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Tropical cyclones |
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Outline of tropical cyclones Tropical cyclonesportal |
Tropical cyclone warnings and watches are alerts 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 preparation for the cyclone, including evacuation of vulnerable areas where necessary. It is important that interests throughout the area of an alert make preparations to protect life and property, and do not disregard it on the strength of the detailed forecast track.
Hurricane warning levels |
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Hurricane warning |
Hurricane conditions expected within 36 hours. |
Hurricane watch |
Hurricane conditions possible within 48 hours. |
Tropical storm warning |
Tropical storm conditions expected within 36 hours. |
Tropical storm watch |
Tropical storm conditions possible within 48 hours. |
Storm surge warning |
Life-threatening storm surge possible within 36 hours. |
Storm surge watch |
Life-threatening storm surge possible within 48 hours. |
Extreme wind warning |
Winds reaching Category 3 status or higher likely (issued two hours or less before onset of extreme winds). |
New tropical cyclone position and forecast information is available at least every twelve hours in the Southern Hemisphere and at least every six hours in the Northern Hemisphere from Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers. [1] [2] [3] [4] [5] In conjunction with the National Hurricane Center, the national meteorological and hydrological services of Central America, the northern Atlantic Ocean, and the northeastern Pacific Ocean east of the 140th meridian west, excluding mainland Africa and Europe, all issue tropical storm/hurricane watches and warnings. [6] Tropical storm watches are issued when gale and storm force winds of between 34 and 63 knots (39–73 mph; 63–118 km/h) are possible, within 48 hours in a specified area in association with a tropical, subtropical or post-tropical cyclone. [7] These watches are upgraded to tropical storm warnings, when gale and storm force winds become expected to occur somewhere in the warning area within 36 hours. [7] Hurricane watches are issued when sustained winds of 64 knots (74 mph; 119 km/h) are possible, within 48 hours in a specified area in association with a tropical, subtropical or post-tropical cyclone. [7] These watches are upgraded to hurricane warnings, when hurricane-force winds become expected to occur somewhere in the warning area within 36 hours. [7]
Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch and warnings are issued in advance of the anticipated onset of tropical-storm-force winds, rather than in advance of the anticipated onset of hurricane-force winds. [7] At times a tropical storm warning and a hurricane watch can both be in effect due to uncertainties in the forecast. These watches and warnings are also issued by the Central Pacific Hurricane Center for the Hawaiian Islands and the Weather Forecast Office in Guam for parts of Micronesia but not for American Samoa due to an international agreement. [8]
Within the United States an extreme wind warning is issued by the National Weather Service for any land areas that are expected to be impacted by a major (Category 3 or higher) hurricane and by sustained surface winds greater than or equal to 100 knots (115 mph; 185 km/h). [8] The warning is issued just prior to when the strongest winds of the eyewall are expected to impact an area. [9] The warning is to be issued for the smallest area possible, and be valid for times of two hours or less. [9] It was developed in response to confusion resulting from the landfall of Hurricane Katrina. NWS offices in Jackson and New Orleans/Baton Rouge issued 11 tornado warnings for areas that would not experience an actual tornado, but would experience extreme wind speeds commonly associated with tornadoes. [10] The extreme wind warning is now expected to be used in these situations.
In 2017, the National Hurricane Center introduced a new system of warnings and watches for storm surge, which would cover the Atlantic and Gulf Coasts of the United States. A storm surge watch would be issued when a life-threatening storm surge, associated with a potential or ongoing tropical, subtropical or post-tropical cyclone, is possible within the next 48 hours. These watches would be upgraded to storm surge warnings when there is a danger of life-threatening storm surge occurring within 36 hours. However, both watches and warnings may be issued earlier than specified if environmental conditions are expected to hamper preparations. [11]
In Mexico, a color coded alert system is used to keep the public informed when a tropical cyclone or possible tropical cyclones poses a threat to the nation. The scale starts with blue at the bottom being minimal danger, then proceeds to a green alert, which means low level danger. A yellow alert signifies moderate danger, followed by an orange alert that means high danger level. The scale tops off with a red alert, the maximum level of danger. [12]
In Canada, terminology is fairly similar to that of the United States, but there are a few differences: [13]
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A two-stage warning system was long-established in China for tropical cyclones of tropical storm intensity of above. [14] Nowadays, the use of this system is restricted to coastal waters only. Thus, warnings may be discontinued even if a cyclone is maintaining tropical storm intensity inland. Color-coded alerts (below) may be in effect independently of any two-stage warnings.
Later, China Meteorological Administration standardized the system for national use. [15] This set is part of a larger warning system that covers other forms of severe weather conditions, such as extreme temperature, torrential rainfall, drought, etc.
Guangdong continued to set up the White typhoon alert for typhoon, indicating that tropical cyclones may affect the area within 48 hours. In some inland areas that are less affected by tropical cyclones (such as Qinghai, etc.), there is no typhoon warning signal, but when it is hit by tropical cyclones, a strong wind warning signal will be issued. The winds represented by each color are consistent with the typhoon warning signal.
Typhoon warning signals used in Guangzhou from June 1, 1995, to November 1, 2000: [16]
Name | Meaning |
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Windproof Info (Tropical Storm or Typhoon Info) | indicates that a tropical storm or typhoon has entered the South China Sea (or has formed in the South China Sea) and is likely to move to the coastal areas of the province. |
Windproof Warning (Tropical Storm and Typhoon Warning) | Indicating that a tropical storm or typhoon warning enters the South China Sea, its route is moving in the direction of the Pearl River Estuary. If there is no change, it may land within 48 hours. |
Windproof Special Alert (Tropical Storm or Typhoon Emergency Alert) | Indicating that a tropical storm or typhoon hits the Pearl River Estuary within 24 hours, or landed in a coastal area within 150 kilometers of the Pearl River Estuary, which will have a serious impact on Guangzhou. |
Disarming (Tropical Storm or Typhoon Disarming Alert) | indicates that a tropical storm or typhoon has landed (or weakened to a low pressure). |
Typhoon warning signals used from November 1, 2000, to May 2006: [17]
Name | Signal | Meaning |
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White typhoon alert | Tropical cyclones may affect the area within 48 hours. | |
Green typhoon alert | Tropical cyclones will be within 24 hours or are affecting the area, with an average wind level of strong winds (6-7) (41-62 km/h). | |
Yellow typhoon alert | Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of strong gale (8-9) (63-87 km/h). | |
Red typhoon alert | Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of strong storm (10-11) (88-117 km/h). | |
Black typhoon alert | Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of typhoon (>12). |
Typhoon warning signals used from June 1, 2006, to December 31, 2014: [18]
Typhoon warning signals used since January 1, 2015: [19]
Shenzhen currently uses a different signal from Guangdong Province: [18] [20]
Zhuhai adopts the signal style of Guangdong Province, but the meaning of the signal is different: [21]
Shenzhen and Zhuhai used digitally arranged typhoon signals from June 4, 1994, to November 1, 2000, [22] but they have now been replaced by typhoon warning signals.
The coastal ports of various cities in mainland China will still hang the squash signal when the typhoon hits. [23] The sign is roughly the same as the typhoon signal used in Shenzhen and Zhuhai. [24]
The Pearl River Delta uses a variety of warning systems to inform the public regarding the risks of tropical cyclones to the area.
The Hong Kong Observatory issues typhoon signals to indicate the existence and effects of a tropical cyclone on Hong Kong. The first numeric warning system was used in 1917.
The Macao Meteorological and Geophysical Bureau in Macau uses a similar system. [25]
In Hong Kong the typhoon signal system consists of 8 signals in 5 levels numbered non-consecutively for historical reasons. [26] [27] Each signal has a day signal and a night signal for hoisting, which are still hoisted in Macau but no longer hoisted in Hong Kong. Day signals are also used as signal symbols in both places.
The Japan Meteorological Agency (JMA) is the government agency responsible for gathering and providing results for the public in Japan, that are obtained from data based on daily scientific observation and research into natural phenomena in the fields of meteorology, hydrology, seismology and volcanology, among other related scientific fields. Its headquarters is located in Tokyo.
JMA is also designated one of the Regional Specialized Meteorological Centers (RSMC) of the World Meteorological Organization. It has the responsibility for weather forecasting, tropical cyclone naming and distribution of warnings for tropical cyclones in the Northwestern Pacific region.
Warning Signal | Meaning |
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TCWS #1 | winds of 39–61 km/h (21–33 kn; 24–38 mph) are prevailing or expected to occur within 36 hours |
TCWS #2 | winds of 62–88 km/h (33–48 kn; 39–55 mph) are prevailing or expected to occur within 24 hours |
TCWS #3 | winds of 89–117 km/h (48–63 kn; 55–73 mph) are prevailing or expected to occur within 18 hours |
TCWS #4 | winds of 118–184 km/h (64–99 kn; 73–114 mph) are prevailing or expected to occur within 12 hours |
TCWS #5 | winds of 185 km/h (100 kn; 115 mph) or greater are prevailing or expected to occur within 12 hours |
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) releases tropical cyclone warnings in the form of Tropical Cyclone Wind Signals (TCWS, or "wind signals"). [29] Within this warning system, an area having a wind signal may be under:
These wind signals are hoisted when an area (in the Philippines only) is about to be directly affected by tropical cyclone winds. Wind signals for specific areas can be escalated to higher signal levels (and the lead times shortened consequently) as a tropical cyclone gains strength and/or gets closer to the areas about to be affected. De-escalation and/or lifting of wind signals are implemented once a tropical cyclone weakens and/or gets farther away from the affected areas. The lead time is also only valid for the first issuance.
Vietnam recognises its typhoon season from the beginning of June through to the end of November, [30] with an average of four to six typhoons hitting the country annually. [31] Any tropical cyclones here are monitored by the National Center for Hydro-Meteorological Forecasting (NCHMF), which is the nation's official meteorological agency and was established in January 2003. The NCHMF tracks a storm should it enter the agency's monitoring area range which is within the East Sea to the west of 120°E and north of 5°N. Any storm that enters this area is assigned a number, and is set according to its sequence of its occurrence – as for instance with Bão số 1 etc., which translates to "Storm no. 1". Bão comes from "暴', meaning ferocious, violent or vicious, but in vernacular Vietnamese has come to mean "storm".
In 2014, the Vietnamese government issued Decree no.44/2014, introduced five warning levels, but NCHMF only use three out of five levels to issue typhoon warnings:
- "Disaster Risk Alert - Level 3" (High Alert), decorated with orange
- "Disaster Risk Alert - Level 4" (Very High Alert), decorated with red
- "Disaster Risk Alert - Level 5" (Disaster Alert), decorated with pink
The Australian Bureau of Meteorology will issue a cyclone watch for a specified part of Australia, when a tropical cyclone is expected to cause gale-force winds in excess of 62 km/h (40 mph) within 24–48 hours and subsequently make landfall. [32] A cyclone warning is subsequently issued for a specified part of Australia when a tropical cyclone, is expected to cause or is causing gale-force winds in excess of 62 km/h (40 mph) within 24 hours and is subsequently expected to make landfall. [32]
The Fiji Meteorological Service (FMS) issues a tropical cyclone alert for the Cook Islands, Fiji, Kiribati, Nauru, Niue, Tokelau and Tuvalu, when a tropical cyclone has a significant probability of causing gale-force winds or stronger winds within 24–48 hours. [33] Gale, storm and hurricane-force wind warnings are subsequently issued for the above areas by FMS, when a tropical cyclone is either causing or expected to cause either gale storm or hurricane-force winds within 24 hours. [33]
Météo-France is responsible for the issuance of tropical cyclone watches and warnings for New Caledonia, Wallis and Futuna, French Polynesia and the Pitcairn Islands. [33] The National Meteorological and Hydrological Services of the Solomon Islands, Samoa, Indonesia, Papua New Guinea, Tonga, New Zealand, Vanuatu, Timor Leste and American Samoa are responsible for their own watches and warnings. [33]
The Indian Meteorological Department (IMD/RSMC New Delhi) is responsible for tracking tropical cyclones within the North Indian Ocean. Météo-France in Réunion (MFR/RSMC La Reunion) is responsible for the issuing advisories and tracking of tropical cyclones in the southwest part of the basin, however, the naming of systems is deferred to the Mauritius and Madagascar weather services.
Cyclone warning levels |
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Cyclone watch |
Cyclonic storm conditions possible within 72 hours. |
Cyclone alert |
Cyclonic storm conditions possible within 48 hours. |
Cyclone warning |
Cyclonic storm conditions expected within 24 hours. |
Landfall outlook |
Cyclonic storm conditions expected within 12 hours. |
The IMD issues warnings in four stages for the Indian coast.
Cyclonic storm conditions mean what winds in excess of 63 km/h (39 mph) are possible. [34]
Mauritius Meteorological Services is responsible for naming tropical systems in the South-West Indian Ocean between 55°E and 90°E. They issue four different levels of cyclone warnings for the islands of Mauritius and Rodrigues.
Météo-France issues five levels of alerts for the French overseas department and region of Réunion. [36]
The United States Department of Defense uses a multi-stage system called the Hurricane Condition (HURCON) in the North Atlantic and the Northeast Pacific and the Tropical Cyclone Condition of Readiness (TCCOR) in the western Pacific to prepare bases and evacuate assets and personnel in advance of adverse weather associated with tropical cyclones. [37]
The alerts are recommended by weather facilities either on base or by central sites like the National Hurricane Center or the Joint Typhoon Warning Center and are generally related to the timing and potential for destructive sustained windspeeds of above 50 kn (58 mph; 93 km/h). [37] Recommendations are then considered by base or area commanders along with other subjective factors for setting the alert status like assets, holidays or the bases experience in emergency preparedness. [37] The bases prefer to set these alerts sequentially, from HURCON or TCCOR 5 with destructive winds expected within 96 hours, through levels 4, 3, 2 and if needed to a series of four different level 1 conditions, however depending on the cyclone's movement or location some of these signals can be skipped. [37] [38] After a system passes and stops affecting the base, the authorities can decide to revert to the lowest level or stay in a heightened approach if another tropical cyclone is approaching. [37]
A gale warning is an alert issued by national weather forecasting agencies around the world in an event that maritime locations currently or imminently experiencing winds of gale force on the Beaufort scale. Gale warnings allow mariners to take precautionary actions to ensure their safety at sea or to seek safe anchorage and ride out the storm on land. Though usually associated with deep low-pressure areas, winds strong enough to catalyze a gale warning can occur in other conditions too, including from anticyclones, or high-pressure systems, in the continental interior. The winds are not directly associated with a tropical cyclone.
The 2006 Pacific typhoon season was a near-average season which produced a total of 23 named storms, 15 typhoons, and six super typhoons. The season ran throughout 2006, though most tropical cyclones typically develop between May and October. The season's first named storm, Chanchu, developed on May 9, while the season's last named storm, Trami, dissipated on December 20.
Tropical cyclones are ranked on one of five tropical cyclone intensity scales, according to their maximum sustained winds and which tropical cyclone basins they are located in. Only a few scales of classifications are used officially by the meteorological agencies monitoring the tropical cyclones, but other scales also exist, such as accumulated cyclone energy, the Power Dissipation Index, the Integrated Kinetic Energy Index, and the Hurricane Severity Index.
The Philippines is a typhoon-prone country, with approximately 20 typhoons entering its area of responsibility each year. Locally known generally as bagyo, typhoons regularly form in the Philippine Sea and less regularly, in the South China Sea, with the months of June to September being the most active, August being the month with the most activity. Each year, at least ten typhoons are expected to hit the island nation, with five expected to be destructive and powerful. In 2013, Time declared the country as the "most exposed country in the world to tropical storms".
This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.
The 2008 Pacific typhoon season was a below average season which featured 22 named storms, eleven typhoons, and two super typhoons. The season had no official bounds; it ran year-round in 2008, but most tropical cyclones tend to form in the northwestern Pacific Ocean between May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
The 2007–08 South-West Indian Ocean cyclone season was the third most active tropical cyclone season, along with the 1985–86 season and behind the 1993–94 season and the 2018–19 season, with twelve named tropical cyclones developing in the region. It began on November 15, 2007, and ended on April 30, 2008, with the exception for Mauritius and the Seychelles, which ended May 15. These dates conventionally delimit the period of each year when most tropical cyclones form in the basin, which is west of 90°E and south of the Equator. Tropical cyclones in this basin are monitored by the Regional Specialised Meteorological Centre in Réunion.
The 2001–02 Australian region cyclone season was a slightly below average tropical cyclone season. It officially started on 1 November 2001, and ended on 30 April 2002. However, the formation of Tropical Cyclone Alex on 26 October 2001 marked an earlier beginning to the season, and the season extended past the official end of the season when Tropical Cyclone Upia formed on 25 May 2002. The regional tropical cyclone operational plan also defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2001 and ended on 30 June 2002. The scope of the Australian region is limited to all areas south of the equator, east of 90°E and west of 160°E. This area includes Australia, Papua New Guinea, western parts of the Solomon Islands, East Timor and southern parts of Indonesia.
The 2008–09 South-West Indian Ocean cyclone season was a slightly above average event in tropical cyclone formation. It began on November 15, 2008, and officially ended on April 30, 2009, with the exception for Mauritius and the Seychelles, for which it ended on May 15, 2009. These dates conventionally delimit the period of each year when most tropical cyclones form in the basin, which is west of 90°E and south of the Equator. Tropical cyclones in this basin were monitored by the Regional Specialised Meteorological Centre in Réunion.
The 2009 North Indian Ocean cyclone season was an event in the annual cycle of tropical cyclone formation. The North Indian Ocean cyclone season has no official bounds, but cyclones tend to form between April and December, with peaks in May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.
Typhoon Prapiroon, known in the Philippines as Tropical Storm Henry, was a minimal typhoon which caused deadly flooding in southern China in August 2006. Prapiroon developed out of a persistent area of convection accompanied by an area of low pressure on July 25 about 120 km (75 mi) west-southwest of Yap. Two days later, both the Japan Meteorological Agency (JMA) and PAGASA classified the system as a tropical depression, with PAGASA giving it the local name 'Henry'. By July 31, the Joint Typhoon Warning Center (JTWC) classified the system as Tropical Depression 07W. A strong subtropical ridge located to the north of the depression led to a west-northwest movement for most of the storm existence.
Tropical Cyclone Tam was the first named storm of the 2005–06 South Pacific cyclone season. Forming out of a tropical depression on January 6, the storm gradually intensified, becoming a tropical cyclone on January 12 and receiving the name Tam. Although it was traveling at a quick pace, the storm gained organization and reached its peak intensity with winds of 85 km/h (53 mph) the following day. However, the increasing forward motion of the storm, combined with strengthening wind shear, caused Tam to rapidly weaken on January 14. Around that time, it entered the Tropical Cyclone Warning Centre in Wellington, New Zealand's area of responsibility. Shortly thereafter, the storm transitioned into an extratropical cyclone and dissipated early the next day. Cyclone Tam produced heavy rainfall and strong winds over American Samoa upon being named. The precipitation caused several mudslides and flooding, which inflicted $26,000 in damage. The storm also had minor effects on Niue, Tonga, and Futuna.
Typhoon Mirinae, known in the Philippines as Typhoon Santi, was the 34th depression and the 14th typhoon in the 2009 Pacific typhoon season. It came several weeks after Typhoons Ketsana and Parma devastated the Philippines, thus adding additional damage wrought by the two preceding typhoons.
Severe Tropical Cyclone Gwenda is tied with Cyclone Inigo as the most intense Australian tropical cyclone on record, with a barometric pressure of 900 hPa (mbar) and was the most intense storm worldwide in 1999. Forming out of a tropical disturbance over the Arafura Sea on 2 April 1999, the precursor to Gwenda tracked slowly westward and gradually became more organised. On 4 April, the system developed into a Category 1 cyclone and was named Gwenda. It began to undergo explosive intensification the following day, and in a 30-hour span ending early on 7 April, the storm's maximum 10-minute sustained wind speed increased from 75 to 225 km/h and its barometric pressure decreased to 900 hPa (mbar). The Joint Typhoon Warning Center reported that the storm had peaked as a high-end Category 4 equivalent on the Saffir–Simpson hurricane scale.
Severe Tropical Cyclone Magda was a relatively small tropical cyclone that brought minor damage to parts of Western Australia in January 2010. The third named storm of the 2009–10 Australian region cyclone season, Magda originated from a tropical low near the Indonesian island of Roti on 18 January. Quickly strengthening, the system attained tropical cyclone status on 20 January and later reached severe tropical cyclone intensity on 21 January as it approached Western Australia. Late on 21 January, Magda made landfall in the Kimberley region with winds of 130 km/h (81 mph) before quickly weakening over land. The remnants of Magda persisted until 24 January, at which time they dissipated east of Port Hedland.
The following is a glossary of tropical cyclone terms.
Typhoon Kai-tak, known in the Philippines as Tropical Storm Helen, was a mild tropical cyclone that affected China, Vietnam and Laos. It was the seventh typhoon and the thirteenth named storm of the 2012 Pacific typhoon season. The storm killed 41 people and caused a sum of US$765 million in losses. Kai-tak can be tracked back to the broad area of disturbance embedded in a monsoonal trough that was first spotted, early on August 10. It was only at midnight, on August 16, when the JMA officially declared Kai-tak a typhoon. On the morning of August 17, the windspeed dropped to 60 knots and was no longer a typhoon. The typhoon caused heavy damage in China's two provinces killing four people and causing huge economic loss. Kai-Tak slammed the northern Philippines triggering flash floods and landslides and killing at least ten people, one week after deadly monsoon rains battered the country. In Vietnam, Kai-Tak has stormed across the country's north bringing high winds and floods to several areas including the capital Hanoi.
Typhoon Usagi, known in the Philippines as Typhoon Odette, was a violent tropical cyclone which affected Taiwan, the Philippines, China, and Hong Kong in September 2013. Usagi, or which means the constellation Lepus in Japanese, was the fourth typhoon and the nineteenth tropical storm in the basin. Developing into a tropical storm east of the Philippines late on September 16, Usagi began explosive intensification on September 19 and ultimately became a violent and large typhoon. Afterwards, the system weakened slowly, crossed the Bashi Channel on September 21, and made landfall over Guangdong, China on September 22.
Intense Tropical Cyclone Kenneth was the strongest tropical cyclone to make landfall in Mozambique since modern records began. The cyclone also caused significant damage in the Comoro Islands and Tanzania. The fourteenth tropical storm, record-breaking tenth tropical cyclone, and ninth intense tropical cyclone of the 2018–19 South-West Indian Ocean cyclone season, Kenneth formed from a vortex that the Météo-France office on La Réunion (MFR) first mentioned on 17 April. The MFR monitored the system over the next several days, before designating it as Tropical Disturbance 14 on 21 April. The disturbance was located in a favorable environment to the north of Madagascar, which allowed it to strengthen into a tropical depression and later a tropical storm, both on the next day. The storm then began a period of rapid intensification, ultimately peaking as an intense tropical cyclone with 10-minute sustained winds of 215 km/h (134 mph) and a minimum central pressure of 934 hPa. At that time, Kenneth began to undergo an eyewall replacement cycle and weakened slightly, before making landfall later that day as an intense tropical cyclone. As a result of land interaction, Kenneth became disorganised as it made landfall and rapidly degenerated thereafter. The storm then shifted southward, with the MFR cancelling all major warnings for inland cities. Kenneth was reclassified as an overland depression after landfall, with the MFR issuing its warning at midnight UTC on 26 April. Thunderstorm activity developed off the coast of Mozambique on 27 April as the system began drifting northward. Kenneth re-emerged off the coast of northern Mozambique on 28 April, before dissipating on the next day.
The Tropical Cyclone Wind Signals are tropical cyclone alert levels issued by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) to areas within the Philippines that may be affected by tropical cyclone winds and their associated hazards.