Category Archives: Tropical Cyclones

Information about tropical cyclones

Typhoon Jebi Intensifies Rapidly East of Northern Marianas

Typhoon Jebi intensified rapidly east of the Northern Marianas on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Typhoon Jebi was located at latitude 17.5°N and longitude 149.8°E which put it about 270 miles (435 km) east of Pagan.  Jebi was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 959 mb.  A Typhoon Warning was in effect for Agrihan, Pagan and Alamagan in the Northern Marianas.

The circulation of Typhoon Jebi was very well organized and it was symmetrical.  A small circular eye formed at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of thunderstorms were revolving around the core of Typhoon Jebi.  Storms around the core were generating strong upper level divergence which was pumping large quantities of mass away from the typhoon.  Winds to typhoon force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) from the center.

Typhoon Jebi will be moving through an environment very favorable for further intensification.  Jebi will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Jebi is likely to intensify into the equivalent of a major hurricane on Thursday.

Typhoon Jebi will move south of a subtropical ridge over the Western North Pacific for several more days.  The ridge will steer Jebi in a general westerly direction during that time.  Typhoon Jebi will reach the western end of the ridge in about 48 hours.  Jebi will make a gradual turn toward the north when it reaches the end of the ridge.  On its anticipated track Typhoon Jebi will reach the northernmost Mariana Islands within 24 hours.  Jebi will be capable of causing major damage when it arrives.  Jebi is forecast to pass south of Iwo To, but it will turn toward the major islands of Japan during the weekend.

Miriam and Norman Become Hurricanes

Both former Tropical Storm Miriam and Tropical Storm Norman strengthened into hurricanes over the Eastern North Pacific on Wednesday afternoon.  At 5:00 p.m. EDT on Wednesday the center of Hurricane Miriam was located at latitude 14.0°N and longitude 139.7°W which put it about 1090 miles east of Hilo, Hawaii.  Miriam was moving toward the west at 9 m.p.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 992 mb.

At 5:00 p.m. EDT on Wednesday the center of Hurricane Norman was located at latitude 17.6°N and longitude 116.9°W which put it about 545 miles (875 km) southwest of the southern tip of Baja California.  Norman was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts t0 90 m.p.h. (145 km/h).  The minimum surface pressure was 987 mb.

An inner rainband wrapped much of the way around the center of circulation and an eye developed at the center  of Hurricane Miriam on Wednesday.  Storms near the core of Miriam generated strong upper level divergence which pumped mass away from the hurricane.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  The strongest rainbands were south and east of the center of Hurricane Miriam.  Rainbands on the northwest side of the circulation contained more showers and low clouds.

An inner rainband also wrapped most of the way around the center of Hurricane Norman on Wednesday and an eye appeared to be forming at the center of circulation.  Several bands of showers and thunderstorms were revolving around the core of Norman.  The distribution of thunderstorms in Norman was more symmetrical.  Storms around the core of Hurricane Norman were generating well developed upper level divergence.

Both Hurricane Miriam and Hurricane Norman were moving south of a subtropical ridge over the Eastern North Pacific Ocean.  Miriam could reach the end of the ridge in the next day or two and turn toward the north.  The ridge is forecast to steer Hurricane Norman westward during the next two or three days.

Hurricane Miriam will approach an upper level trough east of Hawaii.  The trough will produce southwesterly winds which will increase vertical wind shear.  The shear is forecast to cause Miriam to weaken.  Hurricane Norman will move over water where the Sea Surface Temperature is near 28°C.  Norman will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Norman is forecast to intensify into a major hurricane.

Tropical Storm Norman Forms Southwest of Baja California

Tropical Storm Norman formed southwest of Baja California on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Norman was located at latitude 17.5°N and longitude 113.9°W which put it about 455 miles (730 km) southwest of the southern tip of Baja California.  Norman was moving toward west-northwest at 10 m.p.h. (16 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.

The circulation of Tropical Storm Norman organized quickly on Wednesday.  A distinct low level center of circulation developed in an area of thunderstorms southwest of Baja California and the National Hurricane Center designated the system as Tropical Storm Norman.  A primary rainband wrapped part of the way around the center of circulation.  Several other bands of showers and thunderstorms formed and began to revolve around the core of Norman.  Storms near the core started to generate strong upper level divergence which was pumping mass away from the tropical storm in all directions.

Tropical Storm Norman will be moving through an environment favorable for intensification during the next several days.  Norman will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Norman could intensify to a hurricane in the next 24 hours.  Once an eye forms and the inner core is full organized, Norman could intensify rapidly.  It could strengthen into a major hurricane later this week.

Tropical Storm Norman will move south of a subtropical ridge over the Eastern North Pacific during the next few days.  The ridge will steer Norman in a general westerly direction.  On its anticipated track Tropical Storm Norman will move toward the Central Pacific.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Miriam continued to move westward.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Miriam was located at latitude 14.1°N and longitude 137.4°W which put it about 1230 miles (1980 km) east of HIlo, Hawaii.  Miriam 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 1000 mb.

Tropical Storm Jebi Forms East of the Marianas

Tropical Storm Jebi formed east of the Marianas on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Jebi was located at latitude 15.8°N and longitude 156.6°E which put it about 745 miles (1200 km) east of Saipan.  Jebi was moving toward the northwest at 17 m.p.h. (28 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 1004 mb.

A distinct low level center of circulation developed in a cluster of showers and thunderstorms east of the Northern Marianas and the Japan Meteorological Agency designated the system as Tropical Storm Jebi.  The circulation of Jebi was still organizing.  A primary rainband wrapped around the eastern and northern sides of the center of circulation.  Other bands of showers and thunderstorms were developing in the eastern half of the circulation.  Storms near the center started to generate upper level divergence.

Tropical Storm Jebi will move through an environment favorable for intensification during the next several days.  Jebi will move over water where the Sea Surface Temperature is near 29°C.  It will move under the western end of an upper level ridge.  The ridge will produce southerly winds which will cause some vertical wind shear.  Two upper level lows northwest and northeast of Jebi will enhance upper level divergence to the north of the tropical storm.  Tropical Storm Jebi will strengthen and it could become a typhoon later this week.

Tropical Storm Jebi will move southwest of a ridge over the Western North Pacific Ocean.  The ridge is forecast to strengthen and it will steer Jebi in a general west-northwesterly direction during the next several days.  On its anticipated track Tropical Storm Jebi could be near the northernmost Mariana Islands in about three days.  Jebi could be a typhoon by that time.  Jebi could be south of Iwo To by the end of the week.

Tropical Storm Miriam Forms Southwest of Baja California

Tropical Storm Miriam formed southwest of Baja California on Sunday morning.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Miriam was located at latitude 13.2°N and longitude 125.3°W which put it about 1210 miles (1950 km) west-southwest of the southern tip of Baja California.  Miriam was moving toward the west at 13 m.p.h. (20 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 1004 mb.

The circulation of Tropical Storm Miriam organized quickly on Sunday morning.  Several bands of showers and thunderstorms developed and the bands began to revolve around the center of circulation.  Storms near the core of Miriam started to generate upper level divergence which was pumping mass away in all directions.

Tropical Storm Miriam will move through an environment favorable for intensification during the next several days.  Miriam will move over water where the Sea Surface Temperature is near 28°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Miriam could intensify into a hurricane on Monday.  Miriam could intensify rapidly once the inner core becomes fully organized and an eye develops at the center of circulation.

Tropical Storm Miriam will move south of the subtropical ridge over the Eastern North Pacific Ocean.  The ridge will steer Miriam in a general westerly direction during the next two or three days.  On its anticipated track Tropical Storm Miriam will move farther away from Baja California.

Weakening Tropical Storm Lane Moves Away from Hawaii

A weakening Tropical Storm Lane moved away from Hawaii on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Lane was located at latitude 19.5°N and longitude 160.2°W which put it about 195 miles (310 km) southwest of Honolulu, Hawaii.  Lane was moving toward the west at 9 m.p.h. (15 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 998 mb.  All Tropical Storm Warnings and Watches for the Hawaiian Islands have been discontinued.

An upper level trough west of the Hawaiian Islands produced strong southwesterly winds which blew the upper portion of the circulation of former Hurricane Lane off the lower part of the circulation.  Tropical Storm Lane consisted primarily of a well develop low level circulation of bands of showers and lower clouds.  A few thunderstorms continued to develop in outer bands on the eastern side of the circulation.

Since Tropical Storm Lane exists primarily in the lower levels of the atmosphere, it is being steered westward by a subtropical ridge over the Central Pacific Ocean.  A general westerly motion is forecast during the next several days.  The upper level trough will continue to cause strong vertical wind shear and Tropical Storm Lane will continue to weaken.

Hurricane Lane Edges Closer to Hawaii

Hurricane Lane edged closer to Hawaii on Friday.  At 5:00 p.m. EDT on Friday the center of Hurricane Lane was located at latitude 19.1°N and longitude 157.9°W which put it about 150 miles (245 km) south of Honolulu, Hawaii.  Lane was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 966 mb.

Hurricane Warnings were in effect for Oahu and Maui County including the islands of Maui, Lanai, Molokai and Kahoolawe.  A Tropical Storm Warning was in effect for Hawaii County.  A Tropical Storm Watch was in effect for Kauai County including Kauai and Niihau.  Flash Flood Watches were in effect for all Hawaiian Islands.

Hurricane Lane weakened gradually on Friday.  There was no longer an eye at the center of circulation.  The strongest thunderstorms were occurring in  a band northwest of the center.  The strongest winds and heaviest rain were occurring in that band of storms.  Other rainbands in the northern half of the circulation were revolving around the center of Hurricane Lane.  The bands in the southern half of the circulation were weaker and they consisted primarily of showers and lower clouds.  Winds to hurricane force extended out about 35 miles from the center of circulation, primarily on the northern side of Lane.  Winds to tropical storm force extended out about 140 miles (225 km) from the center.

Hurricane Lane will continue to weaken on Saturday.  An upper level trough west of the Hawaiian Islands is producing strong southwesterly winds which were causing significant vertical wind shear.  Those winds were tilting the circulation toward the northeast and they were inhibiting upper level divergence to the west of the hurricane.  The slow movement of Hurricane Lane is allowing the wind to mix cooler water to the surface of the ocean.  Significant vertical wind shear and cooler water will cause Lane to weaken.  If the upper level winds become strong enough, there is the chance that they could blow the upper part of the circulation away from the lower level circulation.

The upper level trough will push Hurricane Lane slowly toward the north during the next 12 to 24 hours.  On its anticipated track Hurricane Lane will get closer to Maui and Oahu.  When most of the stronger, taller thunderstorms weaken, then Lane will be steered more by the winds in the lower levels of the atmosphere.  Those winds are blowing from east to west and they are forecast to Lane toward the west just before the center reaches Oahu and Maui.  Although Hurricane Lane will cause gusty winds, locally heavy rain and flash floods are the greatest risks.  Heavy rain has already fallen on the Big Island of Hawaii and Flash Flood Watches have been issued for all of the Hawaiian Islands.

Hurricane Lane Drops Heavy Rain on Hawaii

Hurricane Lane dropped heavy rain on Hawaii on Thursday.  The airport in Hilo, Hawaii reported 14.02 inches (356 mm) of rain during the past 24 hours.  At 11:00 p.m. EDT Thursday the center of Hurricane Lane was located at latitude 17.8°N and longitude 157.9°W which put it about 240 miles (390 km) south of Honolulu, Hawaii.  Lane was moving toward the north-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 959 mb.

Hurricane Warnings were in effect for Oahu and Maui County including the islands of Maui, Lanai, Molokai and Kahoolawe.  A Hurricane Watch was in effect for Kauai County including the islands of Kauai and Niihau.  A Tropical Storm Warning was in effect for Hawaii County.

Hurricane Lane began to weaken on Thursday.  An upper level trough west of Hawaii was producing southwesterly winds which were blowing toward the top of the hurricane.  Those winds were causing moderate vertical wind shear and they were obstructing upper level divergence to the west of Hurricane Lane.  The wind shear prevented the circulation from pumping as much mass away from the hurricane and the surface pressure began to increase.

Hurricane Lane retained a strong circulation in spite of increased vertical wind shear.  Winds to hurricane force extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out 125 miles (205 km) from the center.  The core of Hurricane Lane passed over NOAA buoy 51002.  The strongest winds occurred in the northern eyewall.  The buoy measured a sustained wind speed of 83 m.p.h. (133 km/h).  It also reported a wind gust to 105 m.p.h. (170 km/h).  The winds were significantly weaker in the southern half of the circulation.

The upper level trough gradually turned Hurricane Lane more toward the north on Thursday.  A general motion toward the north is forecast for Friday.  On its anticipated track Hurricane Lane could approach Maui and Oahu on Friday night.  Lane is forecast to weaken further during the next 24 hours.  Guidance from numerical models suggests that the weaker circulation will be steered by winds in the lower levels when it nears Maui and Oahu.  The models are forecasting a turn toward the west.  Hurricane Lane could cause gusty winds and power outages.  The greater risk will be caused by the locally heavy rain, which will create the potential for flash floods.  Flash floods may develop very quickly in areas of steep terrain.

Typhoon Cimaron Brings Wind and Rain to Japan

Typhoon Cimaron brought wind and rain to Japan on Thursday.  At 2:00 p.m. EDT on Thursday the center of Typhoon Cimaron was located at latitude 35.9°N and longitude 135.1°E which put it about 70 miles west of Fukui, Japan.  Cimaron was moving toward the north at 26 m.p.h. (42 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 979 mb.

The center of Typhoon Cimaron moved near the eastern end of Shikoku early on Wednesday.  Cimaron moved quickly northward and the center passed over Awaji Island.  Typhoon Cimaron made landfall on Honshu west of Kobe and Osaka near Akashi.  Cimaron continued to move quickly toward the north across Honshu and the center of circulation emerged over the Sea of Japan later on Thursday.  Kansai International Airport reported a sustained wind speed of 65 m.p.h. (105 km/h).  Komoda, Japan reported a sustained wind speed of 63 m.p.h. (102 km/h).

Typhoon Cimaron dropped locally heavy rain over parts of Shikoku and southwestern Honshu.  Kobe measured 4.75 inches (120.5 mm) of rain and there could have been higher amounts in mountainous regions where the wind was blowing up the slopes.  The potential for flash floods exists in areas of steep terrain.

Typhoon Cimaron is forecast to weaken over the Sea of Japan.  It will move over cooler water.  In addition, an upper level trough over eastern Asia will produce strong westerly winds that will cause significant vertical wind shear.  The trough is forecast to turn Typhoon Lane toward the east and it could make another landfall over northern Honshu or Hokkaido.  Cimaron will weaken to a tropical storm, but it could drop heavy rain over those areas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Soulik was making landfall on the southwestern coast of South Korea near Mokp’o.  At 11:00 a.m. EDT on Thursday the center of Tropical Soulik was located at latitude 35.2°N and longitude 126.8°E which put it about 90 miles (145 km) south-southwest of Kunsan, South Korea.  Soulik was moving toward the north-northeast at 14 m.p.h. (22 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 985 mb.

The upper level trough over eastern Asia was also causing strong vertical wind shear over Tropical Storm Soulik.  Soulik was weakening as it approached the coast, but it will still be capable of dropping locally heavy rain over portions of South Korea.  The heavy rain could create the potential for flash floods.

Hurricane Lane Turns Northwest, Warning Issued for Oahu

Hurricane Lane turned toward the northwest on Wednesday night and a Hurricane Warning was issued for Oahu.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Lane was located at latitude 15.9°N and longitude 156.5°W which put it about 385 miles (620 km) south-southeast of Honolulu, Hawaii.  Lane was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 939 mb.

Hurricane Warnings were in effect for Oahu, Hawaii County and Maui County including the islands of Maui, Lanai, Molokai and Kahoolawe.  Hurricane Watches were in effect for Kauai County including Kauai and Nihhau.

Hurricane Lane weakened slightly on Wednesday but it remained a powerful hurricane.  There was a small eye at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Lane.  Winds to hurricane force extended out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out about 140 miles (225 km) from the center.

The environment around Hurricane Lane will gradually become less favorable for a powerful hurricane.  Lane will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough west of Hawaii will produce southwesterly winds which will cause more vertical wind shear.  Hurricane Lane will gradually weaken, but it could remain a major hurricane for another 36 hours.

The upper level trough will turn Hurricane Lane more toward the north-northwest.  On its anticipated track the center of Hurricane Lane will move closer to Hawaii.  The center of Lane will be southwest of the Big Island of Hawaii in about 24 hours.  The center of Lane could be south of Oahu on Friday.  Even if the center of Hurricane Lane does not pass over any of the islands, wind blowing up the slopes of the mountains will contribute to locally heavy rain and the potential for flash floods.