Tropical Storm Linfa (2015)

Severe Tropical Storm Linfa (Egay)

Severe tropical storm (JMA scale)
Category 1 (Saffir–Simpson scale)
Tropical Storm Linfa near its peak strength southwest of Taiwan on July 8
Formed	July 1, 2015
Dissipated	July 10, 2015
Highest winds	10-minute sustained: 95 km/h (60 mph) 1-minute sustained: 120 km/h (75 mph)
Lowest pressure	980 hPa (mbar); 28.94 inHg
Fatalities	None
Damage	$217.8 million (2015 USD)
Areas affected	Philippines, Taiwan, China
Part of the 2015 Pacific typhoon season

Severe Tropical Storm Linfa, known in the Philippines as Severe Tropical Storm Egay, was a tropical cyclone which affected the northern Philippines, Taiwan and southern China in early July 2015. The tenth named storm of the annual typhoon season, Linfa was first discovered as a weak tropical disturbance over in the Philippine Sea, embedded in an active Intertropical Convergence Zone on June 30. The disturbance gradually intensified, and was upgraded to a tropical depression by the JMA and PAGASA on July 1. The JTWC followed suit the next day, whilst the JMA upgraded the depression to Tropical Storm Linfa.

Both Linfa and Chan-hom, combined with the southwest monsoon, brought heavy rainfall and flooding throughout the Philippines for several days.

Meteorological history

Map plotting the track and intensity of the storm according to the Saffir–Simpson hurricane wind scale

Toward the end of June, a westerly wind burst moved across the western Pacific Ocean, spawning Typhoon Chan-hom as well as the storm that would become Linfa.^[1] On July 1, a large area of convection persisted east of the Philippines, with an associated circulation exposed due to moderate wind shear. At 06:00 UTC that day, the Joint Typhoon Warning Center (JTWC) assessed a low probability of tropical cyclogenesis over the subsequent 24 hours.^[2] However, the system quickly organized, prompting the JTWC to issue a tropical cyclone formation alert later that day, indicating that a storm would likely form imminently.^[3] At 18:00 UTC on July 1, the Japan Meteorological Agency (JMA) estimated that a tropical depression developed about 500 km (300 mi) east-northeast of the Philippine island of Samar.^[4] Early the next day, the JTWC classified the system as Tropical Depression 10W, based on the organization of the rainbands about the center.^[5] PAGASA – the Philippines' weather agency – also began monitoring the system, giving it the local name Egay.^[6]

With the subtropical ridge to the northeast, the nascent system moved northwestward initially.^[5] Despite persistent shear dislocating the convection,^[7] the JMA upgraded the system to a tropical storm at 12:00 UTC on July 2, naming it Linfa.^[4] The storm slowly intensified, amplified by good outflow to the south and the presence of warm water temperatures.^[8] On July 3, Linfa's track briefly shifted to the southwest, by which time the convective structure had evolved into a central dense overcast.^[9] There was uncertainty in the storm's future as it approached the Philippines. This was due to potential interaction with Typhoon Chan-hom to the northeast, and differences in storm models whether an approaching trough would turn Linfa to the east or the west.^[10]

After turning back to the northwest, the convection around Linfa became even more symmetrical, although the circulation became slightly elongated.^[11] At 06:00 UTC on July 4, the storm reached a preliminary peak intensity, with 10 minute sustained winds of 85 km/h (50 mph) according to the JMA.^[4] As Linfa neared the northern Philippines, the bulk of the convection was shifted to the southern periphery, due to the continued wind shear.^[12] Late on July 4, the center of Linfa made landfall over Palanan, Isabela, on the island of Luzon.^[13][14] Moving westward across the island, the circulation became disorganized as the core convection diminished.^[15] By late on July 5, Linfa emerged into the South China Sea.^[4] Once over open waters, Linfa began moving to the north-northwest, still moving around the subtropical ridge, and it was expected to move over Taiwan. The circulation remained well-defined but exposed, with the deep convection displaced to the south.^[16] With the isolated thunderstorms and unfavorable wind shear, the JTWC noted the potential for the circulation to dissipate over open waters.^[17] By July 7, easing wind shear allowed the convection to rebuild and for the structure to improve in organization. By that time, the future of the storm was still uncertain, although a turn to the northwest toward China was expected.^[18] Also on July 7, PAGASA issued its final bulletin on the storm as Linfa exited their area of responsibility.^[19]

More favorable conditions allowed the storm to intensify more on July 8. Around that time, the storm turned more to the northwest due to a ridge exiting China, bringing the storm southwest of western Taiwan.^[20] At 00:00 UTC on July 8, the JMA estimated peak 10 minute winds of 95 km/h (60 mph), making it a severe tropical storm.^[4] The JTWC assessed further strengthening, upgrading Linfa to typhoon status at 18:00 UTC that day based on a developing well-defined eye. At that time, the agency estimated peak 1 minute winds of 120 km/h (75 mph).^[21] As the storm approached the southern China coast, the eye expanded to a diameter of 37 km (23 mi), while the thunderstorms on the northern periphery diminished.^[22] Around 03:00 UTC on July 9, Linfa made landfall east of Hong Kong, and it quickly weakened once over land.^[23] The storm turned westward, inland and parallel to the southern Chinese coastline. As the thunderstorms diminished, the surface sustained winds continued to drop.^[24] At 18:00 UTC on July 9, the JTWC issued their final advisory for Linfa,^[25] and shortly after the JMA downgraded the storm to a tropical depression. The system turned to the southwest, dissipating over open waters on July 10 off the coast of Guangdong province.^[4]

Preparations and impact

Three simultaneously active typhoons on July 9: (from left to right) Linfa, Chan-hom and Nangka

In its formative stages, Linfa brought light rainfall to Palau and Yap, causing minimal effects.^[1]

Linfa was originally forecast to move northwards and make landfall in Taiwan. However, Linfa curved to the west and hit Southern China instead. Only heavy rains and gusty winds were felt in Southern and Central Taiwan.^[26]

Philippines

On July 4, according to PAGASA's advisory at that time, Linfa (known as Egay) has maintained its intensity as it continued to move closer to Luzon. With this, Public Storm Warning Signal (PSWS) #2 was raised over Isabela, Quirino and Aurora whilst the rest of most areas over Luzon was at PSWS #1.^[27] The Provincial Disaster Risk Reduction Management Council (PDRRMC) was on heightened alert following the storm's landfall in Palanan, Isabela province in the late evening of that day.^[28] Due to the enhancement of the southwest monsoon by Egay, all ships in the Port of Manila were ordered to remain in harbor and some flights were cancelled in northern Luzon, while schools were closed in Metro Manila on July 6 through 8 due to flooding and landslides.^[29]

In the Ilocos region where Linfa lingered throughout July 4, a Chinese fishing vessel docked at Currimao port ran aground after being battered by huge waves.^[30] Throughout the region, 1,603 families from the provinces of La Union, Pangasinan and Ilocos Sur were also evacuated from their homes.^[29] La Union province declared a state of calamity on July 6 because of the storm.^[31]

According to the NDRRMC, no casualties were reported while total damages had reached ₱214.6 million ($4.8 million USD).^[32]

China

According to preliminary estimates in southern China, economic losses from the storm reached ¥1.2 billion (US$213 million). A total of 288 homes collapsed and 56,000 people were displaced.^[33] A wind gust of 171 km/h (106 mph) was observed in Jieyang.^[34]

As Linfa posed a threat of a direct hit with typhoon intensity, Hong Kong Observatory issued No. 8 NW Gale or Storm Signal at 4:40 p.m. local time on 9 July. However, local winds peaked in the afternoon and gradually decreased after Signal No. 8 was issued due to rapid weakening of the system, despite the fact that Linfa was the first storm to directly hit Hong Kong since Typhoon Usagi in 2013. Gale-force winds were not recorded in the territory during the issuance of No. 8 NW Signal, making this the weakest Signal No. 8 in at least 40 years. Linfa was the closest to HK when it skirted 50 km north of the Observatory Headquarters at 9:00PM. Shortly afterwards, the Observatory issued Strong Wind Signal No. 3 at 10:10 p.m. to replace Signal No. 8.^[35]

The storm resulted in the closure of Hong Kong International Airport on July 9. Approximately 1,020 flights were cancelled and rescheduled because of Linfa.^[36]

See also

• Tropical Storm Fung-wong (2014)
• Tropical Storm Nock-ten (2011)
• Tropical Storm Cimaron (2013)

References

External links

Wikimedia Commons has media related to Severe Tropical Storm Linfa (2015).

• JMA General Information of Tropical Storm Linfa (1510) from Digital Typhoon

Tropical cyclones of the 2015 Pacific typhoon season TD TD STS Mekkhala TY Higos TS Bavi TY Maysak TS Haishen TY Noul TY Dolphin TS Kujira TY Chan-hom STS Linfa TD TD TY Nangka TY Halola TD TD TD TD TD TD TD 12W TY Soudelor TD 14W TS Molave TY Goni TY Atsani TY Kilo STS Etau TS Vamco TY Krovanh TY Dujuan TY Mujigae STS Choi-wan TD 08C TY Koppu TY Champi TD TD TD 26W TY In-fa TY Melor TD Onyok TD TD Book Category Portal WikiProject Commons