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Hurricane Walaka

January 01, 1970

Hurricane Walaka was a Category 5 hurricane that brought high surf and a powerful storm surge to the Hawaiian Islands. Walaka was the nineteenth named storm, twelfth hurricane, eighth major hurricane, and second Category 5 hurricane of the 2018 Pacific hurricane season.[2]

Hurricane Walaka
Walaka at peak intensity south of Johnston Atoll on October 2
Meteorological history
FormedSeptember 29, 2018
ExtratropicalOctober 6, 2018
DissipatedOctober 7, 2018
Category 5 major hurricane
1-minute sustained (SSHWS/NWS)
Highest winds160 mph (260 km/h)
Lowest pressure921 mbar (hPa); 27.20 inHg
Overall effects
FatalitiesNone
DamageMinimal
Areas affectedJohnston Atoll, Northwestern Hawaiian Islands, East Island
IBTrACS / [1]
Part of the 2018 Pacific hurricane season

The tropical cyclone originated from an area of low pressure that formed around 1,600 mi (2,600 km) south-southeast of Hawaii on September 24. The system tracked westward and moved into the Central Pacific Basin about a day later. The disturbance continued westward over the next few days, organizing into a tropical depression on September 29. Later that day, the system strengthened into a tropical storm, receiving the name Walaka. The storm then rapidly intensified, becoming a hurricane on September 30 and a major hurricane by October 1. The cyclone took on a more northward track under the influence of a low-pressure system located to the north. Walaka peaked as a Category 5 hurricane, with winds of 160 mph (260 km/h) and a pressure of 921 mbar (27.20 inHg), early on October 2. An eyewall replacement cycle caused the hurricane to weaken, though it remained a major hurricane for the next couple of days. Afterward, less favorable conditions caused a steady weakening of the hurricane, and Walaka became extratropical on October 6, well to the north of the Hawaiian Islands. The storm's remnants accelerated northeastward, before dissipating on October 7.

Although the hurricane did not hit any major landmasses, it passed very close to the unpopulated Johnston Atoll as a strong Category 4 hurricane, where a hurricane warning was issued in advance of the storm. Four scientists there intended to ride out the storm on the island, but were evacuated before the storm hit. Walaka neared the far Northwestern Hawaiian Islands, but weakened considerably as it did so. East Island in the French Frigate Shoals suffered a direct hit and was completely destroyed. The storm caused significant damage to the nesting grounds for multiple endangered species; coral reefs in the region suffered considerable damage, displacing the local fish population. Several dozen people had to be rescued off the southern shore of Oahu as the storm brought high surf to the main Hawaiian Islands.

Meteorological history edit

 
Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Map key
Saffir–Simpson scale
  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown
Storm type
  Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

On September 22, 2018, the National Hurricane Center (NHC) forecast that a low-pressure area would form around 130–140° west.[3] Two days later, a trough – an elongated region of low atmospheric pressure – formed around 1,600 mi (2,600 km) south-southeast of Hilo, Hawaii.[4] The disturbance entered the Central Pacific Basin on September 26 as a mixture of low-level clouds and larger cumulus clouds. A subtropical ridge located north of the Hawaiian Islands caused the system to track westward over the next few days. A surface low formed by 12:00 UTC on September 27 as the system was located 805 mi (1,296 km) southeast of Hilo. The system became Tropical Depression One-C around 12:00 UTC on September 29 while it was around 690 mi (1,110 km) south of Honolulu, Hawaii.[1] Convection or thunderstorm activity formed near the system's low-level circulation center, and a banding feature – significantly elongated, curved bands of rain clouds – became established over the southern and eastern portions of the depression. Six hours later, the system strengthened into a tropical storm, receiving the name Walaka from the Central Pacific Hurricane Center (CPHC).[1][5]

The nascent tropical storm was located in an environment of warm 84–86 °F (29–30 °C) sea surface temperatures, low vertical wind shear, and humid air.[1][5] After forming, the cyclone's banding features degraded, although its convection persisted. Meanwhile, the ridge continued to steer Walaka westward.[6] Around this time, Walaka began a stint of rapid intensification.[1] Convection became more abundant around the storm's low-level center during the morning of September 30.[7] Walaka's cloud tops cooled;[8] the tropical cyclone intensified into a hurricane by 18:00 UTC.[1] A cloud-filled eye emerged on visible satellite imagery by early October 1 as Walaka continued to strengthen.[9] Walaka became a Category 3 major hurricane around 12:00 UTC on October 1, the fourth storm to do so in the Central Pacific in 2018.[1] At that time, the hurricane possessed a prominent eye surrounded by a sizeable ring of cold clouds. Walaka turned towards the west-northwest as it moved around the southwestern edge of the ridge.[10] Walaka peaked as a Category 5 hurricane, with maximum sustained winds of 160 mph (260 km/h) and a minimum central pressure of 921 mbar (27.20 inHg), at 00:00 UTC on October 2. Walaka's peak intensity made it the second Category 5 hurricane of the 2018 Pacific hurricane season.[1] Around that time, the cyclone had a clear, 23-mile (37 km) wide eye surrounded by cool cloud tops.[11] Meanwhile, microwave imagery and ASCAT data showed the formation of concentric eyewalls, signaling that an eyewall replacement cycle had commenced. A strengthening upper-level low located north of Walaka was causing the hurricane to begin a more northward track.[1][12][13]

 
Walaka as a minimal Category 1 hurricane early on October 5

Walaka maintained its peak intensity for six hours before beginning to decay as a result of the eyewall replacement cycle. The cyclone continued to track northward under the influence of the upper-level low.[1][13] The hurricane weakened to a minimal Category 4 hurricane by 00:00 UTC on October 3. By that time, Walaka's eye had degraded on satellite imagery;[1] the eye had become cloud-filled, and the clouds making up the eyewall and central dense overcast had warmed.[14][15] Walaka passed about 45 mi (72 km) west of Johnston Island around 03:00 UTC.[16] After completing the eyewall cycle, Walaka reintensified slightly, reaching a secondary peak of 145 mph (233 km/h) around 12:00 UTC on October 3.[1] The cyclone's eye became increasingly delineated as the clouds comprising the eyewall cooled. Although the storm had restrengthened, increasing wind shear was thinning the northwestern eyewall.[17] Soon after, Walaka began to weaken once more as it advanced north-northeastward. Later on October 3, the western and southwestern eyewall eroded as a result of the wind shear. At the same time, upper-level cirrus outflow was disrupted in the southwestern and northeastern portions of the storm.[18] The already strong wind shear increased even further, peaking at 54 mph (87 km/h) around 00:00 UTC. Walaka's eye disappeared from visible satellite imagery and the southwestern portion of the low-level center became uncovered.[19]

Walaka moved across the Papahanaumokuakea Marine National Monument near Brooks Banks, a submerged volcanic cone, around 06:20 UTC on October 4. At that time, the Category 3 hurricane was located approximately 35 mi (56 km) west-northwest of the French Frigate Shoals.[1] Environmental conditions deteriorated even further on October 4 as sea surface temperatures fell below 81 °F (27 °C) and ocean heat content decreased.[20] This caused Walaka to rapidly weaken; the hurricane fell below major hurricane intensity around 12:00 UTC and was a minimal Category 1 hurricane by 00:00 UTC on October 5.[1] Early on October 5, Walaka turned towards the northwest as it traced the northern boundary of the upper-level low. Convection associated with the storm continued to dissipate; the remaining thunderstorm activity was displaced northeast of the storm's low-level center.[21] The wind shear abated later on October 5, although sea surface temperatures along the remainder of the tropical storm's track were cooler than 77 °F (25 °C). As a result of the decreased shear, Walaka's low-level center was temporarily recovered by convection and the weakening trend slowed as the storm continued north-northwest.[1][22] By late October 5, the low-level center was completely exposed once more and the remaining convection had all but dissipated. Walaka turned towards the northeast, steered by an upper-level trough.[1][23] Walaka transitioned into an extratropical cyclone around 12:00 UTC on October 6 after having been deprived of thunderstorm activity.[1][24] The extratropical cyclone tracked over the open sea and dissipated by 18:00 UTC on October 7.[1]

Unrelated to Walaka, Typhoon Kong-rey was a Category 5-equivalent super typhoon and Walaka had Category 5 hurricane intensity at the same time, marking the first time since 2005 when two tropical cyclones of Category 5 strength existed simultaneously in the Northern Hemisphere.[25]

Preparations and impact edit

 
The 11-acre (4.5-hectare) East Island was completely swept away by the hurricane's storm surge. The majority of sediment was deposited to the north across coral reefs.

As Walaka approached the Northwestern Hawaiian Islands, a hurricane watch was issued for Johnston Atoll on September 30 and was upgraded to a hurricane warning on October 1. Early on October 2, a hurricane watch was issued for Nihoa to French Frigate Shoals to Maro Reef. Later in the day, a hurricane warning was issued for French Frigate Shoals to Maro Reef and a tropical storm warning was issued for Nihoa to French Frigate Shoals.[1] A crew of four scientists on the isolated Johnston Atoll had planned on riding out the storm in an evacuation shelter until the United States Fish and Wildlife Service sought an emergency evacuation on October 1. The United States Coast Guard flew a plane from Kalaeloa Airport to evacuate the personnel the next day.[26][27] Seven researchers studying Hawaiian monk seals and green sea turtles on French Frigate Shoals were evacuated to Honolulu on October 2.[28]

Walaka struck the northwestern Hawaiian Islands as a Category 3 hurricane on October 4.[1] A powerful storm surge accompanied the hurricane as it traversed the French Frigate Shoals. The small, low-lying East Island suffered a direct hit and was completely destroyed, sediment being scattered across coral reefs to the north. The island had served as one of the major nesting locations for the endangered green sea turtles, and critically endangered Hawaiian monk seals.[29] An estimated 19 percent of 2018's sea turtle nests on the island were lost, but all adult females tending the nests left before the storm. Approximately half of Hawaii's green sea turtles nested on the island, and Charles Littnan – director of the National Oceanic and Atmospheric Administration's protected species division – stated it would take years for the implications of the island's loss to be fully understood.[30] By August 2019, satellite imagery showed that sand was beginning to reaccumulate on East Island.[31] Coral reefs near the French Frigate Shoals, Lisianski Island, and the Pearl and Hermes Atoll were substantially damaged, displacing the native fish population.[1]

Swells from Hurricane Walaka brought high surf to the main Hawaiian Islands on October 4. Walaka produced a surf that was 6–12 ft (1.8–3.7 m) high along the southern and western shores of Niihau, Kauai, and Oahu. The southern shores of Molokai, Lanai, and Maui experienced waves approximately 5–8 ft (1.5–2.4 m) in height. Hawaii's Big Island endured a surf that was 6–10 ft (1.8–3.0 m) high on its western shores.[32] At least 81 people had to be rescued by lifeguards off the southern shore of Oahu.[33]

See also edit

References edit

  1. ^ a b c d e f g h i j k l m n o p q r s t u Houston, Sam; Birchard, Thomas (June 9, 2020). Tropical Cyclone Report: Hurricane Walaka (PDF) (Report). Central Pacific Hurricane Center. (PDF) from the original on June 12, 2020. Retrieved September 4, 2020.
  2. ^ National Hurricane Center; Hurricane Research Division; Central Pacific Hurricane Center (April 4, 2023). "The Northeast and North Central Pacific hurricane database 1949–2022". United States National Oceanic and Atmospheric Administration's National Weather Service. A guide on how to read the database is available here.   This article incorporates text from this source, which is in the public domain.
  3. ^ Zelinsky, David (September 22, 2018). Tropical Weather Outlook: Eastern Pacific [500 PM PDT Mon Sep 22 2018] (Report). NHC Graphical Outlook Archive. National Hurricane Center. from the original on September 28, 2018. Retrieved August 30, 2020.
  4. ^ Zelinsky, David (September 24, 2018). Tropical Weather Outlook: Eastern Pacific [500 PM PDT Mon Sep 24 2018] (Report). NHC Graphical Outlook Archive. National Hurricane Center. from the original on September 30, 2018. Retrieved August 31, 2020.
  5. ^ a b Wroe, Derek (September 29, 2018). Tropical Storm Walaka Discussion Number 1 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 6, 2020.
  6. ^ Wroe, Derek (September 30, 2018). Tropical Storm Walaka Discussion Number 2 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 7, 2020.
  7. ^ Jelsema, Jon (September 30, 2018). Tropical Storm Walaka Discussion Number 3 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 7, 2020.
  8. ^ Powell, Jeff (September 30, 2018). Tropical Storm Walaka Discussion Number 5 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 7, 2020.
  9. ^ Powell, Jeff (October 1, 2018). Hurricane Walaka Discussion Number 6 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 7, 2020.
  10. ^ Jelsema, Jon (October 1, 2018). Hurricane Walaka Discussion Number 8 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 7, 2020.
  11. ^ Kodama, Kevin (October 1, 2018). Hurricane Walaka Discussion Number 9 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 8, 2020.
  12. ^ Kodama, Kevin (October 2, 2018). Hurricane Walaka Discussion Number 10 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 8, 2020.
  13. ^ a b Jelsema, Jon (October 2, 2018). Hurricane Walaka Discussion Number 12 (Report). Central Pacific Hurricane Center. from the original on July 29, 2019. Retrieved September 8, 2020.
  14. ^ Brenchley, Chris (October 2, 2018). Hurricane Walaka Discussion Number 13 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 8, 2020.
  15. ^ Ballard, Robert (October 3, 2018). Hurricane Walaka Discussion Number 14...Corrected (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 8, 2020.
  16. ^ Ballard, Robert (October 3, 2018). Hurricane Walaka Advisory Number 14 (Report). Central Pacific Hurricane Center. from the original on October 28, 2020. Retrieved October 26, 2020.
  17. ^ Houston, Sam (October 3, 2018). Hurricane Walaka Discussion Number 16...Corrected (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  18. ^ Brenchley, Chris (October 3, 2018). Hurricane Walaka Discussion Number 17 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  19. ^ Brenchley, Chris (October 4, 2018). Hurricane Walaka Discussion Number 18 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  20. ^ Houston, Sam (October 4, 2018). Hurricane Walaka Discussion Number 20 (Report). Central Pacific Hurricane Center. from the original on July 29, 2019. Retrieved September 9, 2020.
  21. ^ Wroe, Derek (October 5, 2018). Hurricane Walaka Discussion Number 22 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  22. ^ Jelsema, Jon (October 5, 2018). Tropical Storm Walaka Discussion Number 23 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  23. ^ Powell, Jeff (October 5, 2018). Tropical Storm Walaka Discussion Number 25 (Report). Central Pacific Hurricane Center. from the original on September 9, 2020. Retrieved September 9, 2020.
  24. ^ Houston, Sam (October 6, 2018). Post-Tropical Cyclone Walaka Discussion Number 28 (Report). Central Pacific Hurricane Center. from the original on July 29, 2019. Retrieved September 9, 2020.
  25. ^ Matthew Cappucci (October 2, 2018). "Two monster tropical cyclones are raging in the Pacific Ocean". The Washington Post. from the original on December 24, 2018. Retrieved October 14, 2018.
  26. ^ Magee, David (October 2, 2018). "Hurricane Walaka Threatens Seabirds With Direct Hit on Johnston Atoll in Pacific". Newsweek. from the original on October 8, 2018. Retrieved October 8, 2018.
  27. ^ "Coast Guard evacuates Fish and Wildlife crew off Johnston Atoll ahead of Hurricane Walaka". Coast Guard News. October 2, 2018. from the original on October 9, 2018. Retrieved October 8, 2018.
  28. ^ . The New York Times. Associated Press. October 3, 2018. Archived from the original on October 12, 2018. Retrieved October 12, 2018.
  29. ^ Milman, Oliver (October 24, 2018). "Hawaiian island erased by powerful hurricane: 'The loss is a huge blow'". The Guardian. from the original on October 24, 2018. Retrieved October 24, 2018.
  30. ^ D’Angelo, Chris (October 23, 2018). "Remote Hawaiian Island Wiped Off The Map". Huffington Post. from the original on October 23, 2018. Retrieved October 23, 2018.
  31. ^ Eagle, Nathan (August 15, 2019). "NOAA: 'The Reefs Weren't Damaged, They Were Just Gone'". Honolulu Civil Beat. from the original on November 7, 2020. Retrieved October 26, 2020.
  32. ^ Event: High Surf in Kohala, Hawaii [2018-10-04 06:00 HST-10] (Report). Storm Events Database. National Centers for Environmental Information. from the original on November 20, 2021. Retrieved October 26, 2020.
  33. ^ Gonzales, Melody (October 4, 2018). . KITV 4 Island News. ABC. Archived from the original on October 29, 2020. Retrieved October 26, 2020.

External links edit

 
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  • The Central Pacific Hurricane Center's advisory archive on Hurricane Walaka

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January 01, 1970
hurricane, walaka, category, hurricane, that, brought, high, surf, powerful, storm, surge, hawaiian, islands, walaka, nineteenth, named, storm, twelfth, hurricane, eighth, major, hurricane, second, category, hurricane, 2018, pacific, hurricane, season, walaka,. Hurricane Walaka was a Category 5 hurricane that brought high surf and a powerful storm surge to the Hawaiian Islands Walaka was the nineteenth named storm twelfth hurricane eighth major hurricane and second Category 5 hurricane of the 2018 Pacific hurricane season 2 Hurricane Walaka Walaka at peak intensity south of Johnston Atoll on October 2Meteorological historyFormedSeptember 29 2018ExtratropicalOctober 6 2018DissipatedOctober 7 2018Category 5 major hurricane1 minute sustained SSHWS NWS Highest winds160 mph 260 km h Lowest pressure921 mbar hPa 27 20 inHgOverall effectsFatalitiesNoneDamageMinimalAreas affectedJohnston Atoll Northwestern Hawaiian Islands East IslandIBTrACS 1 Part of the 2018 Pacific hurricane season The tropical cyclone originated from an area of low pressure that formed around 1 600 mi 2 600 km south southeast of Hawaii on September 24 The system tracked westward and moved into the Central Pacific Basin about a day later The disturbance continued westward over the next few days organizing into a tropical depression on September 29 Later that day the system strengthened into a tropical storm receiving the name Walaka The storm then rapidly intensified becoming a hurricane on September 30 and a major hurricane by October 1 The cyclone took on a more northward track under the influence of a low pressure system located to the north Walaka peaked as a Category 5 hurricane with winds of 160 mph 260 km h and a pressure of 921 mbar 27 20 inHg early on October 2 An eyewall replacement cycle caused the hurricane to weaken though it remained a major hurricane for the next couple of days Afterward less favorable conditions caused a steady weakening of the hurricane and Walaka became extratropical on October 6 well to the north of the Hawaiian Islands The storm s remnants accelerated northeastward before dissipating on October 7 Although the hurricane did not hit any major landmasses it passed very close to the unpopulated Johnston Atoll as a strong Category 4 hurricane where a hurricane warning was issued in advance of the storm Four scientists there intended to ride out the storm on the island but were evacuated before the storm hit Walaka neared the far Northwestern Hawaiian Islands but weakened considerably as it did so East Island in the French Frigate Shoals suffered a direct hit and was completely destroyed The storm caused significant damage to the nesting grounds for multiple endangered species coral reefs in the region suffered considerable damage displacing the local fish population Several dozen people had to be rescued off the southern shore of Oahu as the storm brought high surf to the main Hawaiian Islands Contents 1 Meteorological history 2 Preparations and impact 3 See also 4 References 5 External linksMeteorological history edit nbsp Map plotting the storm s track and intensity according to the Saffir Simpson scaleMap keySaffir Simpson scale Tropical depression 38 mph 62 km h Tropical storm 39 73 mph 63 118 km h Category 1 74 95 mph 119 153 km h Category 2 96 110 mph 154 177 km h Category 3 111 129 mph 178 208 km h Category 4 130 156 mph 209 251 km h Category 5 157 mph 252 km h Unknown Storm type nbsp Tropical cyclone nbsp Subtropical cyclone nbsp Extratropical cyclone remnant low tropical disturbance or monsoon depression On September 22 2018 the National Hurricane Center NHC forecast that a low pressure area would form around 130 140 west 3 Two days later a trough an elongated region of low atmospheric pressure formed around 1 600 mi 2 600 km south southeast of Hilo Hawaii 4 The disturbance entered the Central Pacific Basin on September 26 as a mixture of low level clouds and larger cumulus clouds A subtropical ridge located north of the Hawaiian Islands caused the system to track westward over the next few days A surface low formed by 12 00 UTC on September 27 as the system was located 805 mi 1 296 km southeast of Hilo The system became Tropical Depression One C around 12 00 UTC on September 29 while it was around 690 mi 1 110 km south of Honolulu Hawaii 1 Convection or thunderstorm activity formed near the system s low level circulation center and a banding feature significantly elongated curved bands of rain clouds became established over the southern and eastern portions of the depression Six hours later the system strengthened into a tropical storm receiving the name Walaka from the Central Pacific Hurricane Center CPHC 1 5 The nascent tropical storm was located in an environment of warm 84 86 F 29 30 C sea surface temperatures low vertical wind shear and humid air 1 5 After forming the cyclone s banding features degraded although its convection persisted Meanwhile the ridge continued to steer Walaka westward 6 Around this time Walaka began a stint of rapid intensification 1 Convection became more abundant around the storm s low level center during the morning of September 30 7 Walaka s cloud tops cooled 8 the tropical cyclone intensified into a hurricane by 18 00 UTC 1 A cloud filled eye emerged on visible satellite imagery by early October 1 as Walaka continued to strengthen 9 Walaka became a Category 3 major hurricane around 12 00 UTC on October 1 the fourth storm to do so in the Central Pacific in 2018 1 At that time the hurricane possessed a prominent eye surrounded by a sizeable ring of cold clouds Walaka turned towards the west northwest as it moved around the southwestern edge of the ridge 10 Walaka peaked as a Category 5 hurricane with maximum sustained winds of 160 mph 260 km h and a minimum central pressure of 921 mbar 27 20 inHg at 00 00 UTC on October 2 Walaka s peak intensity made it the second Category 5 hurricane of the 2018 Pacific hurricane season 1 Around that time the cyclone had a clear 23 mile 37 km wide eye surrounded by cool cloud tops 11 Meanwhile microwave imagery and ASCAT data showed the formation of concentric eyewalls signaling that an eyewall replacement cycle had commenced A strengthening upper level low located north of Walaka was causing the hurricane to begin a more northward track 1 12 13 nbsp Walaka as a minimal Category 1 hurricane early on October 5 Walaka maintained its peak intensity for six hours before beginning to decay as a result of the eyewall replacement cycle The cyclone continued to track northward under the influence of the upper level low 1 13 The hurricane weakened to a minimal Category 4 hurricane by 00 00 UTC on October 3 By that time Walaka s eye had degraded on satellite imagery 1 the eye had become cloud filled and the clouds making up the eyewall and central dense overcast had warmed 14 15 Walaka passed about 45 mi 72 km west of Johnston Island around 03 00 UTC 16 After completing the eyewall cycle Walaka reintensified slightly reaching a secondary peak of 145 mph 233 km h around 12 00 UTC on October 3 1 The cyclone s eye became increasingly delineated as the clouds comprising the eyewall cooled Although the storm had restrengthened increasing wind shear was thinning the northwestern eyewall 17 Soon after Walaka began to weaken once more as it advanced north northeastward Later on October 3 the western and southwestern eyewall eroded as a result of the wind shear At the same time upper level cirrus outflow was disrupted in the southwestern and northeastern portions of the storm 18 The already strong wind shear increased even further peaking at 54 mph 87 km h around 00 00 UTC Walaka s eye disappeared from visible satellite imagery and the southwestern portion of the low level center became uncovered 19 Walaka moved across the Papahanaumokuakea Marine National Monument near Brooks Banks a submerged volcanic cone around 06 20 UTC on October 4 At that time the Category 3 hurricane was located approximately 35 mi 56 km west northwest of the French Frigate Shoals 1 Environmental conditions deteriorated even further on October 4 as sea surface temperatures fell below 81 F 27 C and ocean heat content decreased 20 This caused Walaka to rapidly weaken the hurricane fell below major hurricane intensity around 12 00 UTC and was a minimal Category 1 hurricane by 00 00 UTC on October 5 1 Early on October 5 Walaka turned towards the northwest as it traced the northern boundary of the upper level low Convection associated with the storm continued to dissipate the remaining thunderstorm activity was displaced northeast of the storm s low level center 21 The wind shear abated later on October 5 although sea surface temperatures along the remainder of the tropical storm s track were cooler than 77 F 25 C As a result of the decreased shear Walaka s low level center was temporarily recovered by convection and the weakening trend slowed as the storm continued north northwest 1 22 By late October 5 the low level center was completely exposed once more and the remaining convection had all but dissipated Walaka turned towards the northeast steered by an upper level trough 1 23 Walaka transitioned into an extratropical cyclone around 12 00 UTC on October 6 after having been deprived of thunderstorm activity 1 24 The extratropical cyclone tracked over the open sea and dissipated by 18 00 UTC on October 7 1 Unrelated to Walaka Typhoon Kong rey was a Category 5 equivalent super typhoon and Walaka had Category 5 hurricane intensity at the same time marking the first time since 2005 when two tropical cyclones of Category 5 strength existed simultaneously in the Northern Hemisphere 25 Preparations and impact edit nbsp The 11 acre 4 5 hectare East Island was completely swept away by the hurricane s storm surge The majority of sediment was deposited to the north across coral reefs As Walaka approached the Northwestern Hawaiian Islands a hurricane watch was issued for Johnston Atoll on September 30 and was upgraded to a hurricane warning on October 1 Early on October 2 a hurricane watch was issued for Nihoa to French Frigate Shoals to Maro Reef Later in the day a hurricane warning was issued for French Frigate Shoals to Maro Reef and a tropical storm warning was issued for Nihoa to French Frigate Shoals 1 A crew of four scientists on the isolated Johnston Atoll had planned on riding out the storm in an evacuation shelter until the United States Fish and Wildlife Service sought an emergency evacuation on October 1 The United States Coast Guard flew a plane from Kalaeloa Airport to evacuate the personnel the next day 26 27 Seven researchers studying Hawaiian monk seals and green sea turtles on French Frigate Shoals were evacuated to Honolulu on October 2 28 Walaka struck the northwestern Hawaiian Islands as a Category 3 hurricane on October 4 1 A powerful storm surge accompanied the hurricane as it traversed the French Frigate Shoals The small low lying East Island suffered a direct hit and was completely destroyed sediment being scattered across coral reefs to the north The island had served as one of the major nesting locations for the endangered green sea turtles and critically endangered Hawaiian monk seals 29 An estimated 19 percent of 2018 s sea turtle nests on the island were lost but all adult females tending the nests left before the storm Approximately half of Hawaii s green sea turtles nested on the island and Charles Littnan director of the National Oceanic and Atmospheric Administration s protected species division stated it would take years for the implications of the island s loss to be fully understood 30 By August 2019 satellite imagery showed that sand was beginning to reaccumulate on East Island 31 Coral reefs near the French Frigate Shoals Lisianski Island and the Pearl and Hermes Atoll were substantially damaged displacing the native fish population 1 Swells from Hurricane Walaka brought high surf to the main Hawaiian Islands on October 4 Walaka produced a surf that was 6 12 ft 1 8 3 7 m high along the southern and western shores of Niihau Kauai and Oahu The southern shores of Molokai Lanai and Maui experienced waves approximately 5 8 ft 1 5 2 4 m in height Hawaii s Big Island endured a surf that was 6 10 ft 1 8 3 0 m high on its western shores 32 At least 81 people had to be rescued by lifeguards off the southern shore of Oahu 33 See also edit nbsp Tropical cyclones portal Timeline of the 2018 Pacific hurricane season Weather of 2018 Tropical cyclones in 2018 List of Category 5 Pacific hurricanes Hurricane Iniki 1992 took a 90 northward turn under the influence of an upper level trough Hurricane Neki 2009 Category 3 hurricane affected the Papahanaumokuakea Marine National Monument as a tropical stormReferences edit a b c d e f g h i j k l m n o p q r s t u Houston Sam Birchard Thomas June 9 2020 Tropical Cyclone Report Hurricane Walaka PDF Report Central Pacific Hurricane Center Archived PDF from the original on June 12 2020 Retrieved September 4 2020 National Hurricane Center Hurricane Research Division Central Pacific Hurricane Center April 4 2023 The Northeast and North Central Pacific hurricane database 1949 2022 United States National Oceanic and Atmospheric Administration s National Weather Service A guide on how to read the database is available here nbsp This article incorporates text from this source which is in the public domain Zelinsky David September 22 2018 Tropical Weather Outlook Eastern Pacific 500 PM PDT Mon Sep 22 2018 Report NHC Graphical Outlook Archive National Hurricane Center Archived from the original on September 28 2018 Retrieved August 30 2020 Zelinsky David September 24 2018 Tropical Weather Outlook Eastern Pacific 500 PM PDT Mon Sep 24 2018 Report NHC Graphical Outlook Archive National Hurricane Center Archived from the original on September 30 2018 Retrieved August 31 2020 a b Wroe Derek September 29 2018 Tropical Storm Walaka Discussion Number 1 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 6 2020 Wroe Derek September 30 2018 Tropical Storm Walaka Discussion Number 2 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 7 2020 Jelsema Jon September 30 2018 Tropical Storm Walaka Discussion Number 3 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 7 2020 Powell Jeff September 30 2018 Tropical Storm Walaka Discussion Number 5 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 7 2020 Powell Jeff October 1 2018 Hurricane Walaka Discussion Number 6 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 7 2020 Jelsema Jon October 1 2018 Hurricane Walaka Discussion Number 8 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 7 2020 Kodama Kevin October 1 2018 Hurricane Walaka Discussion Number 9 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 8 2020 Kodama Kevin October 2 2018 Hurricane Walaka Discussion Number 10 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 8 2020 a b Jelsema Jon October 2 2018 Hurricane Walaka Discussion Number 12 Report Central Pacific Hurricane Center Archived from the original on July 29 2019 Retrieved September 8 2020 Brenchley Chris October 2 2018 Hurricane Walaka Discussion Number 13 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 8 2020 Ballard Robert October 3 2018 Hurricane Walaka Discussion Number 14 Corrected Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 8 2020 Ballard Robert October 3 2018 Hurricane Walaka Advisory Number 14 Report Central Pacific Hurricane Center Archived from the original on October 28 2020 Retrieved October 26 2020 Houston Sam October 3 2018 Hurricane Walaka Discussion Number 16 Corrected Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Brenchley Chris October 3 2018 Hurricane Walaka Discussion Number 17 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Brenchley Chris October 4 2018 Hurricane Walaka Discussion Number 18 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Houston Sam October 4 2018 Hurricane Walaka Discussion Number 20 Report Central Pacific Hurricane Center Archived from the original on July 29 2019 Retrieved September 9 2020 Wroe Derek October 5 2018 Hurricane Walaka Discussion Number 22 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Jelsema Jon October 5 2018 Tropical Storm Walaka Discussion Number 23 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Powell Jeff October 5 2018 Tropical Storm Walaka Discussion Number 25 Report Central Pacific Hurricane Center Archived from the original on September 9 2020 Retrieved September 9 2020 Houston Sam October 6 2018 Post Tropical Cyclone Walaka Discussion Number 28 Report Central Pacific Hurricane Center Archived from the original on July 29 2019 Retrieved September 9 2020 Matthew Cappucci October 2 2018 Two monster tropical cyclones are raging in the Pacific Ocean The Washington Post Archived from the original on December 24 2018 Retrieved October 14 2018 Magee David October 2 2018 Hurricane Walaka Threatens Seabirds With Direct Hit on Johnston Atoll in Pacific Newsweek Archived from the original on October 8 2018 Retrieved October 8 2018 Coast Guard evacuates Fish and Wildlife crew off Johnston Atoll ahead of Hurricane Walaka Coast Guard News October 2 2018 Archived from the original on October 9 2018 Retrieved October 8 2018 7 Researchers Evacuated From Pacific Atoll as Storm Nears The New York Times Associated Press October 3 2018 Archived from the original on October 12 2018 Retrieved October 12 2018 Milman Oliver October 24 2018 Hawaiian island erased by powerful hurricane The loss is a huge blow The Guardian Archived from the original on October 24 2018 Retrieved October 24 2018 D Angelo Chris October 23 2018 Remote Hawaiian Island Wiped Off The Map Huffington Post Archived from the original on October 23 2018 Retrieved October 23 2018 Eagle Nathan August 15 2019 NOAA The Reefs Weren t Damaged They Were Just Gone Honolulu Civil Beat Archived from the original on November 7 2020 Retrieved October 26 2020 Event High Surf in Kohala Hawaii 2018 10 04 06 00 HST 10 Report Storm Events Database National Centers for Environmental Information Archived from the original on November 20 2021 Retrieved October 26 2020 Gonzales Melody October 4 2018 Lifeguards rescue dozens as Walaka kicks up surf on Oahu s south shore KITV 4 Island News ABC Archived from the original on October 29 2020 Retrieved October 26 2020 External links edit nbsp Wikimedia Commons has media related to Hurricane Walaka Listen to this article 12 minutes source source nbsp This audio file was created from a revision of this article dated 15 October 2023 2023 10 15 and does not reflect subsequent edits Audio help More spoken articles The Central Pacific Hurricane Center s advisory archive on Hurricane Walaka nbsp This article incorporates public domain material from websites or documents of the National Weather Service Retrieved from https en wikipedia org w index php title Hurricane Walaka amp oldid 1218692216, wikipedia, wiki, book, books, library,

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