The 2004 Pacific typhoon season produced the second-highest accumulated cyclone energy value in the basin, only after 1997. Moreover, it was an extremely active season, featuring twenty-nine named storms, nineteen typhoons, and six super typhoons. The season's high activity was brought on due to the presence of a Modoki El Niño - a rare type of El Niño in which extremely favorable conditions exist in the Western Pacific basin due to the normally warmer-than-average waters shifting further westward. The season's first named storm and also the first typhoon, Sudal, developed on April 4, later was reached typhoon status two days later, and became the first super typhoon of the year three days later. The season's last named storm, Noru, dissipated on December 22.
The scope of this article is limited to the Pacific Ocean to the north of the equator between 100°E and 180th meridian. Within the northwestern Pacific Ocean, there are two separate agencies that assign names to tropical cyclones, which can often result in a cyclone having two names. The Japan Meteorological Agency (JMA) names a tropical cyclone should it be judged to have 10-minute sustained wind speeds of at least 65 km/h (40 mph) anywhere in the basin, whilst the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E and 115°E and between 5°N and 25°N, regardless of whether or not a tropical cyclone has already been given a name by the JMA. Tropical depressions that are monitored by the United States' Joint Typhoon Warning Center (JTWC) are given a number with a "W" suffix.
Seasonal summary
The activity of the season was extremely high, while the impacts of the typhoons were damaging and deadly, including four consecutive typhoons that struck them in the Philippines. In August, Typhoon Rananim struck Taiwan and China causing widespread damage, killing 169 people and with an estimated $2.44 billion (USD 2004) in damage. Typhoon Aere also caused heavy damage in China after Rananim killed 107 people there with minimal damage. Typhoon Songda was the costliest typhoon of the season to hit Japan, with damage estimated at $9.3 billion (US$2004) and 28 people killed. In October, Typhoon Tokage hit Japan as a tropical storm, causing a total of 95 deaths and damage estimated at $2.3 billion (2004 USD). Tropical Depression Winnie struck the Philippines killing a total of 1,593 people, making Winnie the deadliest storm of the season since Tropical Storm Thelma in 1991. After the month of November, the seasonal activity onwards decreased. The activity during the month included two typhoons. Muifa struck the Philippines after Winnie, killing 68 people and subsequently bringing heavy rains to Thailand killing 40 people. The fourth and last consecutive typhoon to hit the Philippines was Nanmadol which made landfall as a Category 4 typhoon in that country, killing a total of 77 people.
The Accumulated Cyclone Energy (ACE) index of this season amounted to 60% above the normal level for Pacific typhoon seasons, calculated by Colorado State University using data from the Joint Typhoon Warning Center to be 480.6 units. This makes the season the second-most intense Pacific typhoon season in recorded history, only after 1997. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 miles per hour (63 km/h).
Systems
Typhoon Sudal (Cosme)
On April 5, Tropical Depression 03W began its life between Chuuk and Pohnpei. As it drifted to the northwest, it strengthened into a tropical storm. Sudal turned to the west, and steadily intensified to become a typhoon on April 6. On the April 9, with maximum sustained winds of 115 kn/130 mph, Typhoon Sudal hit the island of Yap. After ravaging the island, Sudal reached a peak of 130 kn/150 mph winds. The typhoon turned to the northeast and became extratropical early on April 16.
Yap experienced catastrophic damage, with 90% of buildings destroyed, 1,500 left homeless, but fortunately no fatalities. Sudal is a Korean word meaning otter.
Typhoon Nida (Dindo)
A monsoon trough spawned Tropical Depression 04W east of the Philippines on May 13. The depression quickly strengthened, reaching tropical storm intensity on May 14 and typhoon status just six hours later. On May 15 and 16 while moving northwest towards the Philippine coast, Nida rapidly intensified to a 140 kn/160 mph super typhoon, and crossed the eastern Philippines shortly thereafter. Nida weakened slightly over the islands, and began to move to the north and northeast in response to a break in the subtropical ridge. It became extratropical on May 21 east of Japan, after causing 31 deaths and about $1.3 million in damage. Nida is a Thai female name.
In the Philippines, evacuation centers were opened to accommodate 2,986 people. The typhoon approach canceled ferry operations stranding 15,057 passengers. In Taiwan, forecasters at the Central Weather Bureau issued a typhoon warning as forecast models predicted a high probability of the typhoon hitting Taiwan.
Severe Tropical Storm Omais (Enteng)
A tropical disturbance southwest of Chuuk organized into a tropical depression on May 16, one of 3 active tropical cyclones in the Western Pacific at the time. The depression developed quickly, reaching tropical storm status later that day and reaching a peak of 60 kn/70 mph winds three days later on May 19. A weakening ridge brought Omais northward, where it became extratropical on May 22.
Operationally, Omais was classified as a typhoon, but in post-analysis, it was dropped to a severe tropical storm. Omais is a Palauan word meaning 'wandering around'.
Typhoon Conson (Frank)
In the South China Sea, a stationary area of disturbed weather developed into Tropical Depression 07W on June 4. It tracked eastward then northeastward, becoming a tropical storm on June 5 and a typhoon on June 7. Conson passed between Luzon and Taiwan, and peaked with 100 kn/115 mph winds on June 9. Conson weakened as it continued northeastward, and became extratropical on June 11 near Japan without causing any reported damage. Conson is an area in Vietnam containing many historical monuments.
Severe Tropical Storm Chanthu (Gener)
Originating from an area of low pressure on June 5, 2004, Chanthu was first declared a tropical depression near southern Leyte Island, in the Philippines, on June 7. Tracking west-northwestward, the depression intensified into a tropical storm over the central Philippines before entering the South China Sea. Once over the warm waters of the sea, the system quickly intensified, attaining its peak 10-minute winds of 110 km/h (68 mph) and 1-minute winds of 140 km/h (87 mph). On June 12, the storm made landfall in Vietnam before quickly weakening over land. By June 13, the system had weakened to a tropical depression and dissipated two days later.
During the time Typhoon Chanthu affected Vietnam, the highest sustained wind speed recorded on land was 65 km/h (40 mph) in An Nhơn (Bình Định), and the lowest recorded atmospheric pressure was 988.9 hPa (29.20 inHg) in Quy Nhơn.
In Vietnam, Chanthu wrought substantial damage and killed 38 people. Damage from the storm was estimated at 125 billion Vietnam dong (US$7.9 million), mostly from agricultural losses. The remnants of Chanthu also brought heavy rains to Cambodia, estimated to have exceeded 400 mm (16 in).
Typhoon Dianmu (Helen)
Tropical Depression 09W, which developed from the monsoon trough on June 13, headed north in the open Western Pacific. On the June 15 and 16, Dianmu rapidly intensified from a 70 kn/80 mph typhoon to a 155 kn/180 mph super typhoon, one of nine typhoons since 1990 to reach that intensity. It lost some organization on June 18, but re-strengthened on June 19 to a super typhoon while south of Okinawa. Some dry air weakened Dianmu as it continued its northward movement, and hit southern Japan as a 55 kn/65 mph tropical storm on June 21. Dianmu became extratropical that night after causing 3 deaths. Dianmu is the name of the goddess of thunder and lightning in Chinese folklore.
Typhoon Mindulle (Igme)
The monsoon trough spawned a tropical depression on June 23 near Guam. It tracked westward, becoming a tropical storm that night but slowly strengthening as it continued westward due to vertical wind shear. When the shear abated, Mindulle quickly intensified, reaching typhoon strength on June 27 and peaking at 125 kn/145 mph winds on June 28. Land interaction with Luzon to its south weakened Mindulle, and the typhoon weakened as it turned northward. On July 1, Mindulle hit eastern Taiwan, and after accelerating to the northeast became extratropical near South Korea on July 4.
Mindulle caused 56 deaths, with $833 million in damage in its path (2004 USD). Mindulle is the Korean word for the dandelion.
Typhoon Tingting
Tropical Depression 11W, which developed from the monsoon trough on June 25, steadily strengthened as it tracked to the northwest, and reached tropical storm status on June 26. Tingting passed Saipan on June 27, and reached typhoon status early on June 28. After maximum sustained winds peaked at 80 kn/90 mph, the typhoon turned to the northeast, where it became extratropical on July 3 after causing 3 deaths on Saipan. Tingting is a pet name for young girls in Chinese.
Tropical Storm Kompasu (Julian)
A non-tropical system formed south of an upper-level vortex on July 3. It moved west until it weakened due to an intensifying high-pressure area north of it on July 8. The next day, it regenerated and strengthened into a tropical disturbance. Late on July 11, it entered in a place of favorable environments until it became a Tropical Depression 12W early on July 12. Area of thunderstorms and convection organized into Tropical Depression 12W on July 13. Under high vertical shear and with a very small circulation, it was not expected to strengthen further. However, as it tracked erratically westward, it intensified, peaking with 40 kn/50 mph winds on July 14. Kompasu turned northward, hit the eastern part of Hong Kong directly as a minimal tropical storm, and dissipated on July 16. Kompasu is the Japanese word for compass, and the name of the constellation Circinus.
Typhoon Namtheun
Tropical Storm Namtheun, which formed on July 24, rapidly intensified on July 26 to a 115 kn/135 mph typhoon. Dry air approached the system from the south, and it weakened as it tracked northwest towards Japan. On July 31, Namtheun struck southwest Japan as a 55 kn/65 mph tropical storm, and became extratropical in the Sea of Japan on August 1. The storm caused no deaths or damage, with only 6 injuries. Namtheun is the name of a river in Laos.
Tropical Storm Malou
A low-pressure area formed from the outflow of Typhoon Namtheun on July 29. An area of convection under moderate to high vertical wind shear developed into a tropical depression southeast of Japan on August 4. It became a minimal tropical storm before hitting central Japan on the night of August 4. Malou turned to the northeast and became extratropical in the Sea of Japan on August 5. Malou is the Chinese name for the mineral agate.
Typhoon Meranti
Typhoon Meranti originated out of an area of low pressure about 475 km (295 mi) south of Wake Island on August 2. Little deep convection accompanied the weak system despite being situated within an area of moderate diffluence and weak to moderate wind shear. Initially, the system was thought to have been much closer to Wake Island; however, following the development of deep convection, the location of the center of circulation was corrected. Around 0000 UTC on August 3, the Japan Meteorological Agency (JMA), the Regional Specialized Meteorological Center for the western Pacific basin, designated the system as a tropical depression. Development continued as the depression moved into an area of divergence near a tropical upper-tropospheric trough cell. Several hours after the JMA issued their advisory on the depression, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert, stating that the system was likely to develop into a tropical storm within 24 hours. Later on August 3, the JTWC issued their first advisory on the storm, classifying it as Tropical Depression 14W. Located to the west of a mid-level ridge, the depression was steered towards the north. Early the next day, the JTWC upgraded 14W to a tropical storm; the JMA later upgraded it to a tropical storm around 1200 UTC. At that time, the storm received the name Meranti, a name that was contributed by Malaysia and refers to a type of tree. Little intensification took place until August 5, at which time convection became increasingly organized and underwent a brief period of rapid intensification. By 1200 UTC, both the JMA and JTWC upgraded Meranti to a typhoon. Several hours later, the storm reached its peak intensity; the JMA assessed it to have had winds of 140 km/h (87 mph) 10-minute winds) while the JTWC assessed it to have attained Category 2 status on the Saffir–Simpson hurricane scale with winds of 165 km/h (103 mph).