1 Tropical Cyclone Report Hurricane Maria
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Tropical Cyclone Report Hurricane Maria (AL142011) 6-16 September 2011 Michael J. Brennan National Hurricane Center 11 January 2012 Maria formed in the eastern Atlantic Ocean and brought tropical storm conditions to portions of the Lesser Antilles. Maria then became a category 1 hurricane (on the Saffir- Simpson Hurricane Wind Scale) as it recurved through the northwestern Atlantic before it made landfall in Newfoundland as a strong tropical storm. a. Synoptic History Maria originated from a tropical wave that moved across the west coast of Africa on 2 September. The wave moved westward well to the south of the Cape Verde islands on 3-4 September with little in the way of organized deep convection. Thunderstorm activity increased markedly early on 5 September but remained displaced to the west of the broad surface circulation due to strong easterly vertical wind shear. On 6 September, the low-level center became better defined and deep convection increased further and a tropical depression formed by 1800 UTC that day, centered about 700 n mi west-southwest of the southern Cape Verde Islands. The cyclone moved quickly west-northwestward at 15 to 20 kt and reached tropical storm intensity 6 h later, while centered about 790 n mi west-southwest of the southern Cape Verde Islands. The “best track” chart of Maria’s path is given in Fig. 1, with the wind and pressure histories shown in Figs. 2 and 3, respectively. The best track positions and intensities are listed in Table 11. Maria moved quickly west-northwestward to the south of a subtropical ridge on 7 September and reached an intensity of 45 kt around 1200 UTC that day. However, by early the next day southwesterly vertical wind shear increased over the cyclone, and the deep convection became displaced to the northeast of the fast-moving low-level center. By early on 9 September, the forward speed of Maria slowed to around 15 kt as the storm turned west-northwestward, and deep convection began to redevelop closer to the low-level circulation. However, data from an Air Force Reserve Hurricane Hunter aircraft mission into Maria later that day indicated that the low-level circulation lost definition, even as the system was producing maximum sustained winds of around 45 kt mainly to the northeast of the center. Based on the aircraft data, satellite imagery, and surface observations, it is estimated that Maria no longer had a well-defined center and dissipated as a tropical cyclone around 1200 UTC 9 September. 1 A digital record of the complete best track, including wind radii, can be found on line at ftp://ftp.nhc.noaa.gov/atcf. Data for the current year’s storms are located in the btk directory, while previous years’ data are located in the archive directory. 1 The remnants of Maria, accompanied by a strong mid-level circulation, turned northwestward and approached the Lesser Antilles by late on 9 September. Satellite imagery and surface and aircraft observations indicate that a new center developed around 1200 UTC 10 September about 40 n mi east-southeast of Antigua, and Maria again became a tropical storm at that time. Maria continued to experience strong westerly vertical wind shear while it moved northwestward and then west-northwestward, and its forward motion slowed as the center passed to the north of the Virgin Islands and Puerto Rico the next day. The forward speed of Maria slowed considerably on 12 September when the cyclone reached the southwestern periphery of the subtropical ridge. Maria then turned northwestward while its forward speed increased to around 10 kt by 0000 UTC 14 September. Vertical wind shear relaxed somewhat during the next day or so and Maria began to be steered by a deep-layer trough moving off of the east coast of North America. The cyclone slowly strengthened on 14 September as deep convection became more concentrated near the center. Maria turned northward by 15 September and continued strengthening, reaching hurricane intensity around 1800 UTC that day while centered about 135 n mi northwest of Bermuda (Fig. 4). On 16 September, Maria became embedded in the mid-latitude flow and accelerated northeastward, reaching an estimated peak intensity of 70 kt at 0000 UTC that day, before weakening due to cooler waters and increased vertical wind shear. Maria was a 60-kt tropical storm when the center made landfall around 1830 UTC 16 September near Cape St. Mary’s on the Avalon Peninsula of Newfoundland, Canada. The cyclone’s circulation was absorbed by a frontal system shortly thereafter. b. Meteorological Statistics Observations in Maria (Figs. 2 and 3) include subjective satellite-based Dvorak technique intensity estimates from the Tropical Analysis and Forecast Branch (TAFB) and the Satellite Analysis Branch (SAB), and objective Advanced Dvorak Technique (ADT) estimates from the Cooperative Institute for Meteorological Satellite Studies/University of Wisconsin-Madison. Observations also include flight-level, stepped frequency microwave radiometer (SFMR), and dropwindsonde observations from six flights of the 53rd Weather Reconnaissance Squadron of the U.S. Air Force Reserve Command. Data and imagery from NOAA polar-orbiting satellites, including the Advanced Microwave Sounding Unit, the NASA Tropical Rainfall Measuring Mission (TRMM) and Aqua, the European Space Agency’s Advanced Scatterometer (ASCAT), and Defense Meteorological Satellite Program (DMSP) satellites, among others, were also useful in constructing the best track of Maria. Ship and fixed platform reports of winds of tropical storm force associated with Maria are given in Table 2, and selected surface observations from land stations and data buoys are given in Table 3. As Maria and its remnants passed near and north of the Leeward Islands and the Virgin Islands on 9-11 September, the strongest observed sustained wind was 45 kt at La Desirade, located just to the east of Guadeloupe. Tropical-storm-force wind gusts were observed on Antigua, Guadeloupe, Marie-Galante, Barbuda, St. Maarten/St. Martin, St. Croix, and St. 2 Thomas, but sustained winds remained below tropical storm force. In several of these locations, the strongest winds occurred before Maria regenerated into a tropical cyclone. Widespread rainfall totals of 5 to 11 inches were observed in Puerto Rico (Fig. 5), with a maximum of 11.60 inches at Aibonito. Rainfall totals in the Leeward Islands were generally 1 to 2 inches. Maria produced storm surge values of 0.50 to 0.75 ft in Barbuda, St. Croix, St. John, Vieques, Mona Island, and Puerto Rico. The highest observed storm tide was 2.03 ft above Mean Lower Low Water at Arecibo on the northern coast of Puerto Rico. As Maria passed west of Bermuda on 15 September, sustained winds of 34 kt were reported at L.F. Wade International airport, along with a peak wind gust of 43 kt. Maria’s analyzed peak intensity of 70 kt is based on a blend of subjective Dvorak intensity estimates of 77 kt from TAFB and 65 kt from SAB and a 3-h average ADT intensity estimate of 72 kt from UW-CIMSS at 0600 UTC 16 September. The estimated minimum central pressure of 983 mb is based on an observed pressure of 985.4 mb with 25-kt winds at Environment Canada buoy 44141 around 1200 UTC 16 September. Maria made landfall in Newfoundland around 1830 UTC 16 September on the Avalon Peninsula near Cape St. Mary’s as a strong tropical storm with maximum sustained wind of 60 kt. The estimated landfall intensity is based on subjective Dvorak intensity estimates of 55 kt from TAFB and SAB at 1800 UTC and a 10-min wind of 52 kt from Environment Canada buoy 44138 at 1520 UTC, which suggests a peak 1-min wind of 57 kt when applying an adjustment factor of 1.11 (Harper et al. 2009). The analyzed minimum central pressure of 983 mb at landfall is based on an observed pressure at Grate’s Cove of 983.9 mb, which occurred with 16 kt of wind. The strongest winds associated with Maria remained offshore to the southeast of Newfoundland, though sustained tropical-storm-force winds were observed at Cape Race, Bonavista, and Sagona Island, with wind gusts above 50 kt observed at all of those locations as well as at St. Lawrence. Rainfall amounts in the Burin Peninsula and the south coast of Newfoundland were around 2.35 inches (60 mm), with a total of 2.48 inches (63 mm) observed at St. Lawrence. c. Casualty and Damage Statistics There were no reports of casualties associated with Maria. In Puerto Rico numerous roads were flooded due to rainfall and 20 homes were flooded in Cabo Rojo. Thirty families were moved to shelters after their homes were flooded in Ceiba, Juana Diaz, and Barranquitas. A total of 15,700 people lost power in Puerto Rico due to the storm. No monetary damage estimates are available. No other reports of damage or impacts were received. 3 d. Forecast and Warning Critique The genesis of Maria was not well anticipated. The precursor system that developed into Maria was not introduced into the Tropical Weather Outlook until 30 h before genesis, when it was given a low (< 30%) chance of development. However, the genesis probability was raised to the high category (> 50% chance of development) 6 h later and remained in that category until genesis occurred. A verification of NHC official track forecasts for Maria is given in Table 4a. Official forecast track errors (OFCL) were generally 20% to 25% larger than the mean official errors for the previous 5-yr period, except at 72 h when the average error was only about 10% above the mean 5-yr value.