The 2001 Pacific typhoon season was an slightly above-average season with twenty-six named storms, sixteen typhoons and three super typhoons. It ran year-round in 2001, with most tropical cyclones in the northwestern Pacific Ocean tending between May and November.
The early season was relatively inactive, with the first named storm, Cimaron, not developing until May 9. Taiwan suffered the most destruction from typhoons this year, with Typhoons Toraji, Nari, and Lekima being responsible for nearly 300 deaths in that island alone, making it one of the deadliest typhoon seasons in recorded history in that island. In November, Typhoon Lingling impacted the Philippines, killing 171 people, making it one of the deadliest Philippine storms this century. The season ended with the formation of Tropical Storm Vamei during the last week of December. Vamei would be notable for becoming the lowest latitude tropical storm, at 1.4°N, ever to be observed in the Northwest Pacific.
The scope of this article is limited to the Pacific Ocean, north of the equator and west of the International Date Line. Storms that form east of the date line and north of the equator are called hurricanes; see 2001 Pacific hurricane season. Tropical storms that formed in the West Pacific basin are assigned a name by the Tokyo Typhoon Center. Tropical depressions in this basin have the "W" suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric, Geophysical and Astronomical Services Administration or PAGASA. This often results in the same storm having two names.
Seasonal forecasts
During the year, the Japan Meteorological Agency (JMA) issued advisories on tropical cyclones west of the International Date Line to the Malay Peninsula, and north of the equator, in its role as the official Regional Specialized Meteorological Center, as designated by the World Meteorological Organization in 1989. The JMA issued forecasts and analyses every six hours starting at midnight UTC using numerical weather prediction (NWP) and a climatological tropical cyclone forecast model. They used the Dvorak technique and NWP to estimate 10-minute sustained winds and barometric pressure. The JTWC also issued warnings on storms within the basin, operating from Pearl Harbor in Hawaii and supplying forecasts to the United States Armed Forces in the Indian and Pacific Oceans.
On January 31, Tropical Storm Risk (TSR) issued their extended range forecast for the Northwest Pacific in 2001, predicting near-average activity in terms of tropical storms, but a slightly below average in terms of typhoons. They predict that around 28 tropical storms would form, in which 17 of them would become typhoons, and 8 would further intensify to intense typhoons. TSR uses anomalous patterns of sea-surface temperatures (SSTs) over in the Niño 3.4 region (5°N-5°S, 120°W-170°W) during the August–September SST forecast as a predictor. With a predicted anomaly of −0.27 °C, a weak La Niña is expected — which tends to suppress tropical cyclone activity or intensity. On June 15, TSR issued their pre-season forecast, predicting a neutral typhoon season. Predicted tropical storm numbers have decreased to 26, but both their predicted typhoon and intense typhoon numbers have increased to 18 and 9, respectively. The key factor to this prediction is now due to the anticipated neutral value for the August–September SST forecast in the Niño 4 region (5°S – 5°N, 150°W – 160°E) of +0.27 °C.
Seasonal summary
The Accumulated Cyclone Energy (ACE) index for the 2001 Pacific typhoon season as calculated by Colorado State University using data from the Joint Typhoon Warning Center was 307.3 units. 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).
The season ran with weak La Niña conditions during the first quarter of the year and near-normal conditions throughout the rest of the year, with average sea-surface temperatures in the Niño 3.4 region of around −0.3 °C. It was the final year of a rather strong La Niña episode that persisted throughout most of the Pacific Ocean since 1998. This was demonstrated with this season's tropical activity being more active than the previous three seasons, but overall tropical activity still remaining below average.
2001 opened with Tropical Storm Soulik, from the previous season, active in the Philippine Sea. Soulik strengthened into the first typhoon seen this year and reached its peak intensity as a Category 3-equivalent typhoon on January 3, before quickly dissipating the next day. The formation of Tropical Depression 01W (Auring), however, officially initiated the start of the annual typhoon season on February 17. No tropical cyclones developed until after two months later, when another tropical depression had developed to the southeast of the Philippines. Tropical cyclogenesis gradually increased when May arrived – with three tropical systems developing. Two of these systems were only recognised as minor tropical depressions, while the other strengthened to the first official named storm of this year, Cimaron, which moved through the Philippine archipelago in the middle of the month.
Systems
Severe Tropical Storm Cimaron (Crising)
A weak low-level circulation center (LLCC) south of Koror developed from a monsoon trough on May 4. The system was later upgraded to a tropical depression and was assigned 03W by the JTWC on May 7, before the JMA followed suit in upgrading its status on May 9, and at the same time, was assigned the name Crising by PAGASA after it entered its responsibility area. The following day, Tropical Depression 03W intensified to a tropical storm and was given the name Cimaron by the JMA. The storm was weakened by vertical wind shear on May 12, before it resumed intensifying and by May 13, was upgraded to a severe tropical storm after attaining 10-minute sustained winds of 95 km/h (60 mph). Cimaron slowly began to transition into an extratropical cyclone due to a weakening trend with vertical shear as the storm accelerated northeastward. Cimaron passed over 148 km (92 mi) southwest of Naha, Okinawa on May 14, before transitioning into an extratropical cyclone and becoming last noted by the JMA on May 15.
After having become an extratropical cyclone, strong winds struck the Ishigaki Island on May 14 and caused a building to collapse and also damage a plastic greenhouse. The damages in the island were estimated at ¥26.4 million (US$217 thousand) Furthermore, at Miyako Island, an additional ¥139 million (US$1.14 million) of damages occurred, and 22 flights were cancelled for 14 days. The storm later approached Okinawa, and around 20,000 people were affected, due to roads being flooded, and land transportation was crowded. A landslide out of three occurred in Naha City, resulting in 19 people evacuating and a household losing power. The overall damages in Okinawa totaled ¥318 million (US$2.62 million).
Typhoon Chebi (Emong)
On June 19, an area of convection developed southeast of Yap and by 18:00 UTC, was centered 278 km (173 mi) east-northeast of Palau. Rapid development occurred and the disturbance became identified as Tropical Depression 04W by the JTWC at 21:00 UTC. After entering the PAR and receiving the name Emong by PAGASA, the depression intensified into a tropical storm on June 20. Chebi headed northwest while being located east of the Philippines on June 21 at 06:00 UTC, and would later attain severe tropical storm intensity, before intensifying further to a typhoon the following day. Chebi reached its peak intensity on June 23, before a trough forced Chebi west and northwest where it made landfall near Fuzhou City, China. Chebi rapidly weakened while accelerating northward, and would degrade into an extratropical cyclone on June 24. Its remnants were last noted by the JMA along with other weather centers before dissipating on June 30.
Chebi killed 82 people, mostly in China, and left $422 million (2001 USD), $457 million (2005 USD). Chebi's heavy rains and strong winds left nine people dead, 28 missing and $13 million (2001 USD) in damage in the Philippines. Four of the nine were from a Belizean freighter that sank during the storm. The Penghu Islands, which took the brunt of the typhoon, suffered considerable damage as 102 fishing boats sank and ten thousand people were left without power. The storm also crippled ground and air traffic. A rain laden typhoon, Chebi produced 100 millimeters of rain across Guangdong. About 73 people were killed in China, most of them in the southeastern province of Fujian. The storm also destroyed several thousand acres of crops, resulting in economic losses. In Ningde, about 321,400 houses were destroyed by the typhoon. About 22 people were killed in Hangzhou when a landslide burst through a construction wall.
Severe Tropical Storm Durian
The monsoon trough produced another disturbance that upgraded into a tropical depression to the west of Luzon on June 29. The tropical depression tracked northwestward while a subtropical ridge influenced the depression and caused it to upgrade to Tropical Storm Durian on June 30. The storm attained severe tropical storm status at 18:00 UTC the same day, with 10-minute winds of 110 km/h (70 mph) and 1-minute winds of 140 km/h (85 mph), making it equivalent to Category 1 winds on the Saffir–Simpson scale. Durian had an atmospheric pressure of 970 hPa (29 inHg). Durian made landfall on the Leizhou Peninsula, before rapidly weakening as it continued in the same direction before the JTWC stopped advisories of the storm on July 2, with the JMA doing the same the following day.
The name Durian was submitted by Thailand and refers to the Southeast Asian fruit of the same name. Throughout the provinces of Guangdong, Guangxi, and Hainan, more than 4.3 million people were affected, with over 13 thousand houses being destroyed. 21 people went missing off the coast of Guangdong. Zhanjiang suffered agricultural damage, with sugarcane fields and banana trees being destroyed and the deaths of over 52 thousand farm animals. Overall, Durian caused 65 deaths and 4.5 billion yuan ($449 million) in China, and over 500 people were reported injured. An injury also occurred in Hong Kong. In Northern Vietnam, 32 people were killed and 3 people went missing, with more than 20 thousand homes being destroyed by flooding. Durian was responsible for some of the worst flooding in Northern Vietnam for 40 years, with rainfall of up to 17 inches between July 2 and 4. The Vietnamese military sent amphibious vehicles to aid rescue efforts in the province of Thái Nguyên.
Severe Tropical Storm Utor (Feria)
Utor spawned from an area of convection that developed off 907 km (565 mi) south-southeast of Guam on June 26, that remained quasi-stationary for 2 days before upgrading to a tropical depression on July 1 due to favorable conditions such as low vertical shear. The depression strengthen into a tropical storm at 00:00 UTC on July 2. Utor tracked west-northwest from a peripheral ridge and developed further, after entering the Philippine Area of Responsibility, and attained severe tropical storm status the following day. Utor was a large cyclone, with gale-force wind of 250 nmi (465 km; 290 mi). Utor reached its peak strength on June 4, with 10-minute winds of 110 km/h (70 mph) and 1-minute winds of 150 km/h (95 mph), with the barometric pressure of 960 hPa (28 inHg). Utor was centered 56 km (35 mi) near northern Luzon and tracked northwesterly as it began to weaken. The storm made landfall near the east of Hong Kong on July 5 and quickly weakened before being last noted on July 7 by the JMA.
Utor, while not a very strong storm, brought heavy rain amounting to $297.2 million (2001 USD) in damage, as well as causing 203 fatalities.
Tropical Storm Trami (Gorio)
Tropical Storm Trami originated from a disturbance that developed about 222 km (138 mi) northwest of Chuuk on July 3. Bursts of deep convection near the center were observed on the 7th, although the system remained disorganized. Organization improved and by July 8, was upgraded to a tropical depression. Moving northwestward, the system gradually intensified, and the PAGASA began initiating advisories on 18:00 UTC of the same day, naming the system, Gorio. Six hours later, the JTWC already deemed the system as Tropical Depression 07W. Deep convection persisted to the west of its well-defined, but a partially exposed center. Thus, the system gained strength into a tropical storm, with the JMA naming it as Trami. Northeasterly shear prevented the storm to significantly intensify, and therefore Trami maintained tropical storm intensity for a day — only peaking with 10-minute sustained wind speeds of 75 km/h (45 mph). By 12:00 UTC of July 11, Trami moved over Taiwan and into the Taiwan Strait, where Trami rapidly weakened and dissipated. No other storm weakened into a tropical depression over Taiwan until Typhoon Krathon did so on October 4, 2024.
Trami mostly affected Taiwan with just rainfall. However, Kaohsiung and Pingtung counties experienced the heaviest rainfall in 40 years. In Kaohsiung City, streets were clogged with bonded cars due to severe flooding, and more than 100,000 homes were left without power. The floods resulted in only five deaths in the southern part of the city.