Hurricane Ioke
Encyclopedia
Hurricane Ioke was the strongest hurricane ever recorded in the Central Pacific
. The first storm to form in the Central Pacific in the 2006 Pacific hurricane season
, Ioke was a record breaking, long-lived and extremely powerful storm that traversed the Pacific for 19 days, reaching the equivalent of Category 5 status on the Saffir-Simpson Hurricane Scale
three times.
The cyclone developed from the Intertropical Convergence Zone
on August 20 far to the south of Hawaii
. Encountering warm waters, little wind shear
, and well-defined outflow
, Ioke intensified from a tropical depression to Category 4
status within 48 hours. Late on August 22 it rapidly weakened to Category 2 status before crossing over Johnston Atoll
. Two days later favorable conditions again allowed for rapid strengthening
, and Ioke attained Category 5 status on August 25 before crossing the International Date Line
. As it continued westward its intensity fluctuated, and on August 31 it passed near Wake Island
with winds of 155 mph (249.4 km/h). Ioke gradually weakened as it turned northwestward and northward, and by September 6 it had transitioned into an extratropical cyclone
. The remnants of Ioke accelerated northeastward and ultimately crossed into Alaska
.
Ioke did not affect any permanently populated areas in the Central Pacific or Western Pacific basins as a hurricane or a typhoon. A crew of 12 people rode out the hurricane in a hurricane-proof bunker on Johnston Atoll
; the crew estimated winds reached over 100 mph (160.9 km/h), which damaged trees on the island but did not impact the island's bird population. The hurricane left moderate damage on Wake Island
totaling $88 million (2006 USD), including blown off roofs and damaged buildings, though the infrastructure of the island was left intact; all military personnel were evacuated from the island. Later, the extratropical remnants of Ioke produced a severe storm surge along the Alaska
n coastline, causing beach erosion.
(ITCZ) spawned a tropical disturbance with a low-level circulation far to the southeast of Hawaii
in the middle of August 2006. Under the influence of a strong westward-moving subtropical ridge
to its north, the disturbance tracked nearly due westward, with deep convection in the region increasing and decreasing on a daily basis. It slowly became better organized, and early on August 20 the disturbance developed into Tropical Depression One-C while located about 775 mi (1,247.2 km) south of Honolulu, Hawaii
. At the time, there was no convection associated with the ITCZ within 10° Longitude
.
With wind shear
practically non-existent and sea surface temperatures of around 82 °F (27.8 °C), conditions favored strengthening, and operationally the cyclone was forecast to reach minimal hurricane status within four days before beginning to weaken. The depression attained tropical storm status within six hours of developing. The Central Pacific Hurricane Center
designated the system with the name Ioke (icon), Hawaiian
for the name Joyce. Subsequently, Ioke quickly strengthened, and by late on August 20 the storm developed a central dense overcast
and the beginnings of an eyewall
; early on August 21 the storm intensified into a hurricane, just 24 hours after first developing.
Hurricane Ioke steadily deepened as it continued west-northwestward, with better definition of the eye and deepening of the eyewall convection. Near the International Date Line
a frontal trough
turned the hurricane to the northwest, and after a period of rapid deepening
Ioke attained winds of 135 mph (217.3 km/h) early on August 22 while located about 280 mi (450.6 km) southeast of Johnston Atoll
. After maintaining Category 4 status on the Saffir-Simpson Hurricane Scale
for about 18 hours, southwesterly wind shear slightly disrupted the inner core of the hurricane, and Ioke quickly weakened to winds of about 105 mph (169 km/h). Late on August 22, the hurricane passed about 30 mi (48.3 km) south of Johnston Atoll, with the northeastern portion of the eyewall crossing the atoll early on August 23. After turning westward later in the day, wind shear began to decrease, allowing a second period of rapid deepening. By August 24 the hurricane maintained a 23 mi (37 km) closed eyewall, and on August 25 Ioke attained Category 5 status on the Saffir-Simpson Hurricane Scale while located about 970 mi (1,561.1 km) west-southwest of the Hawaiian Island of Kauai
.
After maintaining Category 5 status for about 18 hours, Hurricane Ioke weakened slightly due to an eyewall replacement cycle. Completing the cycle on August 26, the hurricane restrengthened to Category 5 status. The trough to its west tracked further away from the hurricane, allowing the subtropical ridge to build ahead of the hurricane which turned Ioke to the southwest. The overall environment remained very favorable for sustainment of the powerful cyclone. Strong upper-level cyclones far to its northwest provided outflow channels and light wind shear, with warm water temperatures along its path. With the conditions, the Geophysical Fluid Dynamics Laboratory
hurricane model predicted Ioke to reach winds of 220 mph (354.1 km/h), with a predicted minimum pressure of 860 mbar
(hPa). Early on August 27, the pressure dropped to 915 mbar (hPa), and shortly thereafter Ioke crossed the International Date Line
, becoming a 160 mph (257.5 km/h) typhoon.
Unofficially referred as a super typhoon
by the Joint Typhoon Warning Center
(JTWC), Ioke remained at the equivalence of a Category 5 hurricane for about 12 hours after crossing the Date Line. It then began a slight weakening trend on August 28, due to increased inflow from the ridge to its north. On August 29, the cyclone turned to the west and west-northwest while tracking around the periphery of the subtropical ridge, and Ioke again reached the equivalence of Category 5 status. The Japan Meteorological Agency
(JMA) assessed Ioke as attaining peak 10 minute sustained winds of 120 mph (193.1 km/h) on August 30. Later that day, the typhoon weakened to the equivalent of a Category 4 hurricane for the final time, and on August 31 Ioke passed very near Wake Island
with winds of about 155 mph (249.4 km/h).
By September 1, increased wind shear and drier air caused the eye of Ioke to become cloud-filled and elongated, and by September 2 Ioke was undergoing another eyewall replacement cycle. On September 2, Ioke passed about 50 mi (80.5 km) north of Minami Torishima
with winds of about 125 mph (201.2 km/h). Gradual weakening continued, and the typhoon steadily shifted its track to the northwest around the subtropical ridge. A deepening trough
turned Ioke to the north-northwest and north, and the cyclone weakened to a tropical storm a few hundred miles east of Japan
. After accelerating northeastward, the cyclone began losing tropical characteristics, and the JTWC declared Ioke as an extratropical cyclone
on September 5. The JMA maintained Ioke as a typhoon until a day later, and maintained Ioke as a tropical cyclone until it was declared extratropical midday on September 6. The extratropical remnants of Ioke were tracked by the JMA until September 7 when it was located near the Aleutian Islands of Alaska
. The storm deepened as it approached the Aleutians, and re-developed winds of hurricane-force. It entered the Bering Sea
on September 8, and after turning eastward crossed the Aleutian Islands and entered the Gulf of Alaska
. The extratropical remnants of Ioke dissipated near southeastern Alaska
on September 12.
issued a hurricane warning
for uninhabited territory of Johnston Island
, due to the uncertainty of whether anyone was on the island. A United States Air Force
vessel and a 12 person crew were on the island, and after securing their ship the crew took shelter in a hurricane-proof concrete bunker. There were no meteorological observations on the island, but the crew estimated tropical storm force winds lasted for about 27 hours with hurricane force winds lasting six to eight hours; peak wind gusts were estimated at 110 to 130 mph (177 to 209.2 km/h). The crew sustained no injuries, and their ship received only minor damage. Hurricane Ioke, with a portion of its eye crossing the atoll, left an estimated 15% of the palm trees on the island with their tops blown off, with some ironwood trees blown over; the island bird population was unaffected. The hurricane produced rough surf which washed away a portion of a sea wall and an adjacent road.
Under the threat of the typhoon for several days, two C-17 Globemaster III
airlift
ers evacuated between 188–200 military personnel from Wake Island
to Hawaii, the first full-scale evacuation of the island since Typhoon Sarah in 1967
. A buoy just east of the island recorded a pressure of 921.5 mbar as Ioke crossed directly over it. Before the typhoon passed just north of the island, an anemometer recorded hurricane force winds with a peak wind gust of 100 mph (160.9 km/h) before the instrument stopped reporting. Sustained winds were estimated to have reached 155 mph (249.4 km/h), with gusts to 190 mph (305.8 km/h). The minimum central pressure recorded on the island was 934 mbar at 0906 UTC
on August 31. The typhoon was expected to produce a storm surge
of 18 ft (5.5 m) and wave heights of 40 ft (12.2 m) along Wake Island, where the highest point is 20 ft (6.1 m). Additionally, heavy rainfall from the typhoon left buildings flooded, with 2 ft (0.6096 m) of standing water found several days after its passage.
The powerful winds of Typhoon Ioke caused extensive damage to the island's power grid, leaving most power lines to buildings and backup generators damaged. The combination of the winds and storm surge flooding damaged 70% of the buildings in the territory, many of which with moderate roof damage. All low-lying areas were described as being covered with sea water or sand, and the territory was left without running water. Communications were downed on the island, with satellite dishes and cables destroyed. Damage to the infrastructure was extensive, though repairable and less than expected. Damage on the island was estimated at $88 million (2006 USD, $90 million 2007 USD).
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On September 1, the Japan Meteorological Agency ordered the temporary evacuation of its staff on Minami Torishima
, under threat of the typhoon. The agency expected high waves and winds on the island. Facilities on the island were damaged, although it was repaired and fully operational within three weeks after the storm.
The extratropical remnant
of Ioke produced a storm surge and high surf in excess of 30 ft (9.1 m) along the southwestern coastline of Alaska
, which coincided with the astronomical high tide
; the combination led to minor flooding along Bristol Bay
and Yukon-Kuskokwim Delta
. Wind gusts peaked at 84 mph (135.2 km/h) in Unalaska
. The system produced moderate to heavy rainfall across the western portion of Alaska, including daily rainfall records of 1.15 inches (29 mm) at Bethel
and 0.67 inches (17 mm) at Kotzebue
. Rainfall continued into the southeastern portion of the state, contributing to above-normal rainfall totals near Juneau
.
in the Central North Pacific Ocean
, and the only one originating in the basin. With an estimated minimum central pressure of 915 mbar
(27.019 inHg
), the cyclone attained the lowest estimated surface pressure for any hurricane within the basin, surpassing the previous minimum set by Hurricane John
in 1994. Ioke maintained at least Category 4 status, or wind speeds greater than 131 mph (210.8 km/h), for 198 consecutive hours, which was the longest continuous time period at that intensity ever observed for any tropical cyclone anywhere on Earth. Additionally, the cyclone remained at the equivalence of a super typhoon
for 174 consecutive hours, which was also a record. As a result of its extended duration and intensity, Hurricane/Typhoon Ioke accrued an Accumulated cyclone energy
index of 82 104 kt2, which set a new worldwide record.
The United States Coast Guard
first performed an aerial assessment of damage on Wake Island
on September 2, three days after the typhoon struck. The flight indicated an overall damage smaller than expected, and reported a lack of oil spill or hazardous material leak. The U.S. Coast Guard arrived by boat with a team on September 7, with a preliminary damage assessment completed four days later; the team repaired a generator to provide power. A second crew analyzed the stability of the airfield, and after core tests workers cleared the runway to allow flights onto the territory. On September 13, a group of engineers restored power on the island. About a month after the cyclone, several buildings were operational.
The Central Pacific Hurricane Center requested the retirement of the name, and in April 2007, the name Ioke was retired, and replaced with Iopa.
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The first storm to form in the Central Pacific in the 2006 Pacific hurricane season
2006 Pacific hurricane season
The 2006 Pacific hurricane season was the most active Pacific hurricane season since 2000 producing 19 tropical storms or hurricanes. Eighteen developed within the National Hurricane Center area of warning responsibility, which is east of 140ºW, and one storm formed between 140ºW and the...
, Ioke was a record breaking, long-lived and extremely powerful storm that traversed the Pacific for 19 days, reaching the equivalent of Category 5 status on the Saffir-Simpson Hurricane Scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
three times.
The cyclone developed from the Intertropical Convergence Zone
Intertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
on August 20 far to the south of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. Encountering warm waters, little wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
, and well-defined outflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...
, Ioke intensified from a tropical depression to Category 4
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
status within 48 hours. Late on August 22 it rapidly weakened to Category 2 status before crossing over Johnston Atoll
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
. Two days later favorable conditions again allowed for rapid strengthening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
, and Ioke attained Category 5 status on August 25 before crossing the International Date Line
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
. As it continued westward its intensity fluctuated, and on August 31 it passed near Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
with winds of 155 mph (249.4 km/h). Ioke gradually weakened as it turned northwestward and northward, and by September 6 it had transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
. The remnants of Ioke accelerated northeastward and ultimately crossed into Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
.
Ioke did not affect any permanently populated areas in the Central Pacific or Western Pacific basins as a hurricane or a typhoon. A crew of 12 people rode out the hurricane in a hurricane-proof bunker on Johnston Atoll
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
; the crew estimated winds reached over 100 mph (160.9 km/h), which damaged trees on the island but did not impact the island's bird population. The hurricane left moderate damage on Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
totaling $88 million (2006 USD), including blown off roofs and damaged buildings, though the infrastructure of the island was left intact; all military personnel were evacuated from the island. Later, the extratropical remnants of Ioke produced a severe storm surge along the Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
n coastline, causing beach erosion.
Meteorological history
The Intertropical Convergence ZoneIntertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
(ITCZ) spawned a tropical disturbance with a low-level circulation far to the southeast of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
in the middle of August 2006. Under the influence of a strong westward-moving subtropical ridge
Subtropical ridge
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during...
to its north, the disturbance tracked nearly due westward, with deep convection in the region increasing and decreasing on a daily basis. It slowly became better organized, and early on August 20 the disturbance developed into Tropical Depression One-C while located about 775 mi (1,247.2 km) south of Honolulu, Hawaii
Honolulu, Hawaii
Honolulu is the capital and the most populous city of the U.S. state of Hawaii. Honolulu is the southernmost major U.S. city. Although the name "Honolulu" refers to the urban area on the southeastern shore of the island of Oahu, the city and county government are consolidated as the City and...
. At the time, there was no convection associated with the ITCZ within 10° Longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
.
With wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
practically non-existent and sea surface temperatures of around 82 °F (27.8 °C), conditions favored strengthening, and operationally the cyclone was forecast to reach minimal hurricane status within four days before beginning to weaken. The depression attained tropical storm status within six hours of developing. The Central Pacific Hurricane Center
Central Pacific Hurricane Center
The Central Pacific Hurricane Center of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central North Pacific Basin...
designated the system with the name Ioke (icon), Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...
for the name Joyce. Subsequently, Ioke quickly strengthened, and by late on August 20 the storm developed a central dense overcast
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
and the beginnings of an eyewall
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
; early on August 21 the storm intensified into a hurricane, just 24 hours after first developing.
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
a frontal trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
turned the hurricane to the northwest, and after a period of rapid deepening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
Ioke attained winds of 135 mph (217.3 km/h) early on August 22 while located about 280 mi (450.6 km) southeast of Johnston Atoll
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
. After maintaining Category 4 status on the Saffir-Simpson Hurricane Scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
for about 18 hours, southwesterly wind shear slightly disrupted the inner core of the hurricane, and Ioke quickly weakened to winds of about 105 mph (169 km/h). Late on August 22, the hurricane passed about 30 mi (48.3 km) south of Johnston Atoll, with the northeastern portion of the eyewall crossing the atoll early on August 23. After turning westward later in the day, wind shear began to decrease, allowing a second period of rapid deepening. By August 24 the hurricane maintained a 23 mi (37 km) closed eyewall, and on August 25 Ioke attained Category 5 status on the Saffir-Simpson Hurricane Scale while located about 970 mi (1,561.1 km) west-southwest of the Hawaiian Island of Kauai
Kauai
Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...
.
After maintaining Category 5 status for about 18 hours, Hurricane Ioke weakened slightly due to an eyewall replacement cycle. Completing the cycle on August 26, the hurricane restrengthened to Category 5 status. The trough to its west tracked further away from the hurricane, allowing the subtropical ridge to build ahead of the hurricane which turned Ioke to the southwest. The overall environment remained very favorable for sustainment of the powerful cyclone. Strong upper-level cyclones far to its northwest provided outflow channels and light wind shear, with warm water temperatures along its path. With the conditions, the Geophysical Fluid Dynamics Laboratory
Geophysical Fluid Dynamics Laboratory
The Geophysical Fluid Dynamics Laboratory is a laboratory in the National Oceanic and Atmospheric Administration /Office of Oceanic and Atmospheric Research . The current director is Dr. V...
hurricane model predicted Ioke to reach winds of 220 mph (354.1 km/h), with a predicted minimum pressure of 860 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(hPa). Early on August 27, the pressure dropped to 915 mbar (hPa), and shortly thereafter Ioke crossed the International Date Line
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
, becoming a 160 mph (257.5 km/h) typhoon.
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
by the Joint Typhoon Warning Center
Joint Typhoon Warning Center
The Joint Typhoon Warning Center is a joint United States Navy – United States Air Force task force located at the Naval Maritime Forecast Center in Pearl Harbor, Hawaii...
(JTWC), Ioke remained at the equivalence of a Category 5 hurricane for about 12 hours after crossing the Date Line. It then began a slight weakening trend on August 28, due to increased inflow from the ridge to its north. On August 29, the cyclone turned to the west and west-northwest while tracking around the periphery of the subtropical ridge, and Ioke again reached the equivalence of Category 5 status. The Japan Meteorological Agency
Japan Meteorological Agency
The or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
(JMA) assessed Ioke as attaining peak 10 minute sustained winds of 120 mph (193.1 km/h) on August 30. Later that day, the typhoon weakened to the equivalent of a Category 4 hurricane for the final time, and on August 31 Ioke passed very near Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
with winds of about 155 mph (249.4 km/h).
By September 1, increased wind shear and drier air caused the eye of Ioke to become cloud-filled and elongated, and by September 2 Ioke was undergoing another eyewall replacement cycle. On September 2, Ioke passed about 50 mi (80.5 km) north of Minami Torishima
Minami Torishima
or Marcus Island is an isolated Japanese coral atoll in the northwestern Pacific Ocean, located some SE of Tokyo and east of the closest Japanese island, South Iwo Jima of the Ogasawara Islands, and nearly on a straight line between Tokyo and Wake Island, which is east southeast...
with winds of about 125 mph (201.2 km/h). Gradual weakening continued, and the typhoon steadily shifted its track to the northwest around the subtropical ridge. A deepening trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
turned Ioke to the north-northwest and north, and the cyclone weakened to a tropical storm a few hundred miles east of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. After accelerating northeastward, the cyclone began losing tropical characteristics, and the JTWC declared Ioke as an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
on September 5. The JMA maintained Ioke as a typhoon until a day later, and maintained Ioke as a tropical cyclone until it was declared extratropical midday on September 6. The extratropical remnants of Ioke were tracked by the JMA until September 7 when it was located near the Aleutian Islands of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
. The storm deepened as it approached the Aleutians, and re-developed winds of hurricane-force. It entered the Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
on September 8, and after turning eastward crossed the Aleutian Islands and entered the Gulf of Alaska
Gulf of Alaska
The Gulf of Alaska 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 east, where Glacier Bay and the Inside Passage are found.The entire shoreline of the Gulf is...
. The extratropical remnants of Ioke dissipated near southeastern Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
on September 12.
Johnston Atoll
Late on August 21, about 24 hours prior to its closest approach, the Central Pacific Hurricane CenterCentral Pacific Hurricane Center
The Central Pacific Hurricane Center of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central North Pacific Basin...
issued a hurricane warning
Tropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
for uninhabited territory of Johnston Island
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
, due to the uncertainty of whether anyone was on the island. A United States Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
vessel and a 12 person crew were on the island, and after securing their ship the crew took shelter in a hurricane-proof concrete bunker. There were no meteorological observations on the island, but the crew estimated tropical storm force winds lasted for about 27 hours with hurricane force winds lasting six to eight hours; peak wind gusts were estimated at 110 to 130 mph (177 to 209.2 km/h). The crew sustained no injuries, and their ship received only minor damage. Hurricane Ioke, with a portion of its eye crossing the atoll, left an estimated 15% of the palm trees on the island with their tops blown off, with some ironwood trees blown over; the island bird population was unaffected. The hurricane produced rough surf which washed away a portion of a sea wall and an adjacent road.
Wake Island
C-17 Globemaster III
The Boeing C-17 Globemaster III is a large military transport aircraft. Developed for the United States Air Force from the 1980s to the early 1990s by McDonnell Douglas, the C-17 is used for rapid strategic airlift of troops and cargo to main operating bases or forward operating bases throughout...
airlift
Airlift
Airlift is the act of transporting people or cargo from point to point using aircraft.Airlift may also refer to:*Airlift , a suction device for moving sand and silt underwater-See also:...
ers evacuated between 188–200 military personnel from Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
to Hawaii, the first full-scale evacuation of the island since Typhoon Sarah in 1967
1967 Pacific typhoon season
The 1967 Pacific typhoon season has no official bounds; it ran year-round in 1967, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December...
. A buoy just east of the island recorded a pressure of 921.5 mbar as Ioke crossed directly over it. Before the typhoon passed just north of the island, an anemometer recorded hurricane force winds with a peak wind gust of 100 mph (160.9 km/h) before the instrument stopped reporting. Sustained winds were estimated to have reached 155 mph (249.4 km/h), with gusts to 190 mph (305.8 km/h). The minimum central pressure recorded on the island was 934 mbar at 0906 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on August 31. The typhoon was expected to produce a storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
of 18 ft (5.5 m) and wave heights of 40 ft (12.2 m) along Wake Island, where the highest point is 20 ft (6.1 m). Additionally, heavy rainfall from the typhoon left buildings flooded, with 2 ft (0.6096 m) of standing water found several days after its passage.
The powerful winds of Typhoon Ioke caused extensive damage to the island's power grid, leaving most power lines to buildings and backup generators damaged. The combination of the winds and storm surge flooding damaged 70% of the buildings in the territory, many of which with moderate roof damage. All low-lying areas were described as being covered with sea water or sand, and the territory was left without running water. Communications were downed on the island, with satellite dishes and cables destroyed. Damage to the infrastructure was extensive, though repairable and less than expected. Damage on the island was estimated at $88 million (2006 USD, $90 million 2007 USD).
Japan and Alaska
Minami Torishima
or Marcus Island is an isolated Japanese coral atoll in the northwestern Pacific Ocean, located some SE of Tokyo and east of the closest Japanese island, South Iwo Jima of the Ogasawara Islands, and nearly on a straight line between Tokyo and Wake Island, which is east southeast...
, under threat of the typhoon. The agency expected high waves and winds on the island. Facilities on the island were damaged, although it was repaired and fully operational within three weeks after the storm.
The extratropical remnant
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
of Ioke produced a storm surge and high surf in excess of 30 ft (9.1 m) along the southwestern coastline of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, which coincided with the astronomical high tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
; the combination led to minor flooding along Bristol Bay
Bristol Bay
Bristol Bay is the eastern-most arm of the Bering Sea, at 57° to 59° North 157° to 162° West in Southwest Alaska. Bristol Bay is 400 km long and 290 km, wide at its mouth...
and Yukon-Kuskokwim Delta
Yukon-Kuskokwim Delta
The Yukon–Kuskokwim Delta is one of the largest river deltas in the world, roughly the size of Oregon. It is located where the Yukon and Kuskokwim rivers empty into the Bering Sea on the west coast of the U.S. state of Alaska. The delta, which mostly consists of tundra, is protected as part of the...
. Wind gusts peaked at 84 mph (135.2 km/h) in Unalaska
Unalaska, Alaska
Unalaska is a city in the Aleutians West Census Area of the Unorganized Borough of the U.S. state of Alaska. Unalaska is located on Unalaska Island and neighboring Amaknak Island in the Aleutian Islands off of mainland Alaska....
. The system produced moderate to heavy rainfall across the western portion of Alaska, including daily rainfall records of 1.15 inches (29 mm) at Bethel
Bethel, Alaska
Bethel is a city located near the west coast of the U.S. state of Alaska, west of Anchorage. Accessible only by air and river, Bethel is the main port on the Kuskokwim River and is an administrative and transportation hub for the 56 villages in the Yukon-Kuskokwim Delta.Bethel is the largest...
and 0.67 inches (17 mm) at Kotzebue
Kotzebue, Alaska
As of the census of 2000, there were 3,082 people, 889 households, and 656 families residing in the city. The population density was 114.1 people per square mile . There were 1,007 housing units at an average density of 37.3 per square mile...
. Rainfall continued into the southeastern portion of the state, contributing to above-normal rainfall totals near Juneau
Juneau, Alaska
The City and Borough of Juneau is a unified municipality located on the Gastineau Channel in the panhandle of the U.S. state of Alaska. It has been the capital of Alaska since 1906, when the government of the then-District of Alaska was moved from Sitka as dictated by the U.S. Congress in 1900...
.
Records and aftermath
Hurricane Ioke became one of five hurricanes to reach Category 5 status on the Saffir-Simpson Hurricane ScaleSaffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
in the Central North Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and the only one originating in the basin. With an estimated minimum central pressure of 915 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(27.019 inHg
Inch of mercury
Inches of mercury, ' is a unit of measurement for pressure. It is still widely used for barometric pressure in weather reports, refrigeration and aviation in the United States, but is seldom used elsewhere....
), the cyclone attained the lowest estimated surface pressure for any hurricane within the basin, surpassing the previous minimum set by Hurricane John
Hurricane John (1994)
Hurricane John formed during the 1994 Pacific hurricane season and became both the longest-lasting and the farthest-traveling tropical cyclone ever observed...
in 1994. Ioke maintained at least Category 4 status, or wind speeds greater than 131 mph (210.8 km/h), for 198 consecutive hours, which was the longest continuous time period at that intensity ever observed for any tropical cyclone anywhere on Earth. Additionally, the cyclone remained at the equivalence of a super typhoon
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
for 174 consecutive hours, which was also a record. As a result of its extended duration and intensity, Hurricane/Typhoon Ioke accrued an Accumulated cyclone energy
Accumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
index of 82 104 kt2, which set a new worldwide record.
The United States Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
first performed an aerial assessment of damage on Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
on September 2, three days after the typhoon struck. The flight indicated an overall damage smaller than expected, and reported a lack of oil spill or hazardous material leak. The U.S. Coast Guard arrived by boat with a team on September 7, with a preliminary damage assessment completed four days later; the team repaired a generator to provide power. A second crew analyzed the stability of the airfield, and after core tests workers cleared the runway to allow flights onto the territory. On September 13, a group of engineers restored power on the island. About a month after the cyclone, several buildings were operational.
The Central Pacific Hurricane Center requested the retirement of the name, and in April 2007, the name Ioke was retired, and replaced with Iopa.
See also
- 2006 Pacific hurricane season2006 Pacific hurricane seasonThe 2006 Pacific hurricane season was the most active Pacific hurricane season since 2000 producing 19 tropical storms or hurricanes. Eighteen developed within the National Hurricane Center area of warning responsibility, which is east of 140ºW, and one storm formed between 140ºW and the...
- 2006 Pacific typhoon season2006 Pacific typhoon seasonThe 2006 Pacific typhoon season had no official bounds; it ran year-round in 2006, but most tropical cyclones tend to form in the northwestern Pacific Ocean between May and November...
- List of Category 5 Pacific hurricanes
- List of tropical cyclones
- Timeline of the 2006 Pacific hurricane seasonTimeline of the 2006 Pacific hurricane seasonThe 2006 Pacific hurricane season was the most active since the 2000 season, producing produced 21 tropical depressions; 19 of which became tropical storms or hurricanes...
- Timeline of the 2006 Pacific typhoon seasonTimeline of the 2006 Pacific typhoon seasonThe 2006 Pacific typhoon season had no official bounds; it ran year-round in 2006, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December...
- List of storms in the 2006 Pacific hurricane season
External links
- The CPHC's archive on Hurricane Ioke
- The CPHC's Best Track Data on Hurricane Ioke
- The JMA's Best Track Data on Typhoon Ioke (0612)
- The JMA's RSMC Best Track Data (Graphics) on Typhoon Ioke (0612)
- The JMA's RSMC Best Track Data (Text)
