1950 – 2008).

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Tropical Cyclone in the Monitored Area

Tropical Storm Ana (August 11 – 16, 2009)

Ana affected Antigua and Barbuda on August 16 and 17 with storm force gusts experienced early on August 17. The tropical depression which eventually became tropical storm Ana was formed on August 11. After formation, the depression briefly strengthened to a Tropical Storm (Ana) on August 12. However, on August 13, exposure to upper level wind shear and dry air led to the storm degenerating into a remnant low. After a day or so of very little convection, by 0000 UTC, August 15, the remnants of Ana, in a less hostile environment, regenerated into a tropical depression and then back to tropical storm status by 0600 UTC, August 15. Information, alert and watch statements were issued for the Leeward Islands and British Virgin Islands August 13 to 17 (see table 2). Oddly, according to the NHC best track report on Ana, the system dissipated near 14.6N and 54.8W between 1200 and 1800 UTC, on August 16. However, what was experienced in Antigua on the night of the August 16/August 17 suggested that the system may have instead reached the islands as a tropical depression before dissipating. At the V. C. Bird International Airport the maximum 1-minute sustained wind speed measured was 32 knots; the maximum 10-minute speed was 29 knots, and the maximum gust was 39 knots. These wind speeds were measured over the period 0420 – 0430 UTC, 17 August. Showers and thunderstorms associated with the system occurred across Antigua and Barbuda on the night of August 16 through the morning of August 17. Some showers were locally heavy and resulted in minor flooding in prone and low-lying areas. At the V. C. Bird International Airport, 7.9 mm were measured over the period 2100 UTC, August 16 to 1200 UTC, August 17. There were only minor damages.

Major Hurricane Bill (August 15 – 24, 2009)

Hurricane Bill passed a safe distance of about 296 statute miles north of the Leeward Islands and the British Virgin Islands on August 20. It was formed out of a vigorous on August 15. It reached tropical storm status on the day it was formed, hurricane status on August 17 and major hurricane on August 19. Information, pre-alert and alert statements were issued for the Leeward and British Virgin Islands August 16 through 24 (see table 2). The system’s impact on the Leeward Islands and the British Virgin Islands was minimal. August 19 through 21, the system caused periods of showers and elevated seas to affect Antigua and Barbuda. Some showers were isolatedly heavy; there were also thunderstorms, at least on August 19. At the V. C. Bird International Airport, 6.3 mm were measured from the system over the period August 19 to 21. There were fairly minor damages mainly to coastal areas from swells.

Tropical Storm Erika (September 1 – 4, 2009)

Erika affected Antigua and Barbuda on September 2 and 3 with storm force gusts experienced early on September 3. The disturbance that eventually became tropical storm Erika on September 1, skipped the depression stage. After formation, the storm struggled under strong vertical wind shear. This shear resulted in the system being very disorganized and its centre extremely difficult to locate. Initially forecast to pass north of the islands, it eventually passed over , 56 statute miles south of Antigua, on September 2. Alert, watch and warning statements were issued 2

for the Leeward Islands and alerts for the British Virgin Islands September 1 to 4 (see table 2). At the V. C. Bird International Airport, the maximum 1-minute sustained wind speed measured was 30 knots; the maximum 10-minute speed was 29 knots, and the maximum gust was 38 knots. These wind speeds were measured over the period 0700 – 0710 UTC, September 3. Most of the associated showers occurred on September 3; thunderstorms took place on September 2 and 3. Some showers were isolatedly heavy and resulted in minor flooding in flood prone and low-lying areas. In total, 49.2 mm were measured from the system, at the airport, over the period September 1, 1200 UTC to September 4, 0000 UTC. There were only minor damages.

Tropical Storm Grace (October 4 – 5, 2009)

Tropical Storm Grace did not impact the in any way. The Storm formed in the Eastern Atlantic, just northeast of the Azores on October 4 and generally moved northeasterly. It eventually dissipated a few hundred miles west of the British Isles, but the remnants reached England.

Tropical Storm Henri (October 6 – 8, 2009)

While Henri did not strike or brush any of the islands, i.e. it did not come within 125 statute miles of the area, it dissipated close enough to result in some of the Leeward Islands and British Virgin Islands having some showers, thunderstorms and elevated seas on October 8 and 9. The storm formed from a low pressure area on October 6, without going through the depression stage. Alert statements were issued for the Leeward and British Virgin Islands October 6 through 8 (see table 2). The system’s impact on the Leeward Islands and the British Virgin Islands was minimal. On October 8 and 9, Henri caused some periods of showers and elevated seas, due to its proximity to the area. Some showers were isolatedly heavy, and there were also thunderstorms on October 9. At the V. C. Bird International Airport, 7.1 mm were measured from the system over the period October 8, 2300 UTC and October 9, 1200 UTC. There were fairly minor damages mainly to coastal areas from swells.

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THE ATLA#TIC HURRICA#E SEASO# SUMMARY - 2009 Max Wind Antigua/Barbuda #ame Date Deaths (mph) Damage - US$Million 1. TD ONE May 28 - 29 35 0 0

2. TS ANA Aug 11 – 16 40 0 Minimal

3. MH BILL Aug 15 – 24 135 2 Unknown

4. TS CLAUDETTE Aug 16 – 18 50 2 0.103

5. TS DANNY Aug 26 – 29 60 1 None

6. TS ERIKA Sep 1 - 4 60 0 Minimal

7. MH FRED Sep 7 – 12 120 0 -

8. TD EIGHT Sep 25 – 26 35 0 None

9. TS GRACE Oct 4 – 6 70 0 Unknown

10. TS HENRI Oct 6 – 8 50 0 0

11. H IDA Nov 4 - 10 105 10 2.5 Table 1: The Atlantic Hurricane Season Summary - 2009. Totals: 11 Tropical Cyclones, 9 Named Storms, 3 Hurricanes & 2 Major Hurricanes. The season caused about 5 deaths and over near 2.253 billion US dollars in damage. (Sources – NOAA and Wikipedia.com)

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STATEME#TS ISSUED BY THE ABMS DURI#G THE 2009 HURRICA#E SEASO#

Statements Issued for the Hurricane Season by the ABMS

#ame Information Pre-alert Alert Watch Warning

1. TD ONE 0 0 0 0 0

2. TS ANA 2 0 20 45 0

3. MH BILL 2 2 9 0 0

4. TS CLAUDETTE 1 0 0 0 0

5. TS DANNY 3 0 0 0 0

6. TS ERIKA 0 0 30 11 35

7. MH FRED 4 3 0 0 0

8. TD EIGHT 2 2 0 0 0

9. TS GRACE 2 0 0 0 0

10. TS HENRI 0 0 7 0 0

11. H IDA 8 0 0 0 0

Total 16 7 66 56 35 Table 2: Statements issued by the Antigua and Barbuda Meteorological Service (ABMS) during the 2009 Atlantic Hurricane Season.

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Tropical Forecast Source Forecast Date Storms Hurricanes Major Hurricanes August 6, 2009 7 – 11 3 – 6 1 – 2 NOAA May 21, 2009 9 – 14 4 – 7 1 – 3 June 2, 2009 11 5 2 CSU April 7, 2009 12 6 2 June 4, 2009 11 5 – 6 2 – 3 TSR April 7, 2008 15 7 – 8 3 – 4 MOHC (range) June 18, 2009 6 (3 – 9) - - 59 -yr Antigua 1 1950 - 2008 0.6 0.4 0.2 Climatology 59 -yr Atlantic Climatology 1950 - 2008 10.8 6.2 2.7 30 -yr Atlantic Climatology 1979 - 2008 11.8 6.4 2.6

Observed Cyclones 2009 9 3 2 Table 3: Comparison of 2009 Hurricane Season Forecasts. 1Storms passing within 105 nautical miles of Antigua. Forecasts include those issued by Colorado State University (CSU), Tropical Storm Risk (TSR), the National Oceanic and Atmospheric Administration (NOAA) and the Meteorological Office Hadley Centre (MOHC). The MOHC forecast is issued for the July– November period.

Map: 1 Storm Tracks – 2009 (Picture Courtesy NOAA).

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