Typhoon Irma, known in the Philippines as Typhoon Daling, affected the Philippines in late June1985. Typhoon Irma originated from a monsoon trough situated near Guam in the Western Pacific Ocean. It slowly developed, with insufficient organization delaying classification as a tropical cyclone. By June24, organization improved as the system encountered favorable conditions aloft and the disturbance attained tropical storm intensity the next day. Moving west, Irma gradually deepened, and on June28, it was believed to have attained typhoon intensity. On the morning of June27, Irma was upgraded into a typhoon. After passing northeast of the Philippines, Typhoon Irma attained its peak intensity on June29. Accelerating to the north and then the northeast, Irma steadily weakened as it encountered significantly less favorable conditions. The typhoon made landfall in central Japan on June30. Irma weakened below typhoon intensity the next day, and later on July1, Irma transition into an extratropical cyclone. The remnants of the cyclone were tracked until July7, when it merged with an extratropical low south of the Kamchatka Peninsula.
Although Irma stayed offshore the Philippines, moisture associated with the storm inundated areas already affected by Typhoon Hal earlier in the week. The capital city of Manila was 60% flooded, resulting in the evacuation of 40,000. Six drownings were reported in the nearby suburb of Quezon City, where 1,000families were evacuated. Citywide, eight people were killed. In Olongapo City, seven people were buried because of a landslide. Overall, more than 500,000people were directly affected by the typhoon throughout the country. A total of 253homes were destroyed, with 1,854others partially damaged. Nationwide, 65people were killed due to the typhoon and damage totaled $16million (1985USD).
Across Japan, Irma brought widespread flooded that resulted in 1,475mudslides, which damaged 625residencies. The storm left 650,000customers without power. In the Chiba Prefecture, seven people were injured. In the capital city of Tokyo, 119trees were toppled, 40homes were flooded, 20flights were cancelled, 26railway lines were suspended, and 25roads were flooded, all combining to leave more than 240,000stranded. In Izu Ōshima, 17 boats were swept away and 20houses were damaged. Nationwide, 19people were killed and 49others were injured. A total of 811dwellings were destroyed and 10,000others were damage. Throughout the country, the storm inflicted $545million in damage.
Meteorological history
During mid-June1985, the monsoon trough in the Western Pacific retreated eastward to near Guam, spawning several areas of low pressure. At 00:00UTC on June17, a tropical disturbance embedded within the monsoon trough was detected by meteorologists on weather satellite imagery about 400km (250mi) southwest of the island of Ponape. Although the disturbance's surface circulation was initially ill-defined, interaction with an upper-level low (ULL) to the southeast of Guam associated with a broader tropical upper-tropospheric trough (TUTT) enhanced development and thus the low was slow to develop. Moving west-northwest south of a ridge, the disturbance passed 180km (110mi) south-southeast of the Truk Atoll early on June18. Following an increase of thunderstorm activity associated with the disturbance in both coverage and organization, the JTWC issued a Tropical Cyclone Formation Alert (TCFA) for the system at noon the same day.[1]
During the next three days, the disturbance maintained vigorous, but poorly organized convection. Data from a Hurricane Hunter aircraft on June19 failed to locate a surface circulation. That afternoon, the TCFA was re-issued. On the afternoon of June20, the Hurricane Hunters finally founded a closed circulation, but outflow from nearby Typhoon Hal inhibited further development. Early on June22, the TCFA was cancelled because of a decrease in thunderstorm activity. By June24, however, vertical wind shear had begun to relax, coinciding with an expansion of the storm's southwesterly outflow channel.[1] Several hours later, the Japan Meteorological Agency (JMA) started tracking the cyclone.[2][nb 1] After an increase in thunderstorm activity, the TCFA was re-issued for the fifth and final time on the evening of June24. Based on a rapid improvement in the system's convective structure and Dvorak classifications of tropical storm intensity, the JTWC upgraded the system to Tropical storm Irma early on June25.[1] Shortly thereafter, a Hurricane Hunter aircraft measured winds of 80km/h (50mph) and a minimum barometric pressure of 994mbar (29.4inHg), though these winds were displaced roughly 150km (95mi) to the west of the center.[1] Based on this, the JMA followed suit and declared the system a tropical cyclone at 06:00UTC on June25.[2] At around the same time, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) started to follow the storm and assigned it with the local nameDaling.[4] At midday on June25, the JMA upgraded Irma to severe tropical storm intensity[2]
Initially, the JTWC predicted Irma to follow Hal along the monsoon trough into the South China Sea before curving around a subtropical ridge.[1] Irma slowly deepened, and according to the JMA, the system attained a secondary peak intensity of 115km/h (70mph) late on June 25.[2][nb 2] However, by June26, the JTWC revised its forecast and instead expected the storm to take a more northerly trek. On June27, Irma's forward speed slowed as it approached the edge of the subtropical ridge situated along the 130th meridian east[1] while intensifying.[2] That morning, both the JTWC and the JMA estimated that Irma attained typhoon intensity;[6] this upgraded was primarily based on data from ship reports.[1] Continuing to intensify, Irma moved northward.[6] However, by June28, the JMA indicated that Irma leveled off in intensity.[2] At 00:00UTC on June29, the JTWC estimated a peak intensity of 170km/h (105mph).[7] Six hours later, the JMA increased the intensity of the typhoon to 145km/h (90mph), its maximum intensity. At this time, the agency also assessed the pressure of the storm at 960mbar (28inHg).[2]
Shortly after its peak, Typhoon Irma began to accelerate towards the northeast in the direction of central Japan in response to westerlies.[1] Irma quickly weakened, and on the evening of June29, the JMA decreased the intensity of Irma to 120km/h (75mph).[2] Tracking just east of the Ryukyu Islands,[8] Irma began to acquire extratropical characteristics[1] A Hurricane Hunter flight on June30 suggested that that typhoon was encountering cooler and drier air, although the storm maintained a 55km (35mi)eye. That evening, the typhoon made landfall on Honshu.[1] At 00:00UTC on July1, the JMA downgraded Irma into a severe tropical storm.[2] Six hours later, the cyclone completed its extratropical transition[1] near Tokyo;[8] the JTWC issued its final warning on the system.[1] The JMA continued the monitor the system as it passed northeast of the Kuril Islands. On July7, the JMA ceased tracking the system as it had merged with an extratropical low south of the Kamchatka Peninsula.[2]
Preparations and impact
Prior to the arrival of Irma, storm signals were issued for much of Luzon, including Samar and Catanduanes.[9] Although the system remained offshore Taiwan,[1] it came close enough to require storm signals.[10]
Even though Typhoon Irma passed well east to the Philippines, over 30in (710mm) of rain fell over parts of Luzon. These rains resulted in major flooding; Irma was also the second storm to directly affect the nation within a week, following Typhoon Hal.[1] The capital city of Manila sustained flooding along low-lying areas, which stranded motorists.[11] A total of 60% of the city was flooded, forcing the evacuation of 40,000persons.[12] Six drownings occurred in the suburb of Quezon City, where 1,000families were evacuated, 700tochurches and 300toschools. Within the Manila metropolitan area, a man and a woman were also electrocuted. All classes in Manila were suspended, and many stores and offices shut down for a day. Furthermore, domestic flights in and out of Manila were canceled since the runway was flooded with water 600mm (25in) deep. Citywide, eight people were killed. According to press reports, Irma was to worst tropical cyclone to directly impact Manila in over 10years.[13]
Offshore Bataan, eight fishermen were initially rendered missing after a boat capsized.[13] In Olongapo City, seven people were buried due to a landslide.[12] In the downtown Santa Cruz area, all forms of transportation except for the railroad were immobile.[13] The Makati area sustained waist-deep flooding. Due to both Irma and Hal, 14communities in Tarlac were flooded, leaving 375,000people displaced,[14] 116,963of whom were evacuated to 46 evacuation centers. Seven bridges were also damaged.[15] Overall, 511,067people, or 94,661families were directly affected by the typhoon. A total of 253homes were destroyed, with 1,854others partially damaged.[16] Nationwide, 65people were killed due to the typhoon. The storm inflicted $13.7million in damage to infrastructure and $2.3million in damage to agriculture, totaling to approximately $16million.[17][nb 3]
Upon making landfall on Honshu,[1] Irma became the first tropical system to strike the nation that season. Impacting an area already devastated by prior flooding,[18] Irma deluged the archipelago with additional precipitation.[19]Mount Ontake received 718mm (30in) of rain throughout the duration of the storm.[20] Additionally, Mount Amagi recorded 18.0in (457mm) in a day, including 64mm (2.5in) in an hour,[21] both storm highs in those respective categories.[19] A total of 1,475mudslides occurred in Japan, resulting in 625damaged homes.[15] Approximately 650,000customers were left without power at the height of the storm[22] while 160trains were delayed or cancelled, which left 50,000people stranded. In Chiba Prefecture, one person was listed missing due to a drowning,[18] where seven persons were also hurt and over 200houses were flooded.[23] There, 400,000individuals were also stranded due to lack of train service.[22][24] In Tokyo, 119trees were toppled and 25roads were flooded.[18] Twenty domestic airline flights were cancelled and 26railway lines within Tokyo were suspended,[23] leaving 240,000people stranded.[22] Throughout the city, at least 40dwellings sustained flooding.[23] In Izu Ōshima, 17boats were swept away and 20houses were damaged. Offshore, 26individuals were rescued from a 5,100 tonnes (5,100,000kg) freighter Gloria Fortuna.[18] Throughout the country, 493people sought refuge in shelters.[25] In all, 19people were killed[26] and 49others were injured. A total of 811dwellings were destroyed[19] and 10,000homes were damaged,[26] with 12,691houses flooded. Nationwide, a total of 31,617ha (78,125 acres) of crops were damaged.[19] Across Japan, damage amounted to $545million,[19][nb 4] including at least $61million in property damage.[8]
Wind estimates from the JMA and most other basins throughout the world are sustained over 10minutes, while estimates from the United States-based Joint Typhoon Warning Center are sustained over 1minute. 10minute winds are about 1.14 times the amount of 1minute winds.[5]
Joint Typhoon Warning Center; Naval Pacific Meteorology and Oceanography Center (1986). Annual Tropical Cyclone Report: 1985(PDF) (Report). United States Navy, United States Air Force. Retrieved August 11, 2016.
Christopher W Landsea; Hurricane Research Division (April 26, 2004). "Subject: D4) What does "maximum sustained wind" mean? How does it relate to gusts in tropical cyclones?". Frequently Asked Questions. National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Retrieved August 11, 2016.
Kenneth R. Knapp; Michael C. Kruk; David H. Levinson; Howard J. Diamond; Charles J. Neumann (2010). 1985 IRMA (1985168N05156). The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data (Report). Bulletin of the American Meteorological Society. Retrieved August 11, 2016.
Destructive Typhoons 1970-2003 (Report). National Disaster Coordinating Council. November 9, 2004. Archived from the original on November 9, 2004. Retrieved May 1, 2017.
Digital Typhoon (March 19, 2013). Typhoon 198506 (IRMA). Digital Typhoon Detailed Track Information (Report). National Institute of Informatics. Retrieved May 2, 2017.
Digital Typhoon (March 19, 2013). AMeDAS ONTAKESAN (48601) @ Typhoon 198506. Digital Typhoon Detailed Track Information (Report). National Institute of Informatics. Retrieved May 2, 2017.
Digital Typhoon (March 19, 2013). AMeDAS AMAGIASAN (50427) @ Typhoon 198506. Digital Typhoon Detailed Track Information (Report). National Institute of Informatics. Retrieved May 2, 2017.
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