September 2009 Vietnam tropical depression
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The September 2009 Vietnam tropical depression was a weak tropical depression that caused deadly flooding throughout central Vietnam in early September. Forming out of an area of low pressure on September 3, the depression hardly intensified as it meandered off the coast of Vietnam. Initially situated in a favorable environment,
convective Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convect ...
banding features began to develop and shower and thunderstorm activity formed near the center. On September 4, the
Joint Typhoon Warning Center The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...
issued a
Tropical Cyclone Formation Alert A Tropical Cyclone Formation Alert (TCFA) is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Fleet Weather Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming ...
; however, a sudden increase in
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...
caused the system to rapidly become disorganized, leading to the cancellation of the alert the next day. The system continued to slowly track off the coast of Vietnam, nearly dissipating on September 5, before becoming better organized. However, the depression remained weak, with the JTWC reporting on September 7 that the depression had dissipated, though the
Japan Meteorological Agency The , abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation an ...
(JMA) continued to issue advisories until the depression dissipated during September 9. Although the depression did not make landfall, the outer rainbands of the storm led to heavy rainfall throughout central Vietnam, peaking at . The ensuing floods killed at least six people and left three others missing. Large areas of cropland were inundated by the waters and numerous homes were damaged. In Quảng Nam Province, damages from the system were estimated at 45 billion ( VND; $2.52 million
USD The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
).


Meteorological history

The tropical depression originated from an
area of low pressure In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...
in the
South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phil ...
on September 1. Scattered
convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
was associated with the system, with the center devoid of showers and thunderstorms, as the low slowly tracked westward in a weak steering environment. Weak
outflow Outflow may refer to: *Capital outflow, the capital leaving a particular economy *Bipolar outflow, in astronomy, two continuous flows of gas from the poles of a star *Outflow (hydrology), the discharge of a lake or other reservoir system * Outflow ...
had formed along the northern edge of the system; however, intensification was not anticipated. The following day, convection began to form around the center of circulation and weak diffluence was noted around the system due to an
anticyclone An anticyclone is a weather phenomenon defined as a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere as viewed from abov ...
to the north. With low
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...
, convective banding features began to develop and the possibility of the system becoming a tropical cyclone increased. Early on September 3, the JMA began issuing advisories on the cyclone, classifying it as a tropical depression, the twentieth depression to be monitored by the JMA during the season. Although the system had a partially exposed low-level circulation center, the
Joint Typhoon Warning Center The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...
(JTWC) issued a
Tropical Cyclone Formation Alert A Tropical Cyclone Formation Alert (TCFA) is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Fleet Weather Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming ...
(TCFA) as the depression was likely to intensify as it was situated over high
sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...
s and in a favorable environment. However, by September 4, wind shear quickly increased and dislocated all of the convection associated with the depression from the center of circulation. This led to the JTWC canceling their TCFA as the environment was no longer favorable for development. The following day, the JTWC declared that the system had dissipated and was no longer a suspect area for tropical cyclone development as the system was virtually stationary off the coast of Vietnam. The JMA, on the other hand, continued to monitor the cyclone as a tropical depression. Although previously declaring that the system dissipated early on September 6, the JTWC began monitoring the re-developing system later that day. Convective banding had reformed, wind shear had decreased and the cyclone had less interaction with land as it slowly moved further into the South China Sea. However, late on September 8, both agencies declared that the depression had dissipated off the coast of Vietnam.


Impact

At least six people were killed, three were left missing and nine were injured by the depression throughout Vietnam. Rainfall from the storm exceeded , triggering widespread flash flooding. A maximum of fell in
Huế Huế () is the capital of Thừa Thiên Huế province in central Vietnam and was the capital of Đàng Trong from 1738 to 1775 and of Vietnam during the Nguyễn dynasty from 1802 to 1945. The city served as the old Imperial City and admi ...
. Sixty-one tons of fish were swept away during the floods and 8,700 hectares of rice fields were destroyed. The city of
Da Nang Nang or DanangSee also Danang Dragons ( ; vi, Đà Nẵng, ) is a class-1 municipality and the fifth-largest city in Vietnam by municipal population. It lies on the coast of the East Sea of Vietnam at the mouth of the Hàn River, and is one ...
sustained the worst flooding from the storm, with some areas reporting flood depths of . Schools throughout the area were closed as many residents were unable to pass through flooded streets. A sixth grader drowned in the city after the boat he was on overturned in flood waters. In Huế, a two-year-old drowned in flood waters on September 4. A large section of highway 14B, connecting Nam Đông and Huế was washed away. In Quảng Ngãi Province, two fishermen were left missing and five other people were injured by the storm. At least three homes sustained severe damage. Residents throughout Quảng Trị Province were advised to evacuate to safer areas as numerous landslides threatened homes. Numerous bridges were washed away by flood waters exceeding , isolating several communities. In the
Sơn Tịnh District ''Toxicodendron succedaneum'', the wax tree, Japanese Hazenoki tree (Sumac or wax tree), sơn in Vietnam or charão in Portuguese, is a flowering plant species in the genus '' Toxicodendron'' found in Asia, although it has been planted elsewhere ...
, 76 structures were destroyed by flooding and high winds. More than 200 homes were inundated by up to of flood waters in the communities of Hoa Tho Dong and Hoa Phat. At least one ship sank and officials lost contact with two others; officials stated that 1,178 boats were in the South China Sea in the storm. In the valleys of Tam Kỳ and Phú Ninh, nearly 1,000 homes were inundated by water. Roughly 20% of the 373,000 students starting school were told to remain home as their schools were closed due to flood waters. By September 7, officials in Quảng Nam Province estimated that property damages from the depression had reached 20 billion ( VND; $1.12 million
USD The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
) and agricultural losses amounted to 25 billion (VND; $1.4 million USD). Throughout other regions, at least 100 structures were damaged and more than 20,000 hectares of crops were submerged in flood waters. Damages to irrigation systems throughout the county amounted to 3 billion (VND; $168,000 USD).


See also

*
November 2016 Vietnam tropical depression The November 2016 Vietnam tropical depression caused heavy flooding throughout central and southern Vietnam. Forming out from a low-pressure system on November 3, the Japan Meteorological Agency (JMA) began monitoring it as a tropical depression. ...
*
Tropical Depression 18W (2013) Tropical Depression 18W was a tropical depression that impacted Vietnam, Laos and Thailand during mid September 2013. The system was first noted as a tropical depression on September 16, 2013, while it was located within the South China Sea to the ...
*
Typhoon Mirinae (2009) Typhoon Mirinae (), known in the Philippines as Typhoon Santi, was the 34th depression and the 14th typhoon in the 2009 Pacific typhoon season. It came several weeks after Typhoons Ketsana and Parma devastated the Philippines, thus adding addi ...
*
Tropical Storm Kajiki (2019) The 2019 Pacific typhoon season was the costliest Pacific typhoon season on record, just ahead of the previous year. The season featured fairly above-average tropical cyclone activity for the second consecutive year, producing 29 named storms, ...


References


External links


Japan Meteorological AgencyJoint Typhoon Warning Center

Vietnam's National Hydro-Meteorological Service
{{DEFAULTSORT:2009 09 Vietnam tropical depression 2009 Vietnam 2009 Vietnam Typhoons in Vietnam 2009 in Vietnam 2009 September Vietnam tropical depression 2009 disasters in Vietnam