Typhoon Rammasun, known in the Philippines as Typhoon Glenda, was a powerful typhoon that was one of the only four Category 5 super typhoons on record in the South China Sea, with the other ones being Pamela in 1954, Rai in 2021 and Yagi in 2024. Rammasun had destructive impacts across the Philippines, South China, and Vietnam in mid July 2014. It was the strongest typhoon to hit the Chinese province of Hainan since Damrey in 2005. After Lingling and Kajiki earlier in 2014, Rammasun became the third tropical cyclone, and first typhoon to directly impact the Philippines in 2014. The ninth named storm and the third typhoon of the annual typhoon season, Rammasun formed in the Intertropical Convergence Zone, an area near the equator where the northeast and southeast trade winds come together, and slowly drifted northwest.
Having passed through the islands of Micronesia, the system turned west and quickly moved under the influence of a subtropical ridge (STR). Rammasun posed a significant threat to Luzon, as it was expected to reach typhoon intensity before making landfall there. Though initially forecast to make landfall in Cagayan Valley, the storm followed a more westerly path and was later forecast to make landfall in Rapu-Rapu, Albay in Bicol Region and then pass through Bataan and Zambales before brushing past Metro Manila.
In preparation for the storm, Governor of Guam Eddie Calvo declared the island in Condition of Readiness 3 and later upgraded it to Condition of Readiness 1. On July 11, NASA satellites revealed Rammasun passing directly over Guam. The American National Weather Service stated that an unexpected rise in wind shear kept the system from intensifying much further before reaching Guam. Rammasun only made landfall on Guam as a tropical depression, with winds much weaker than earlier anticipated. However, under the system, the island received a substantial amount of rainfall, making that day the wettest in around 3 months. The United States territory received of rain. Along with the Philippines, Taiwan also expected impact from Rammasun. Moderate to heavy rainfall was predicted through most of the country. Chinese meteorologists were focusing on second and/or third landfalls in the Chinese Hainan province and northern Vietnam. Residents of Hong Kong were also warned of rainfall and subsequent landslides.
Following the closure of maritime seaports, more than 100 passengers were reportedly stranded at the Port of Batangas, along with 39 rolling cargoes. Meanwhile, at least 841 passengers were stranded in five ports in the Bicol region, namely Matnog, Tabaco, Bulan, Cataingan and Pilar. A total 50 flights were cancelled and over 100 thousand families were evacuated as the typhoon neared landfall. The Philippine Department of Health said that they have prepared all government hospitals to aid the rescue and relief process during and after the typhoon. They claimed that they are much better prepared now, than they were for earlier typhoons. Ahead of the landfall, a city in the province of Albay had declared a state of calamity. At around 17:00 Philippine Standard Time (09:00 UTC), Rammasun's eye passed directly over Rapu-Rapu, Albay while the storm was at its initial peak intensity. Various parts of the National Capital Region reported power outages during the storm. They were reportedly caused by "a temporary system balance at 1:29 a.m. due to a sudden plant outage." Laguna was badly hit by the typhoon. At least 6,000 people were stranded at various seaports throughout the country due to the storm.
Meteorological history
On July 9, the United States Joint Typhoon Warning Center (JTWC) started to monitor a tropical disturbance, that had developed to the east of the Micronesian State of Chuuk. At this time the system had a broad and ill-defined circulation center which was associated with flaring and disorganized atmospheric convection. Over the next day the system gradually consolidated within an area of favorable conditions, with convection wrapping around the systems obscured low level circulation center. The system was subsequently declared a tropical depression during the next day, by both the Japan Meteorological Agency (JMA) and the JTWC with the latter assigning it the designation 09W.
Early on July 11, the JTWC reported that the system had intensified into a tropical storm, after they had assessed the intensity slightly higher than the Dvorak estimates from various agencies. Later that day as the system approached Guam, the JTWC reported that the system had not intensified into a tropical storm and downgraded it to a tropical depression. This was because of the lack of supporting Dvorak estimates from various agencies and various observations from Guam, that showed the system was a poorly defined low level circulation center with deep convection sheared to the northwest of the center. Early on July 12, the JMA reported that the depression had become a tropical storm and named it Rammasun, as the system passed through the Rota Channel to the north of Guam. Later that day as Rammasun moved westwards under the influence of the subtropical ridge of high pressure, the JTWC reported that it had regained tropical storm status after Dvorak estimates from various agencies supported it and the low level structure of the system had improved.
Rammasun entered the Philippine area of responsibility and was given a local name, Glenda on July 13. The storm maintained intensity while a burst of deep central convection developed and the LLCC became slightly more well defined. Over the next couple of hours, vertical wind shear decreased gradually. Rammasun tracked in a westerly direction along the periphery of the steering subtropical ridge. Outflow improved along the southwestern quadrant and Rammasun became a typhoon. The LLCC consolidated while convective banding became well defined and tightly wrapped. During July 14, both the JTWC and the JMA upgraded Rammassun to a typhoon after Dvorak estimates from various agencies suggested maximum sustained winds of .
Shortly before its Philippine landfall, Rammasun developed a wide eye. The storm had vigorous equatorward and westward outflow. At that time, the storm was peaking at 1-minute sustained winds and 10-minute sustained winds. Though initially expect to maintain that intensity and make landfall before weakening into a tropical storm again due to land interaction, Rammasun further intensified. Some six hours later, the JTWC spotted a eye, twice as wide as previously reported. The 1-minute sustained winds were set at , equivalent to Category 3 of the Saffir-Simpson Hurricane Wind Scale (SSHWS). Rammasun continued to strengthen, despite land interaction. Post landfall, the storm's windspeed continued to rise, as it was located in a very favorable environment. JTWC initially reported winds of 1-minute sustained winds before correcting it to in their best track, making it a Category 4-equivalent typhoon. By 00:00 UTC on July 16, Rammasun's eye had re-emerged into the South China Sea. The typhoon lost its eye feature due to its interaction with Philippines' rugged terrain. The convective structure had slightly degraded. However, convective banding remained tightly wrapped around the LLCC.
On July 18, Rammasun entered another area of very warm sea-surface temperatures. Consequently, Rammasun rapidly deepened and was upgraded to a Category 4 super typhoon by the JTWC, which was upgraded to Category 5 in post-season reanalysis. Later that day, Rammasun made landfall over Hainan at peak intensity, making it one of only two typhoons to make landfall at Category 5-equivalent intensity in China. During landfall, a station on Qizhou Island recorded a sea level pressure of 899.2 millibars, the lowest sea level pressure recorded in China and one of the lowest recorded sea level pressures in the world. The next day, the storm started to weaken. Later that day, both agencies downgraded Rammasun to a tropical storm as it moved to the province of Guangxi and made its third landfall. The JTWC made its final warning on the system in the night of the same day. Early on July 20, the JMA reported that Rammasun had weakened into a tropical depression before it was last noted later that day over the Chinese Province of Yunnan.
Preparations and impact
Mariana Islands On July 10, as the JTWC initiated advisories on the system, the United States National Weather Service Weather Forecast Office in Tiyan, Guam (NWS Guam) issued a tropical storm watch for Guam, Rota, Tinian, Saipan and surrounding waters out to . Later that day the Governor of Guam Eddie Calvo, declared the island nation to be in Tropical Cyclone Condition of Readiness 3 (TCCOR 3), as the strongest winds over the island were expected to peak between . Both of these warnings meant that destructive tropical storm force winds were possible on the islands during the next 48 hours. After the system was declared a tropical storm, tropical storm warnings were issued for Guam and Rota, while TCCOR 2 was declared for Guam. After TCCOR 2 was declared, all of the non essential agencies of the Guam Government and several business were shut down, including the Judiciary and University. Six elementary schools around the island were used as storm shelters, while woman who had been pregnant for more than 38 weeks and or high risk were asked to report to the Guam Memorial Hospital. A TCCOR 1 was subsequently declared during July 11, as destructive winds were expected to impact the island nation within twelve hours. As a result, all outdoor activity was prohibited until early the next day when the watches and warnings were cancelled after the system was downgraded to a tropical depression. Eddie Calvo subsequently reverted the TCCOR for Guam to the seasonal TCCOR, as no damaging or destructive winds were expected to affect Guam as the depression moved through the Rota Channel. NWS Guam subsequently noted that heavy thunderstorms had developed near the center of the system as it moved through the Rota Channel and that the weather over Guam could have been a lot worse.
Philippines
Rammasun (known as "Glenda" in the Philippines) was the first typhoon to impact the Philippines in over eight months, the previous being Typhoon Haiyan. Preparations for Rammasun started in the island nation, early on July 14. In the wake of the storm, The National Transmission Corporation of the country said in their statement, "Preparations included ensuring the reliability of communications equipment, availability of hardware materials and supplies necessary for the repair of damages to facilities, as well as the positioning of line crews in strategic areas, to facilitate immediate restoration work." Storm warning signal number 3 was hoisted over Catanduanes, while signal number 2 was raised over areas such as Camarines Norte, Burias Island, Ticao Island, Marinduque, and southern Quezon. Several islands in southern Luzon and eastern western, and central Visayas were put under storm signal number 1. Over 12 million people, in all, were asked to brace for the typhoon. Classes on all levels were reportedly suspended for the next two days. Philippine National Disaster Risk Reduction and Management Council's head Alexander Pama, in an interview, said "We are already warning the public to be on alert for possible effects of the weather disturbance: landslides, flash floods, strong rains and winds." more than 1,300 villages were advised about floods or landslides. The Embassy of the United States in Manila cancelled non-immigrant visa applicant interviews scheduled for July 15 and 16. All applicants were asked to reschedule their interviews.