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Extremely Powerful Typhoon Meranti Nearing Southern Taiwan

The center of extremely powerful Typhoon Meranti moved closer to the southern end of Taiwan during the past few hours.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Meranti was located at latitude 21.1°N and longitude 121.3°E which put it about 65 miles (105 km) south-southeast of Hengchun, Taiwan.  Meranti was moving toward the west-northwest at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 190 m.p.h. (305 km/h) and there were wind gusts to 230 m.p.h. (370 km/h).  The minimum surface pressure was 887 mb.

Typhoon Meranti is large and powerful.  The Hurricane Intensity Index (HII) is 46.1.  The Hurricane Size Index (HSI) is 27.9 and the Hurricane Wind Intensity Size Index (HWISI) is 74.0.  As a source of comparison, when Hurriane Katrina was at its peak intensity as a Category 5 hurricane over the Gulf of Mexico in 2005, its HII was 38.6, its HSI was 33.7, and its HWISI was 72.3.  Typhoon Meranti is stronger than Hurricane Katrina was, but Meranti is a little smaller than Katrina was in 2005.  The indices suggest that Typhoon Meranti is capable of causing widespread catastrophic damage.

The circulation of Typhoon Meranti is symmetrical and very well organized.  It possess a tight core consisting of a small inner eye surrounded by a ring of very tall thunderstorms.  A second, larger outer eyewall completely surrounds the inner eye.  The strongest winds are occurring in the inner eyewall near the center of circulation.  Winds to typhoon force are also occurring in the outer eyewall and extend out at least 80 miles (130 km) from the center of circulation.  Additional bands of strong thunderstorms are rotating around the outer eyewall.  Typhoon Meranti is generating strong upper level divergence which is pumping out large quantities of mass and is allowing the surface pressure to be so low.

Typhoon Meranti is probably at its peak intensity.  It is still moving over water where the Sea Surface Temperature is near 31°C.  However, the northwestern edge of the outer eyewall appears to be moving over the southern end of Taiwan.  As more of the circulation moves over Taiwan, there will be some disruption of the airflow.  The center of Typhoon Meranti could move very close to the southern tip of Taiwan.  If the center of Meranti moves over southern Taiwan, then the typhoon will weaken more quickly.  It currently appears that the center of Typhoon Meranti could move just south of the southern tip of Taiwan, and on that track the typhoon would not weaken as quickly.  When Typhoon Meranti moves west of Taiwan, it will move over slightly cooler SSTs before it reaches China.  Meranti will weaken more before it reaches China, but it will still be a significant typhoon when it makes landfall there.

The center of Typhoon Meranti is wobbling a little as the inner eye rotates around inside the outer eyewall.  If one averages the wobbles, then then core of Meranti is moving on a general west-northwesterly track.  On its anticipated track, the center of Typhoon Meranti will pass very near the southern end of Taiwan during the next few hours.  It could turn slightly toward the northwest as it moves west of Taiwan.  Typhoon Meranti could make a landfall on the coast of China between Xiamen and Shantou in about 24 hours.

Typhoon Meranti is an extremely dangerous storm.  It is capable of causing widespread catastrophic wind damage.  In addition, its intensity and size will produce very heavy rainfall, especially on the eastern slopes of the mountains on Taiwan.  Flash flooding is likely.  Typhoon Meranti will also produce heavy rain over eastern China and additional flooding is likely in that region.  Typhoon Meranti will also cause a significant storm surge in low lying coastal areas.

Typhoon Meranti Becomes Equivalent of Cat. 5 Hurricane and Threatens Taiwan

Typhoon Meranti rapidly intensified into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale as it moved on a course that threatens Taiwan.  At 11:00 a.m. EDT on Monday the center of Typhoon Meranti was located at latitude 19.2°N and longitude 127.6°E which put it about 495 miles (800 km) southeast of Taiwan.  Meranti was moving toward the west-northwest at 14 m.p.h. (23 km/h).  The maximum sustained wind speed was 180 m.p.h. (290 km/h) and there were wind gusts to 220 m.p.h. (355 km/h).  The minimum surface pressure.

Meranti is a large dangerous typhoon.  The Hurricane Intensity Index (HII) is 42.2.  The Hurricane Size Index (HSI) is 25.5 and the Hurricane Wind Intensity Size Index (HWISI) is 67.7.  Those indices suggest that Typhoon Meranti is capable of causing widespread catastrophic damage.

The structure of Typhoon Meranti is very well organized.  A well formed circular eye is surrounded by a ring of very tall thunderstorms.  Additional strong spiral bands of thunderstorms are rotating around the core of the circulation.  Typhoon Meranti is generating strong upper level divergence which is pumping out mass in all directions.

Typhoon Meranti is moving through an environment that will allow it to maintain much of its intensity until it reaches Taiwan.  It is moving over water where the Sea Surface Temperature is near 31°C.  The upper level winds are weak and there is not much vertical wind shear.  If a rainband wraps around the existing eye, then an eyewall replacement cycle could temporarily weaken Typhoon Meranti.

A subtropical ridge is steering Typhoon Meranti toward the west-northwest and that general motion is expected to continue for several more days.  On its anticipated track Typhoon Meranti will be very near the southern tip of Taiwan in about 36 hours.  After it moves past Taiwan it is forecast to move into eastern China.

Meranti is an extremely dangerous typhoon.  It is capable of causing widespread catastrophic wind damage.  In addition it will produce very heavy rain and flooding is a serious concern.

Typhoon Meranti Strengthens Quickly Into the Equivalent of a Major Hurricane

Typhoon Meranti intensified rapidly on Sunday into the equivalent of a major hurricane.  At 11:00 p.m. EDT on Sunday the center of Typhoon Meranti was located at latitude 18.1°N and longitude 129.7°E which put it about 650 miles (1050 km) east-southeast of Taiwan.  Meranti was moving toward the west-northwest at 17 m.p.h. (27 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 948 mb.

Typhoon Meranti intensified very rapidly on Sunday.  A small, well formed eye developed at the center of Meranti.  A ring of strong thunderstorms surrounds the eye and additional bands of thunderstorms are spiraling around the core of the circulation.  The circulation is very symmetrical.  Thunderstorms in the core of Typhoon Meranti are generating strong upper level divergence which is pumping out large amounts of mass in all directions.  Meranti is a very well organized typhoon.

Typhoon Meranti is moving through a very favorable environment. It is moving over water where the Sea Surface Temperature is near 31°C.  The upper level winds are weak and there is little vertical wind shear.  Meranti will continue to intensify and it could become a Super Typhoon.  If an eyewall replacement cycle occurs, there could be fluctuations in the intensity of Meranti.

A subtropical ridge is steering Typhoon Meranti toward the west-northwest and that general motion is expected to continue for another couple of days.  On its anticipated track Typhoon Meranti will be near northern Luzon, Taiwan and the southern Ryukyu Islands in about 48 hours.  Meranti will be a dangerous typhoon at that time.  It will be capable of significant wind damage.  It will also cause very heavy rain and create the potential for significant flooding.

Tropical Storm Meranti Forms West of Guam

A center of circulation developed within an area of thunderstorms west of Guam on Saturday and the system was designated as Tropical Storm Meranti.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Meranti was located at latitude 16.0°N and longitude 135.8°E which put it about 1070 miles (1725 km) east-southeast of Taiwan.  Meranti was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 991 mb.

The circulation of Tropical Storm Meranti is still organizing and the distribution of thunderstorms is asymmetrical.  Most of the thunderstorms are occurring east of the center of circulation.  There is a cluster of the thunderstorms just to the east of the center.  There are also two well formed rainbands east of the core of Tropical Storm Meranti.  Additional spiral bands are located in all parts of the tropical storm.  The thunderstorms near the center are generating upper level divergence which is pumping out mass in all directions.

Tropical Storm Meranti is moving through an environment which is favorable for further intensification.  It is moving over water where the Sea Surface Temperature is near 31°C.  An upper level ridge located to the northwest of Meranti is producing northeasterly winds which are blowing across the western portion of the tropical storm.  The upper level winds are weaker over the eastern half of the circulation and the vertical wind shear is only slowing the intensification.  Although there may be some drier air in the western half of the circulation, Tropical Storm Meranti could intensify into a typhoon on Sunday.  Meranti could become a strong typhoon in two or three days.

A subtropical ridge north of Tropical Storm Meranti is steering it toward the west.  The subtropical ridge is forecast to steer Meranti in a general west-northwesterly direction during the next two or three days.  On its anticipated track Tropical Storm Meranti is expected to approach the area of northern Luzon, Taiwan and the southern Ryukyu Islands in about three days.  It could be a strong typhoon at that time.

Lionrock Becomes a Typhoon East of Okinawa

Tropical Storm Lionrock intensified into a typhoon east of Okinawa on Tuesday.  At 8:00 p.m. EDT on Tuesday the center of Typhoon Lionrock was located at latitude 25.3°N and longitude 132.8°E which put it about 340 miles (550 km) east-southeast of Okinawa.  Lionrock was moving toward the south-southwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 965 mb.

Lionrock is a fairly small typhoon.  Winds to tropical storm force only extend out about 150 miles (240 km) from the center.  The circulation of Typhoon Lionrock is very well organized.  A small distinct eye is visible on satellite imagery.  The eye is surrounded by a ring of strong thunderstorms.  Additional spiral rainbands are rotating around the core of Lionrock.  The thunderstorms around the eye are generating upper level divergence which is pumping out mass in all directions.

Typhoon Lionrock is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30.5°C.  The upper level winds are weak and there is little vertical wind shear.  A small typhoon like Lionrock can intensify very quickly and it appears to be doing so.

An upper level ridge over China is steering Typhoon Lionrock slowly toward the south-southwest and that general motion is expected to continue for another day or two.  Lionrock could move into an area where the steering winds are weak and it could stall for a period of time.  Eventually, an upper level trough is expected to approach the area from the west and begin to pull Lionrock toward the north.

Typhoon Nida Makes Landfall Near Hong Kong

Typhoon Nida made landfall on Monday near Hong Kong on the coast of China.  At 5:00 p.m. EDT on Monday the center of Typhoon Nida was located at latitude 22.8°N and longitude 114.4°E which put it about 50 miles (80 km) east-northeast of Hong Kong.  Nida was moving toward the northwest t 13 m.p.h.  The maximum sustained wind speed was 95 m.p.h. (155 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 963 mb.

Typhoon Nida made landfall on the southeast coast of China just to the north of Hong Kong.  The core of Nida is large and the typhoon is capable of causing wind damage on a regional scale.  Wind blowing toward the coast could also generate a storm surge until Typhoon Nida moves farther inland.  However, very heavy rain and fresh water flooding are much greater risks as Nida moves farther inland over China.

A subtropical ridge north of Nida is steering the typhoon toward the northwest and that general motion is expected to continue for the next several days.  The ridge will steer Nida farther inland over southeastern China.  Typhoon Nida’s fairly slow motion and large size mean that heavy rain could fall over an expansive area.  The risk for flooding will continue as Nida moves inland.

Typhoon Nida Brushes Luzon and Heads for Hong Kong

Typhoon Nida brought wind and rain to northern Luzon on Sunday as it continued to move toward Hong Kong on the coast of China.  At 11:00 p.m. EDT on Sunday the center of Typhoon Nida was located at latitude 20.4°N and longitude 118.3°E which put it about 340 miles (545 km) east-southeast of Hong Kong.  Nida was moving toward the west-northwest at 17 m.p.h. (27 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 974 mb.

The Hurricane Intensity Index (HII) for Typhoon Nida is 10.4.  The Hurricane Size Index (HSI) is 13.1 and the Hurricane Wind Intensity Size Index (HWISI) is 23.5.  These indices suggest that Typhoon Nida will be capable of causing minor wind damage on a regional scale.

The structure of Typhoon Nida changed significantly on Sunday.  The primary rainband wrapped around the core of the circulation and a very large eye was created at the center.  The diameter of the eye is approximately 50 miles (80 km).  The strongest winds are occurring in the ring of thunderstorms that surrounds the eye.  Other spiral bands of thunderstorms are rotating around the large eye.  The thunderstorms were generating upper level divergence which pumped out mass and allowed the surface pressure to decrease.

Typhoon Nida is in an environment that would favor intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  Easterly winds are blowing in the upper levels, but there is not much vertical wind shear.  The large size of the eye of Nida is the major factor inhibiting intensification.  It takes more energy to increase the wind speed in a large typhoon than it does in a smaller storm.  If the eye contracts, then Typhoon Nida could intensify more before it makes landfall.

A subtropical ridge north of Nida is steering the typhoon toward the west-northwest and that general motion is expected to continue for another day or so.  On its anticipated track Typhoon Nida will be very near Hong Kong in about 24 hours.

As mentioned above, the large size of Typhoon Nida means that it will be capable of causing wind damage on a regional scale.  In addition, Typhoon Nida will be capable of creating a significant storm surge when it moves into the coast of China.  A large slow moving typhoon like Nida will also produce heavy rain and flooding as it moves inland.

Intensifying Tropical Storm Nida Nears Northern Philippines

Tropical Storm Nida intensified on Saturday as it slowly approached the northern portion of Luzon in the Philippines.  At 5:00 p.m. EDT (2100 UTC) the center of of Tropical Storm Nida was located at latitude 16.5°N and longitude 123.8°E which put it about 245 miles (395 km) east-northeast of Manila, Philippines.  Nida was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 50 m.p.h. (95 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 989 mb.

The circulation of Tropical Storm Nida has become increasingly well organized during the past 24 hours.  A primary rainband wraps about two thirds of the way around the western and southern sides of the center of circulation.  Additional spiral bands of thunderstorms are developing outside the core of the circulation.  Rising motion associated with the convection is generating upper level divergence which is pumping out mass and allowing the surface pressure to decrease.

Tropical Storm Nida is moving through an environment that is very favorable for further intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 31°C.  Nida is beneath an upper level ridge where the upper level winds are light and there is little vertical wind shear.  Very warm SSTs and little wind shear will allow the circulation of Tropical Storm Nida to consolidate further and it should continue to intensify.  Nida could intensify rapidly once an eye starts to form at the center of circulation.  Tropical Storm Nida will move near or over the northeastern part of Luzon.  Interaction with land could slow or temporarily stop the intensification.  However, Tropical Storm Nida should intensify further after it move wests of the Philippines.

A subtropical ridge north of Nida is steering the tropical storm toward the west-northwest and that general motion is expected to continue.  On its anticipated track Tropical Storm Nida could move over the northern part of Luzon during the next 12 to 24 hours.  Nida could approach the area around Hong Kong as a typhoon in about 48 hours.

The primary threats posed by Tropical Storm Nida to the Philippines are locally heavy rain and flash floods.  Tropical Storm Nida could generate very heavy rain in locations where the circulation causes the wind to blow up the slopes of mountains.  Heavy rain falling on steep terrain in those locations could also cause flash flooding.  Nida could be a typhoon by the time it reaches the part of China near Hong Kong.  Nida will be capable of producing some wind damage and storm surge in addition to heavy rain and flooding when it reaches the coast of China.

Weakened Tropical Storm Nepartak Still Bringing Rain to Parts of China and Taiwan

Although Tropical Storm Nepartak was weakened significantly during its passage over the mountains on Taiwan, it is still producing heavy rain over portions of eastern China and Taiwan.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Nepartak was located at latitude 24.0°N and longitude 119.0°E which put it about 100 miles (160 km) east-southeast of Xiamen, China.  Nepartak was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were wind gusts to 85 m.p.h. (140 km/h).  The minimum surface pressure was 978 mb.

Typhoon Nepartak brought damaging winds and heavy rainfall to Taiwan when the core of the tropical cyclone passed over that area.  The mountains on Taiwan significantly disrupted the lower levels of the circulation.  There are some indications on satellite imagery that the upper portion of the circulation is located northwest of the surface center.  When a typhoon crosses Taiwan, the mountains can cause the original center of circulation to weaken and a new center can sometimes form over the water on the downstream side of the island.

In any case, crossing over Taiwan caused Nepartak to weaken to a tropical storm and the circulation no longer exhibits a tight inner core.  However, there are still rainbands that are producing heavy rain and wind speeds to almost typhoon force.   Because Nepartak no longer has a tight inner core, it is unlikely to intensify significantly before the centers moves into eastern China.

A ridge northeast of Nepartak is steering the tropical storm toward the northwest and that general motion is expected to continue for the next 12 to 24 hours.  After that time Nepartak is expected to turn toward the north.  On its anticipated track Tropical Storm Nepartak will make landfall in China between Xiamen and Fuqing on Saturday.

Tropical Storm Nepartak could produce locally heavy rainfall over portions of eastern China.  Some of that region has already received a lot of rain from other weather systems.  So, the potential for additional flooding is high in some areas.

Typhoon Nepartak Pounding Taiwan

Typhoon Nepartak is pounding Taiwan with strong winds and heavy rain.  The eye will make landfall during the next few hours near T’aitung.  At 5:00 p.m. EDT on Thursday the center of Typhoon Nepartak was located at latitude 22.7°N and longitude 121.4°E which put it about 185 miles (305 km) south of Taipei, Taiwan.  Nepartak was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 926 mb.

Typhoon Nepartak is the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The Hurricane Intensity Index (HII) for Nepartak is 31.5.  The Hurricane Size Index (HSI) is 20.5, and the Hurricane Wind Intensity Size Index (HWISI) is 52.0.  These indices mean that Typhoon Nepartak is capable of causing widespread significant damage as it crosses Taiwan.

In addition to the strong winds locally heavy rain could cause flash floods, especially in the mountains of Taiwan.

The circulation of Typhoon Nepartak is very well organized.  It has a well formed eye which is surrounded by a ring of strong thunderstorms.  Numerous rainbands are rotating around the typhoon.

The atmospheric environment is favorable for strong tropical cyclones.  The winds in the upper levels are weak and there is little vertical wind shear.  However, the mountains on Taiwan will disrupt the lower part of the circulation and Typhoon Nepartak will weaken significantly when it crosses the island.  It will take about 12 hours for the typhoon to move across Taiwan.  Nepartak could still be a typhoon when the center emerges over the Taiwan Strait on Friday.

Typhoon Nepartak is expected to also make landfall on the east coast of China between Xiamen and Fuzhou.  Although it will be much weaker, Nepartak could cause some wind damage when it reaches China.  However, heavy rain will be a greater risk because it cause significant flooding in parts of eastern China.