Typhoon Dolphin (2015)
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Typhoon Dolphin was a powerful
tropical cyclone A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its locat ...
that produced the first typhoon-force winds on
Guam Guam ( ; ) is an island that is an Territories of the United States, organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, Guam, Hagåtña, and the most ...
since Typhoon Pongsona in
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. The seventh
named storm Tropical cyclones and subtropical cyclones are named by various warning centers to simplify communication between forecasters and the general public regarding forecasts, watches and warnings. The names are intended to reduce confusion in the ...
of the
2015 Pacific typhoon season The 2015 Pacific typhoon season was a slightly above average season that produced twenty-seven tropical storms (including two that crossed over from the Eastern/Central Pacific), eighteen typhoons, and nine super typhoons. The season ran throug ...
, Dolphin formed on May 6 in the vicinity of the
Federated States of Micronesia The Federated States of Micronesia (, abbreviated FSM), or simply Micronesia, is an island country in Micronesia, a region of Oceania. The federation encompasses the majority of the Caroline Islands (excluding Palau) and consists of four Admin ...
(FSM). Moving eastward at first, the storm slowly organized before beginning a north and west-northwest trajectory. Dolphin intensified into a typhoon before passing between Guam and Rota on May 15, producing typhoon-force winds on both islands. It later rapidly intensified as it curved to the north. The American-based
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) designated Dolphin as a
super typhoon Since 1947, the Joint Typhoon Warning Center (JTWC) has classified all typhoons in the Tropical cyclone basins#Northwestern Pacific Ocean, Northwestern Pacific Ocean with wind speeds of at least —the equivalent of a strong Category 4 on th ...
, while the
Japan Meteorological Agency The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...
(JMA) estimated 10 minute sustained winds of . Dolphin turned to the northeast and weakened, becoming extratropical on May 20 and exiting the western Pacific basin on May 24. The storm first affected the FSM, notably
Pohnpei Pohnpei (formerly known as Ponape or Ascension, from Pohnpeian: "upon (''pohn'') a stone altar (''pei'')") is an island of the Senyavin Islands which are part of the larger Caroline Islands group. It belongs to Pohnpei State, one of the fou ...
where it dropped of rainfall over three days. The rains and gusty winds knocked down many trees on the island, one of which killed a person, and causing $1 million in damage (2015 
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). Dolphin passed between Guam and Rota, producing gusts of at
Andersen Air Force Base Andersen Air Force Base (Andersen AFB, AAFB) is a United States Air Force base located primarily within the village of Yigo in the United States territory of Guam. The host unit at Andersen AFB is the 36th Wing (36 WG), assigned to the Pacif ...
on northern Guam. The winds left 40% of the island without power and left at least 3,300 people without water. The storm also dropped heavy rainfall, flooding
Guam Memorial Hospital Guam Memorial Hospital is a rural general hospital located in Tamuning, Guam and is the only public hospital serving the island of Guam. The hospital has 161 licensed acute care beds, plus 40 beds at its off-site, long-term care Skilled Nursing F ...
. Dolphin damaged 390 houses, including nine that were destroyed, leaving 1,055 people homeless. With damage estimated at $10 million, the island was declared a disaster area. The typhoon also brushed Rota, causing $2.5 million in damage there, as well as Saipan.


Meteorological history

The origins of Dolphin were related to a strong westerly wind burst that also led to the formation of previous Typhoon Noul. Early on May 5, 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) began monitoring an area of deep convection approximately southwest of
Pohnpei Pohnpei (formerly known as Ponape or Ascension, from Pohnpeian: "upon (''pohn'') a stone altar (''pei'')") is an island of the Senyavin Islands which are part of the larger Caroline Islands group. It belongs to Pohnpei State, one of the fou ...
. It had a poorly-defined circulation and broad rainbands, while low to moderate
wind shear Wind shear (; also written 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 ...
and warm
sea surface temperature Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
s favored development. The convection quickly became better organized and more concentrated around the broad center, aided by increased outflow. The
Japan Meteorological Agency The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...
(JMA) classified the system as a tropical depression at 06:00 
UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...
on May 6 about southwest of Pohnpei. At 21:00 UTC that day, 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) also began issuing advisories on the system, classifying it as Tropical Depression 07W. After its formation, the depression moved slowly with the low-level flow, in what the JTWC described as an "atypical eastward direction". Wind shear in the region exposed the convection from the circulation early on May 7, although the thunderstorms increased the next day, mostly in the storm's northwest quadrant. A building
subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as subtropical ridges or highs. It is a high-pressur ...
turned the system more to the north. By May 8, the depression organized enough for the JTWC to upgrade it to a tropical storm. At 12:00 UTC on the next day, the JMA followed suit and upgraded the depression to Tropical Storm Dolphin. By that time, the system had developed rainbands spiraling around the circulation, although continued wind shear left the center exposed. Around that time, Dolphin passed about west of
Kosrae Kosrae ( ), formerly known as Kusaie or Strong's Island, is an island in the Caroline Islands archipelago, and States of Micronesia, state within the Federated States of Micronesia. It includes the main island of Kosrae, traditionally known as Ual ...
in the
Federated States of Micronesia The Federated States of Micronesia (, abbreviated FSM), or simply Micronesia, is an island country in Micronesia, a region of Oceania. The federation encompasses the majority of the Caroline Islands (excluding Palau) and consists of four Admin ...
(FSM), and over the next few days it passed near other small islands in the region. Despite the sheared structure, the storm developed an eye feature on May 11, indicative of further strengthening, while the storm was passing east of Pohnpei. That day, the shear began to decrease, allowing the outflow to improve and convection to blossom. Early on May 12, the JMA upgraded Dolphin to a severe tropical storm, estimating 10 minute
winds Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...
of . On May 12, Dolphin began moving steadily to the west-northwest. It developed a persistent
central dense overcast The central dense overcast, or CDO, of a tropical cyclone or strong subtropical cyclone is the large central area of thunderstorms surrounding its circulation center, caused by the formation of its eyewall. It can be round, angular, oval, or ir ...
over the center as conditions became increasingly favorable. At 00:00 UTC, the JMA and JTWC both upgraded Dolphin to typhoon status, based on a developing eye feature. The eye, initially only in diameter, became more defined in the center of the convection. The intensification trend was soon halted by a combination of moderate southerly wind shear and dry air from the west, causing the eye to become obscured on conventional satellite imagery. On May 15, the wind shear once again lessened. The compact core persisted during this time, although the center was slightly obscured. As the typhoon approached
Guam Guam ( ; ) is an island that is an Territories of the United States, organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, Guam, Hagåtña, and the most ...
, radar imagery tracked the eye underneath the deepest convection. Late on May 15, Dolphin passed between Guam and Rota, bringing its eyewall over both islands. After leaving the
Marianas Islands The Mariana Islands ( ; ), also simply the Marianas, are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly dormant volcanic mountains in the northwestern Pacific Ocean, between the 12th and 21st pa ...
, the eye of Dolphin became much larger as the storm developed strong outflow channels, both indicative of further strengthening. On May 16, the typhoon began
rapid deepening Rapid intensification (RI) is any process wherein a tropical cyclone strengthens very dramatically in a short period of time. Tropical cyclone forecasting agencies utilize differing thresholds for designating rapid intensification events, th ...
as it reached the western periphery of the ridge, causing it to turn more to the north. At 06:00 UTC that day, the JMA estimated peak 10 minute winds of . Based on the well-defined structure and Dvorak ratings of T7.0, the JTWC upgraded Dolphin to a
super typhoon Since 1947, the Joint Typhoon Warning Center (JTWC) has classified all typhoons in the Tropical cyclone basins#Northwestern Pacific Ocean, Northwestern Pacific Ocean with wind speeds of at least —the equivalent of a strong Category 4 on th ...
late on May 16 with 1 minute winds of . The approaching
westerlies The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes (about ...
turned Dolphin to the north and northeast on May 17 while also imparting unfavorable conditions, causing the eye and the convection to elongate and weaken. By May 18, increased wind shear had exposed the circulation as the winds continued to drop. After the convection decreased further, the JTWC discontinued advisories on Dolphin on May 19, once Dolphin was beginning to become extratropical near the Japanese island of
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. On the next day, the winds fell below typhoon force, and at 00:00 UTC on May 21, the JMA declared Dolphin extratropical. The storm accelerated to the northeast, passing through the
Aleutian Islands The Aleutian Islands ( ; ; , "land of the Aleuts"; possibly from the Chukchi language, Chukchi ''aliat'', or "island")—also called the Aleut Islands, Aleutic Islands, or, before Alaska Purchase, 1867, the Catherine Archipelago—are a chain ...
on May 22. The storm slowed once reaching the
Gulf of Alaska The Gulf of Alaska ( Tlingit: ''Yéil T'ooch’'') is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the ...
, turning eastward to cross the
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on May 24.


Preparations, impact, and aftermath

Early in Dolphin's duration, it moved through the eastern FSM. On Kosrae, winds peaked at . Later, the outer rainbands affected Pohnpei, producing a gust of , as well as heavy rainfall. Over three days, the precipitation reached of rainfall over three days, including in one day. This accounted for about one-third of Pohnpei's record monthly rainfall total of for May 2015. The high winds downed hundreds of trees, some of which fell onto cars and homes, and killed one person. One family in
Palikir Palikir () is the Capital city, capital city of the Federated States of Micronesia located in the western Pacific Ocean. A town of slightly under 5,000 residents, it is part of the larger Sokehs municipality, which had a population of 6,647 , ou ...
needed medical attention when a tree fell onto their house. Residents lost power and water access for up to two weeks. Many houses had damage to roofs, and about 200 homes on Pohnpei were damaged or destroyed. Crops also sustained damage from high waves causing salt intrusion, affecting
taro Taro (; ''Colocasia esculenta'') is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, stems and Petiole (botany), petioles. Taro corms are a ...
patches. Damage in the FSM was estimated at $1 million. In response to the damage, the FSM government declared Pohnpei as a state of emergency on June 8. The typhoon's westerly winds produced a swell that affected the
Marshall Islands The Marshall Islands, officially the Republic of the Marshall Islands, is an island country west of the International Date Line and north of the equator in the Micronesia region of the Northwestern Pacific Ocean. The territory consists of 29 c ...
, sinking several boats in
Kwajalein Atoll Kwajalein Atoll (; Marshallese language, Marshallese: ) is part of the Marshall Islands, Republic of the Marshall Islands (RMI). The southernmost and largest island in the atoll is named Kwajalein Island, which its majority English-speaking re ...
. In preparation for the cyclone, schools, businesses, and public transit were closed on Guam. The
Federal Emergency Management Agency The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Exec ...
(FEMA) deployed approximately 15 representatives to the island to mitigate the response time in the wake of the storm. Eight schools were opened as shelters, and more than 1,000 residents sought refuge during the height of the storm. Additional shelters were opened on the islands of Rota,
Tinian Tinian () is one of the three principal islands of the Commonwealth of the Northern Mariana Islands (CNMI). Together with uninhabited neighboring Aguiguan, it forms Tinian Municipality, one of the four constituent municipalities of the Northern ...
, and
Saipan Saipan () is the largest island and capital of the Northern Mariana Islands, an unincorporated Territories of the United States, territory of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Cens ...
in the
Northern Mariana Islands The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI), is an Territories of the United States, unincorporated territory and Commonwealth (U.S. insular area), commonwealth of the United States consistin ...
(CNMI), and nearly 200 people sought cover there. Airports and seaports between the three islands were shut down, causing flights to be canceled. Earlier in 2015, the Guam
Weather Forecast Office The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
created a
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page to help inform residents about typhoons; during Dolphin, the page received over 425,000 views. Passing just north of Guam, Dolphin produced the first typhoon-force winds on the island since 2002 during Typhoon Pongsona.
Andersen Air Force Base Andersen Air Force Base (Andersen AFB, AAFB) is a United States Air Force base located primarily within the village of Yigo in the United States territory of Guam. The host unit at Andersen AFB is the 36th Wing (36 WG), assigned to the Pacif ...
recorded sustained winds of , while gusts reached . In the central portion of the island, the NWS office recorded gusts of . The storm dropped torrential rainfall during its passage, reaching over at Andersen Air Force Base, of which fell within a 12-hour period. Wave heights offshore Guam topped . On Guam, the heavy rainfall caused flooding in areas lacking proper drainage. The
Guam Memorial Hospital Guam Memorial Hospital is a rural general hospital located in Tamuning, Guam and is the only public hospital serving the island of Guam. The hospital has 161 licensed acute care beds, plus 40 beds at its off-site, long-term care Skilled Nursing F ...
sustained about $1 million in damage from storm-related flooding. High winds left about 40% of Guam without power, mostly in the north and central portions of the island, although the outages were fixed within a few days. The power outages also disrupted generators for water wells, leaving 3,300 people without access to clean water; residents in some areas were under a
boil-water advisory A boil-water advisory (BWA), boil-water notice, boil-water warning, boil-water order, or boil order is a Public health, public-health advisory or directive issued by governmental or other health authorities to consumers when a community's drinkin ...
. Utility damage was estimated at $3 million. Businesses sustained $1.9 million in damage. Dolphin also caused $1.2 million worth of crop damage. The typhoon damaged over 7,000 banana trees as well as 39 of the endangered ironwood trees. Rough waves sank a boat at
Apra Harbor Apra Harbor, also called Port Apra, is a deep-water port on the western side of the United States territory of Guam. It is considered one of the best natural ports in the Pacific Ocean. The harbor is bounded by Cabras Island and the Glass Breakwat ...
, requiring workers to clean oil that escaped from the damaged vessel. Dolphin damaged 390 houses across Guam, of which 9 were destroyed and another 55 were severely damaged. This left 1,055 people homeless, mostly in the towns of
Yigo Yigo, Guam (; ) is the northernmost village of the United States territory of Guam, and is the location of Andersen Air Force Base. The municipality of Yigo is the largest village on the island in terms of area. It contains a number of populated pl ...
or
Dededo Dededo (; Spanish: ) is the most populated village in the United States territory of Guam. According to the U.S. Census Bureau, Dededo's population was just under 45,000 in 2020. The village is located on the coral plateau of Northern Guam. The gr ...
. Overall damage was estimated at nearly $10 million, prompting
Governor A governor is an politician, administrative leader and head of a polity or Region#Political regions, political region, in some cases, such as governor-general, governors-general, as the head of a state's official representative. Depending on the ...
Eddie Calvo Edward Jerome Baza Calvo (born August 29, 1961) is an American politician who served as the eighth governor of Guam from January 3, 2011 to January 7, 2019. A member of the Republican Party, Calvo was a five-term Senator within the Legislature ...
to declare a state of emergency. On June 5,
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Barack Obama Barack Hussein Obama II (born August 4, 1961) is an American politician who was the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, he was the first African American president in American history. O ...
signed a major disaster declaration for the territory, allowing for federal aid to be used. Ultimately, the government provided about $4.7 million in aid, mostly in public assistance. A federal grant provided 220 temporary jobs toward cleaning and repairing damage. On Rota to the north of Guam, Dolphin produced the first typhoon-force winds since 2004 during Chaba. The storm damaged many homes on the island. High winds knocked down trees and power lines, causing an island-wide power outage. Damage on Rota was estimated at $2.5 million. Continued high waves from the typhoon caused difficult conditions for ships trying to bring supplies to the country, after store supplies began running out. Workers quickly repaired the power outages and cleared roads of any storm debris. The government of the CNMI declared Rota a disaster area, meaning emergency funds could be allocated toward relief and reconstruction. On
Saipan Saipan () is the largest island and capital of the Northern Mariana Islands, an unincorporated Territories of the United States, territory of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Cens ...
to the north of Rota, wind gusts reached , while rainfall totaled . The remnants of Dolphin, in conjunction with previous Typhoon Noul, shifted the broader weather pattern to bring record warmth to Alaska, making the temperatures warmer than that of
Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...


See also

* Weather of 2015 *
Tropical cyclones in 2015 During 2015, tropical cyclones formed in seven major bodies of water, commonly known as tropical cyclone basins. Tropical cyclones will be assigned names by various weather agencies if they attain maximum sustained winds of . During the year, on ...
* Other tropical cyclones named Dolphin *
List of near-Equatorial tropical cyclones Typically, tropical cyclones form at least 5.0  degrees of latitude north and south of the equator, or at least 300 nautical miles (556  km, 345  mi) of the equator. Despite the presence of sufficiently warm sea surface temper ...
* List of typhoons in the Mariana Islands :*
Typhoon Isa Typhoon Isa was the first of a record eleven super typhoons to occur during the 1997 Pacific typhoon season. The second tropical cyclone of the season, Isa developed from a disturbance in the monsoon trough near the Caroline Islands on April 12. ...
(1997) – an early season typhoon that affected Guam in 1997 :*
Typhoon Chataan Typhoon Chataan, known in the Philippines as Super Typhoon Gloria, was the deadliest natural disaster in the history of Chuuk State, Chuuk, a state in the Federated States of Micronesia (FSM). The typhoon formed on June 28, 2002, near the FSM ...
(2002) – a deadly typhoon in 2002 that killed 47 people in the FSM and later struck Guam :*
Typhoon Choi-wan (2009) Typhoon Choi-wan was a powerful typhoon that became the first Category 5-equivalent super typhoon to form during the 2009 Pacific typhoon season. Forming on September 11, 2009, about to the east of Guam, the initial disturbance rapidly organized ...
– a strong typhoon that passed through the
Northern Marianas Islands The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI), is an unincorporated territory and commonwealth of the United States consisting of 14 islands in the northwestern Pacific Ocean.Lin, Tom C.W.Ame ...


References


External links


JMA General Information
on Typhoon Dolphin from Digital Typhoon
Satellite images of Typhoon Dolphin
from the U.S. Naval Research Laboratory {{DEFAULTSORT:Dolphin (2015) 2015 Pacific typhoon season Typhoons in Guam Typhoons in the Northern Mariana Islands 2015 in Guam 2015 in the Northern Mariana Islands May 2015 in the United States
Dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...