Category Archives: Tropical Cyclones

Information about tropical cyclones

Large Typhoon Maysak Churns Toward South Korea

Large, powerful Typhoon Maysak churned toward South Korea on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Maysak was located at latitude 30.1°N and longitude 126.9°E which put it about 405 miles (655 km) south-southwest of Busan, South Korea.  Maysak was moving toward the north-northeast at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 932 mb.

Typhoon Maysak neared the completion of an eyewall replacement cycle on Tuesday which resulted in an increase in the size of the circulation.  The original inner eyewall had not quite dissipated, but low level convergence was focused on the much larger outer eyewall.  Winds to typhoon force extended out 90 miles (145 km) from the center of circulation.  Winds to tropical storm force extended out 240 miles (390 km) from the center of Maysak.

Typhoon Maysak was a large, dangerous tropical cyclone.  The Hurricane Intensity Index (HII) was 25.1.  The Hurricane Size Index (HSI) was 27.5 and the Hurricane Wind Intensity Size Index (HWISI) was 52.6.  Typhoon Maysak was capable of causing widespread major damage.

Since Typhoon Maysak was near the end of an eyewall replacement cycle, it will likely weaken slowly during the next 18 hours.  Maysak will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over eastern Asia will approach Typhoon Maysak on Wednesday.  The trough will produce southwesterly winds which will blow toward the top of the circulation.  Those winds will cause more vertical wind shear and the shear will cause Typhoon Maysak to weaken more quickly.

Typhoon Maysak will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Maysak toward the north during the next 24 hours.  On its anticipated track the core of Typhoon Maysak is likely to pass west of Kyushu.  Maysak could reach South Korea in about 18 hours.  Typhoon Maysak could be the equivalent of a large, major hurricane when it gets to South Korea.  Maysak will produce very strong winds over South Korea.  It will also drop heavy rain and flash floods could occur.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Haishen strengthened south of Iwo To.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Haishen was located at latitude 20.1°N and longitude 142.8°E which put it about 340 miles (545 km) south-southeast of Iwo To.  Haishen was moving toward the west-southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1000 mb.  Tropical Storm Haishen is forecast to strengthen into a typhoon and it could move toward western Japan later this week.

Tropical Storm Nana Forms South of Jamaica

Tropical Storm Nana formed over the Caribbean Sea south of Jamaica on Tuesday.  At 2:00 p.m. EDT on Tuesday the center of Tropical Storm Nana was located at latitude 16.7°N and longitude 78.4°W which put it about 110 miles (175 km) south of Negril, Jamaica.  Nana was moving toward the west at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

A Tropical Storm Watch was issued for the entire coast of Belize.  A Tropical Storm Watch was also issued for the north coast of Honduras from Punta Patuca to the border with Guatemala including Roatan Island and the Bay Islands.

An Air Force Reserve Hurricane Hunter flight into a low pressure system south of Jamaica found a defined low level center of circulation and winds to tropical storm force on Tuesday.  Based on data from the reconnaissance aircraft the National Hurricane Center designated the system Tropical Storm Nana.  The circulation around Tropical Storm Nana was organizing quickly.  Thunderstorms were developing near the center of circulation.  Bands of showers and thunderstorms were revolving around the center.  Storms near the center began to generate upper level divergence which was pumping mass away from the tropical storm.  The strongest winds were occurring in the northern half of the circulation.  Winds to tropical storm force extended out 80 miles (130 km) from the center of Nana.

Tropical Storm Nana will move through an environment favorable for intensification during the next 36 hours.  Nana will move over water where the Sea Surface Temperature is near 29.5°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Nana will continue to intensify and it is likely to strengthen to a hurricane within 36 hours.

Tropical Storm Nana will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Nana toward the west during the next day or two.  On its anticipated track the center of Tropical Storm Nana will pass north of Honduras on Wednesday.  Nana could reach Belize on Thursday and it is likely to be a hurricane by that time.

Elsewhere over the Atlantic Ocean, Tropical Depression Fifteen moved away from the East Coast of the U.S.  At 11:00 a.m. EDT on Tuesday the center of Tropical Depression Fifteen was located at latitude 34.7°N and longitude 73.1°W which put it about 140 miles (225 km) east-southeast of Cape Hatteras, North Carolina.  The depression was moving toward the east-northeast at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1008 mb.

Typhoon Maysak Brings Wind and Rain to the Ryukyu Islands

Typhoon Maysak brought winds and rain to the Ryukyu Islands on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Maysak was located at latitude 27.5°N and longitude 126.5°E which put it about 110 miles (175 km) west-northwest of Kadena AFB, Okinawa.  Maysak was moving toward the north-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 932 mb.

The eye and eyewall of Typhoon Maysak passed west of Okinawa on Monday.  Rainbands on the eastern side of Maysak passed over Okinawa and some of the other southern Ryukyu Islands.  A weather station at Naha reported a sustained wind speed of 58 m.p.h. (93 km/h).  A station at Kitahari (Kumejima Airport), which was closer to the center of Typhoon Maysak reported a sustained wind speed of 89 m.p.h. (144 km/h).

Satellite and radar images suggest that concentric eyewalls may have formed at the core of Typhoon Maysak.  The inner eye had a diameter of 8 miles (13 km).  A much larger outer eye with a diameter of approximately 100 miles (160 km) surrounded the inner eye.  Bands of showers and thunderstorms were revolving around the large core of Maysak.  Storms near the core were generating upper level divergence which was pumping mass away from the typhoon.

The circulation around Typhoon Maysak was large.  Winds to typhoon force extended out 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extended out 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maysak was 25.1.  The Hurricane Size Index (HSI) was 25.5 and the Hurricane Wind Intensity Size Index (HWISI).  Maysak was capable of causing widespread major damage.

Typhoon Maysak will move through an environment capable of supporting a strong typhoon during the next 24 hours, but it has likely reached its peak intensity.  The formation of concentric eyewalls normally results in a weaker, but larger tropical cyclone.  The wind speed will decrease when the inner eyewall dissipates.  When that occurs, the maximum wind speeds will occur in the larger outer eyewall.  Since Maysak will move over water where the Sea Surface Temperature is near 29°C, it will remain a typhoon for another 24 to 36 hours.

Typhoon Maysak will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Maysak toward the north during the next 36 hours.  On its anticipated track the center of Typhoon Maysak will pass west of Kyushu.  Typhoon Maysak could reach South Korea in 36 hours

Elsewhere over the Western North Pacific Ocean, Tropical Depression 11W was passing southeast of Iwo To.  At 11:00 p.m. EDT on Monday the center of Tropical Depression 11W was located at latitude 21.7°N and longitude 144.2°E which put it about 290 miles (470 km) southeast of Iwo To.  The depression was moving toward the west-southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1006 mb.

Tropical Depression Fifteen Forms South of Cape Hatteras

Tropical Depression Fifteen formed south of Cape Hatteras on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Tropical Depression Fifteen was located at latitude 32.6°N and longitude 76.5°W which put it about 190 miles (305 km) south-southwest of Cape Hatteras, North Carolina.  The depression was moving toward the northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1009 mb.

An Air Force Reserve Hurricane Hunters’ reconnaissance flight found that there was a closed low level circulation in a low pressure system south of Cape Hatteras and the National Hurricane Center designated the system as Tropical Depression Fifteen.  The circulation around Tropical Depression Fifteen was still organizing.  Bands of showers and thunderstorms were revolving around the low level center of circulation.  Storms near the center started to generate upper level divergence which pumped mass away to the east of the tropical depression.

Tropical Depression Fifteen will move through an environment somewhat favorable for intensification during the next day or two.  The depression will move over water where the Sea Surface Temperature is near 28.5°C.  It will move near the southern periphery of the upper level westerly winds in the middle latitudes.  Those winds will blow toward the top of the depression and they will cause moderate vertical wind shear.  The shear will inhibit intensification, but it will not be enough to prevent the depression from strengthening.  Tropical Depression Fifteen will likely strengthen into a tropical storm.

Tropical Depression Fifteen will move around the northern side of a subtropical high pressure system over the Atlantic Ocean.  The high will steer the depression toward the east-northeast during the next several days.  On its anticipated track the depression will move away from the U.S. and it will pass north of Bermuda.

Typhoon Maysak Strengthens to Equivalent of Major Hurricane Near Okinawa

Typhoon Maysak strengthened to the equivalent of a major hurricane near Okinawa on Monday.  At 11:00 a.m. EDT on Monday the center of Typhoon Maysak was located at latitude 25.5°N and longitude 127.0°E which put it about 110 miles (180 km) south-southwest of Kadena AFB, Okinawa.  Maysak was moving toward the north-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 936 mb.

Typhoon Maysak strengthened to the equivalent of a major hurricane on Monday as it approached Okinawa.  A circular eye with a diameter of 30 miles (50 km) was at the center of Maysak.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Maysak.  Storms near the core were generating upper level divergence which was pumping mass away from the typhoon.

Typhoon Maysak had a large circulation.  Winds to typhoon force extended out 70 miles (110 km) from the center of Maysak.  Winds to tropical storm force extended out 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maysak was 23.6.  The Hurricane Size Index (HSI) was 24.1 and the Hurricane Wind Intensity Size Index (HWISI) was 47.7.  Typhoon Maysak was capable of causing widespread major damage.

Typhoon Maysak will move through an environment favorable for intensification during the next 12 to 24 hours.  Maysak will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Maysak could strengthen further and it could intensify into the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

Typhoon Maysak will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Maysak toward the north during the next several days.  On its anticipated track the center of Typhoon Maysak will pass west of Okinawa during the next few hours.  Maysak will bring strong winds and heavy rain to Okinawa.  Typhoon Maysak could approach South Korea in about 48 hours.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 11W formed east-southeast of Iwo To.  At 11:00 a.m. EDT on Monday the center of Tropical Depression 11W was located at latitude 25.5°N and longitude 127.0°E which put it about 315 miles (515 km) east-southeast of Iwo To.  the depression was moving toward the southwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1008 mb.

Maysak Intensifies into a Typhoon East of Luzon

Former Tropical Storm Maysak intensified into a typhoon on Saturday.  At 5:00 p.m. EDT on Saturday the center of Typhoon Maysak was located at latitude 17.2°N and longitude 128.7°E which put it about 335 miles (540 km) east of Luzon.  Maysak was moving toward the west-northwest at 4 m.p.h. (6 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 976 mb.

The circulation around Typhoon Maysak exhibited greater organization on Saturday.  The inner end of a rainband wrapped partially around the center of circulation and an eye could be forming at the center of Maysak.  Bands of showers and thunderstorms were revolving around the core of Maysak.  Storms near the core were generating upper level divergence which was pumping mass away from the core.  Winds to typhoon force extended out 30 miles (50 km) from the center of circulation.  Winds to tropical storm force extended out 185 miles (295 km) from the center.

Typhoon Maysak will move through an environment favorable for intensification during the next 36 to 48 hours.  Maysak will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds will be weak and there will be little vertical wind shear.  Typhoon Maysak will continue to strengthen and it could intensify rapidly when an eye and eyewall are fully formed.  Maysak could strengthen into the equivalent of a major hurricane within 24 to 36 hours.

Typhoon Maysak will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Maysak toward the north during the next several days.  On its anticipated track Typhoon Maysak will move toward the southern Ryukyu Islands.  Maysak could pass near Okinawa in about 48 hours.  Typhoon Maysak is likely to be the equivalent of a major hurricane when it passes near Okinawa.

Tropical Storm Maysak Forms East of Luzon

Tropical Storm Maysak formed east of Luzon on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Maysak was located at latitude 16.4°N and longitude 129.4°E which put it about 435 miles (700 km) east of Luzon.  Maysak was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 997 mb.

More thunderstorms developed near the center of a low pressure system east of Luzon on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Maysak.  Thunderstorms were also forming in bands revolving around the center of Maysak.  Storm nears the center were generating upper level divergence which was pumping mass away from the tropical storm.  Winds to tropical storm force extended out 140 miles (225 km) from the center of circulation.

Tropical Storm Maysak will move through an environment favorable for intensification during the next 48 hours.  Maysak will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Maysak will intensify quickly and it could strengthen into a typhoon within 24 hours.  Once an inner core with an eye and an eyewall is established Maysak could rapidly intensify into the equivalent of a major hurricane.

Tropical Storm Maysak will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Maysak toward the north-northwest.  On its anticipated track Tropical Storm Maysak could approach the Ryukyu Islands within 72 hours.  Maysak could be the equivalent of a major hurricane by that time.

Laura Weakens to Tropical Storm over Arkansas

Former Hurricane Laura weakened to a tropical storm over Arkansas on Thursday afternoon.  At 2:00 p.m. EDT on Thursday the center of Tropical Storm Laura was located at latitude 32.9°N and longitude 92.8°W which put it about 25 miles (40 km) west-southwest of El Dorado, Arkansas.  Laura was moving toward the north-northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 988 mb.

All coastal Tropical Storm Warnings have been discontinued.

Hurricane Laura caused significant wind damage over southwestern Louisiana.  The largest concentration of damage appeared to be around Lake Charles, Louisiana.  There were reports that the dome for the weather radar at the National Weather Service office in Lake Charles sustained heavy damage.  The Automated Surface Observing Station (ASOS) at Lake Charles reported a peak wind speed of 133 m.p.h. (215 km/h).  There were also reports of widespread power outages in Louisiana and eastern Texas.

Former Hurricane Laura gradually weakened as it moved inland over Louisiana.  The circulation around Tropical Storm Laura was still well organized.  However, drier air was wrapping around the western and southern sides of the circulation.  The heavier rains and stronger winds were north and east of the center of Laura.  Flash Flood Watches were in effect for parts of Arkansas, western Tennessee, western Kentucky and extreme southeastern Missouri.

Tropical Storm Laura will turn more toward the east when it reaches southern Missouri on Friday.  Westerly winds in the middle latitudes will carry Laura toward the east coast of the U.S.  Tropical Storm Laura could bring gusty winds and locally heavy rain to West Virginia on Saturday.

Tropical Storms Hernan and Iselle Form West of Mexico

Tropical Storms Hernan and Iselle formed west of Mexico.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Hernan was located at latitude 19.1°N and longitude 106.2°W which put it about 95 miles (155 km) south-southwest of Cabo Corrientes, Mexico.  Hernan was moving toward the north-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

The circulation around Tropical Storm Hernan was not well organized.  An upper level ridge over the southwestern U.S. and northern Mexico was producing northeasterly winds which were blowing toward the top of Hernan.  Those winds were causing strong vertical wind shear.  As a result of the shear, the stronger thunderstorms were occurring in bands in the southern part of the circulation.  Bands in the other parts of Tropical Storm Hernan consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out 100 miles in the southern half of Hernan.  Winds in the northern half of the circulation were blowing at less than tropical storm force.

Tropical Storm Hernan will move through an environment unfavorable for intensification during the next several days.  Hernan will move over water where the Sea Surface Temperature is near 29°C.  So, there will be plenty of energy in the upper ocean to support intensification.  However, the upper level ridge will continue to cause strong vertical wind shear, which will inhibit potential intensification.  Tropical Storm Hernan is likely to weaken on Friday when it moves over colder water.  Hernan could approach the southern end of Baja California on Friday.

At 11:00 a.m. EDT on Thursday the center of Tropical Storm Iselle was located at latitude 17.0°N and longitude 115.8°W which put it about 560 miles (900 km) southwest of the southern tip of Baja California.  Iselles was moving toward the northeast at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

The circulation around Tropical Storm Iselle was also not well organized.  It was being sheared by the same upper level ridge that was causing strong vertical wind shear over Tropical Storm Hernan.  Most of the thunderstorms in Iselle were also occurring in the southern half of the circulation.  Tropical storm force winds extended out 100 miles from the center in the southern half of Tropical Storm Iselle.  Iselle will also move through an environment unfavorable for intensification.

Powerful Hurricane Laura Makes Landfall in Southwest Louisiana

Powerful Hurricane Laura made landfall in southwest Louisiana on Wednesday night.  At 2:00 a.m. EDT on Thursday the center of Hurricane Laura was located at latitude 29.8°N and longitude 93.3°W which put it about 30 miles (50 km) south-southwest of Lake Charles, Louisiana.  Laura was moving toward the north at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 938 mb.

A Hurricane Warning was in effect for the portion of the coast from High Island, Texas to Intracoastal City, Louisiana.  Tropical Storm Warnings were in effect for the portions of the coast from San Luis Pass to High Island, Texas and from Intracoastal City to the Mouth of the Mississippi River.

The center of Hurricane Laura officially made landfall near Cameron, Louisiana on Tuesday night.  Hurricane Laura was the strongest hurricane on record to make landfall on the coast of southwest Louisiana.  Laura was stronger than Hurricane Rita was when Rita made landfall in the same area in September 2005.  The Hurricane Intensity Index (HII) for Hurricane Laura was 31.6.  The Hurricane Size Index (HSI) was 19.6 and the Hurricane Wind Intensity Size Index (HWISI) was 51.2.  Hurricane Laura was capable of causing widespread extensive damage.

A NOAA National Ocean Service weather station at Calcasieu Pass measured a sustained wind speed of 93 m.p.h. (150 km/h) and a wind gust of 127 m.p.h. (204 km/h) during the passage of the northern eyewall.  The station also recorded a water rise of over 10 feet (3 meters).  The National Weather Service station at the Lake Charles airport measured a wind gust of 104 m.p.h. (167 km/h) during the passage of an inner rainband.  There were numerous reports of power outages.

Hurricane Laura will move inland over western Louisiana on Thursday.  The center of Laura will move over southern Arkansas by Thursday night.  Hurricane Laura will continue to cause a significant storm surge along the coast of Louisiana on Thursday morning.  Laura could produce hurricane force winds in Alexandria, Louisiana.  It could bring strong tropical storm force winds to Shreveport and Monroe.  Hurricane Laura will also drop heavy rain over Louisiana and parts of Arkansas.  Flash floods could occur in some locations.