Ana (tropical storm, 2009)

On August 9, 2009, the US National Hurricane Forecasting Center recorded a tropical airwave and associated convection of air masses between the Cape Verde archipelago and the west coast of Africa ^[1] . The resulting low-pressure region headed westward, slowly moving for several days towards the Caribbean Sea, intensifying on the night of August 11 until the second tropical depression in the 2009 Atlantic hurricane season ^[3] . By the morning of August 11, the cyclone was located at a distance of 455 kilometers west of Cape Verde, representing a deep depression with a developed system of convective flows around its own center of rotation ^[4] . During the day, there was a slight increase in atmospheric formation associated with the passage of the area of ​​warm sea currents with low wind shear ^[5] .

On August 12, the US National Hurricane Forecasting Center (NHC) announced that tropical depression level 2 was approaching tropical storm rates ^[6] . The NHC forecast was based on the appearance of a strong wave of convective flow around the center of rotation of the cyclone. A few hours later, the depression entered the phase of a tropical storm with an indicator of a steady wind speed at an intensity peak of 65 km / h (atmospheric pressure in the center of the cyclone was 753 millimeters of mercury ) ^[1] . After 12 hours, the storm weakened to tropical depression due to the occurrence of wind shifts in atmospheric formation, and by the end of the day it regained strength of the tropical storm ^[7] . At the same time, the level of deep convection of air flows decreased, completely eliminating the thunderstorm activity of the cyclone. In the afternoon of August 13, tropical depression degenerated into a low-pressure area without convective formations and the National Center for Hurricane Prediction for the next 24 hours recorded minimal cyclonic activity ^[8] . At the same time, the NHC issued a final cyclone summary with a note on the possible restoration of atmospheric activity in the area of ​​the disbanded storm ^[9] .

On August 14, at the beginning of the day, the re-formation of the area of ​​convection of air flows began. On the same day, meteorological probes were launched by a special unit of Hurricane Hunters to the cyclone area, according to which the US National Hurricane Forecasting Center concluded that the cyclone was in the process of regeneration and soon after that transferred to the category of tropical depression. The center of the cyclone was at that time 1735 kilometers east of the Lesser Antilles ^[10] , the cyclone itself continued to move westward, bypassing the area of ​​operation of the permanent Azores anticyclone in the North Antlantic ^[11] . In the early morning hours of August 15, the US National Hurricane Forecasting Center raised the status of the cyclone to the first tropical storm of the season, Ana from the list of reserved storm names for the Atlantic hurricane season of 2009 ^{[12] [13]} .

On August 16, the speed of the storm began to increase and at that moment the storm quickly moved into the area of ​​dry, stable air masses ^[14] . As the subsequent analysis of events showed, in the new environment, the element lost all its strength to the extent of an ordinary tropical wave, thereby ceasing to be a tropical cyclone ^[1] . By the end of the day, weather balloons transmitted information about the absence of storm winds in the cyclone, based on which the National Hurricane Prediction Center lowered Ana's status to tropical depression ^[15] . A few hours later, new emerging directions of deep convection were recorded in the region of passage of the cyclone; the wind speed reached 42 km / h with a direction to the west-north-west ^[16] . Nevertheless, this atmospheric activity was generated by the next tropical wave and had no connection with the previous tropical depression Ana ^[1] . In the early morning hours of August 17, Ana’s radar surveys in the Guadeloupe and San Juan areas of Puerto Rico showed that the depression was in full swing towards its disbandment. Despite this, the NHC continued to issue storm warnings until the confirmation of radar data by satellite images obtained in the visible range ^[17] . On the same day, another Hurricane Hunters aircraft examined the atmospheric activity of depression and also confirmed data from radar orbital stations. Shortly thereafter, the US National Hurricane Forecasting Center observed the disbandment of the tropical depression in the area of ​​the southern coast of Puerto Rico ^[1] . The remains of the cyclone continued to move west-north-west, but the meteorological situation did not allow it to recover to the level of a tropical storm. Soon, the last remains of the cyclone were scattered on the coast of Cuba ^[18] .

On the afternoon of August 15, the government of the Netherlands Antilles announced a storm warning for the Sint Maarten region and the Saba and Sint Eustatius islands ^[19] . A few hours later, a number of countries announced similar warnings for areas within the Lesser Antilles: Antigua , Barbuda , the British Virgin Islands , Montserrat , Saint Kitts and Nevis and Anguilla ^[20] . Early in the morning of August 16, a storm warning was issued in Puerto Rico ^[21] , and a couple of hours later on Dominica ^[22] . Before dinner on August 17, warnings of an impending storm were announced for the areas of Guadeloupe , the island of Saint Martin , Saint Barthelemy ^[23] , the eastern region of the Dominican Republic between and ^] . Soon after the Ana storm weakened to a tropical depression, the storm warning was canceled in Dominica ^[25] , and in the early hours of the following day in Antigua and Barbuda ^[26] . At the beginning of the afternoon, tropical depression entered the Caribbean Sea and the level of danger was extended to the entire northern coast of the Dominican Republic ^[27] . A few hours later, the depression disbanded to an area of ​​low pressure, so storm warnings were canceled in all countries ^{[28] [29]} .

To prevent the catastrophic consequences, Sint Maarten travel agencies redirected chartered cruise liners to other areas, several vessels went to the Simpson Bay lagoon, where sea waves, as a rule, do not reach storm sizes ^[30] . Of the potentially most vulnerable sections of the coastal province of in the south of the country, 40 families were evacuated by local administration ^[31] . In the Dominican Republic, authorities took measures to create rescue teams and organized several shelters from the elements. On August 17, the US National Meteorological Service in San Juan issued a warning about the possibility of minor floods and floods in all municipalities in the eastern part of the island ^[32] . All flights to Puerto Rico were delayed until the storm ^[33] . In the Dominican Republic, local authorities announced a warning about the possible flooding of 12 provinces of the country, since the expected rainfall by that time was 150 mm ^[34] . Civil defense bodies and military units in the southern regions of the island were in a state of full preparedness in the event of natural disasters ^{[31] [35]} .

During the passage of the Ana storm, the wind speed in St. Thomas (US Virgin Islands) reached 45 km / h with gusts of up to 65 km / h ^[36] . In Puerto Rico, heavy rains caused minor flooding, causing minor damage to the country's municipalities ^[37] . So, in people had to be resettled from several schools, and a number of highways in the metropolitan area were flooded for a while ^[2] . In the city of 44 mm of precipitation fell during the second half of August 17, the largest rainfall of 70 millimeters was recorded in the municipality of ^{[38] [39]} . Rains caused an increase in the general water level in the , and there were unfulfilled fears that the river might overflow. Throughout the island, about 6 thousand people were left without electricity due to trees that fell on the power line ^[36] . There were reports of tornadoes , tornadoes and tropical rains ^{[2] [40]} , weather forecasters predicted that in the mountainous regions of the Dominican Republic the precipitation level could exceed 150 mm, but no facts were recorded ^[41] .

In other words, due to its unstable, variable nature, Ana did not significantly damage the economy and infrastructure of the northeastern Caribbean Islands ^[37] , without justifying the gloomy forecasts of meteorologists.

The 2009 Ana Tropical Storm in the entire history of observations has become the sixth Atlantic cyclone with that name. The remaining five were in the seasons 1979 , 1985 , 1991 , 1997, and 2003 ^[42] . It is characteristic that all six cyclones of the same name were able to achieve the strength of a tropical storm, but not one gained the power of a hurricane. Without leaving behind any serious consequences, the storm of 2009 did not consolidate its name for itself and the next time the name Ana will be used in the season of Atlantic hurricanes in 2015 ^[43] .

• 2009 Atlantic Hurricane Season Timeline

•   Wikimedia Commons has media related to Ana (tropical storm, 2009)
• The National Hurricane Center's Advisory Archive for Tropical Storm Ana (English)