Category Archives: Tropical Cyclones

Information about tropical cyclones

Major Hurricane Sergio Churns Southwest of Baja California

Major Hurricane Sergio churned southwest of Baja California.  At 5:00 p.m. EDT on Wednesday the center of Hurricane Sergio was located at latitude 13.3°N and longitude 117.9°W which put it about 845 miles (1360 km) southwest of the southern tip of Baja California.  Sergio was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 145 m.p.h. (230 km/h).  The minimum surface pressure was 955 mb.

Hurricane Sergio is a well organized hurricane.  There is a circular eye at the center of circulation.  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Hurricane Sergio.  Storms near the core are generating strong upper level divergence which is pumping mass away in all directions from the hurricane.

Winds to hurricane force extend out about 45 miles (75 km) from the center of Hurricane Sergio.  Winds to tropical storm force extend out about 150 miles (240 km) from the center of circulation.  The Hurricane intensity Index (HII) for Hurricane Sergio is 23.6.  The Hurrricane Size Index (HSI) is 15.1 and the Hurricane Wind Intensity Size Index (HWISI) is 38.7.

Hurricane Sergio will remain in an environment capable of supporting a major hurricane for several more days.  Sergio 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.  Hurricane Sergio could strengthen to Category 4 on the Saffir-Simpson Scale.  Hurricane Sergio will move over cooler water in a couple of days and it is likely to weaken when that occurs.

Hurricane Sergio will move south of a subtropical ridge over the Eastern North Pacific Ocean.  The ridge will steer Sergio toward the northwest during the next day or so.  The ridge is forecast to strengthen on Friday and it will steer Sergio more toward the west when that happens.  On its expected track Hurricane Sergio will move gradually farther away from Baja California.

Leslie Strengthens Into a Hurricane East of Bermuda

Former Tropical Storm Leslie strengthened into a hurricane east of Bermuda on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Hurricane Leslie was located at latitude 29.5°N and longitude 56.8°W which put it about 510 miles (825 km) east-southeast of Bermuda.  Leslie was nearly stationary.  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 975 mb.

After being designated as a subtropical storm, Hurricane Leslie made a transition to an extratropical cyclone and then back to a subtropical storm.  Leslie eventually moved over warmer water and the structure changed to that of a tropical storm, which intensified slowly until it reached hurricane intensity earlier this morning.  It is gradually exhibiting the classical appearance and structure of a hurricane.

There is a circular eye at the center of circulation.  A nearly complete ring of thunderstorms surrounds the eye and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Hurricane Leslie.  Storms near the core are generating upper level divergence which is pumping mass away from the hurricane, which is causing the surface pressure to decrease.  Winds to hurricane force extend out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extend out about 230 miles (370 km) from the center.

Hurricane Leslie will remain in an environment favorable for intensification for another day or two.  Leslie will remain over water where the Sea Surface Temperature is near 27.5°C.  it will be in a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Leslie is likely to get a little stronger during the next day or so.  Leslie will move over cooler water later this week and it will start to weaken when that happens.

Hurricane Leslie has been in an area where the steering winds were weak which is why it has meandered east of Bermuda during the past few days.  A subtropical ridge southeast of Leslie will strengthen during the next day or two and the ridge will start to steer the hurricane toward the north.  On its anticipated track Hurricane Leslie will move farther away from Bermuda later this week.

Typhoon Kong-rey Quickly Strengthens Into Equivalent of Cat. 5 Hurricane

Typhoon Kong-rey quickly strengthened into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Kong-rey was located at latitude 17.9°N and longitude 137.3°E which put it about 690 miles (1110 km) southeast of Okinawa.  Kong-rey was moving toward the west-northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 910 mb.

The circulation of Typhoon Kong-rey was very organized and symmetrical.  There was a circular eye at the center of Kong-rey.  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 Typhoon Kong-rey.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.

Kong-rey is a large typhoon.  Winds to typhoon force extend out about 75 miles (120 km) from the center of circulation.  Winds to tropical storm force extend out about 240 miles (390 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Kong-rey is 35.0.  The Hurricane Size Index (HSI) is 26.8 and the Hurricane Wind Intensity Size Index (HWISI) is 61.8.  Typhoon Kong-rey is capable of causing widespread catastrophic damage.

Typhoon Kong-rey will remain in an environment very favorable for strong typhoons for another 24 to 36 hours.  Kong-rey 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.  If a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Typhoon Kong-rey to weaken.  An upper level trough near Taiwan will produce southwesterly winds which will cause the vertical wind shear to increase in a couple of days.  Kong-rey will weaken more steadily when the wind shear increases.

Typhoon Kong-rey will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Kong-rey toward the northwest for several more days.  On its anticipated track Typhoon Kong-rey could approach the Rykyu Islands in 48 to 60 hours.  It will still be a typhoon at that time.  If Typhoon Kong-rey brings strong winds and heavy rain, it will hamper the recovery from Typhoon Trami which hit the Ryukyu Islands a few days ago.

Hurricane Walaka Rapidly Intensifies to Category 5

Hurricane Walaka rapidly intensified to Category 5 on the Saffir-Simpson Scale on Monday.  At 11:00 p.m. EDT on Monday the center of Hurricane Walaka was located at latitude 13.2°N and longitude 169.8°W which put it about 240 miles (390 km) south of Johnston Atoll.  Walaka was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 920 mb.

A Hurricane Warning is in effect for Johnston Atoll.  A Hurricane Watch is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals to Maro Reef.

The circulation of Hurricane Walaka is very well organized,  There is a circular eye at the center of Walaka.  The eye is 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 Walaka.  Storms near the core were generating strong upper level divergence which was pumping mass away from the hurricane in all directions.

Winds to hurricane force extended out about 50 miles (80 km) from the center of Hurricane Walaka.  Winds to tropical storm force extended out about 185 miles (300 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Walaka was 35.0.  The Hurricane Size Index (HSI) was 16.4 and the Hurricane Wind Intensity Size Index (HWISI) was 51.4.

Hurricane Walaka will remain in an environment very favorable for strong hurricanes for several more days.  Walaka 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.  If a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Hurricane Walaka to weaken.  In several days Walaka will move into an area where the upper level winds are stronger and the vertical wind shear will increase.  Hurricane Walaka will weaken more quickly when the shear increases.

Hurricane Walaka is moving around the western end of a subtropical high pressure system.  The high pressure system will steer Walaka toward the north during the next several days.  On its anticipated track Hurricane Walaka will pass near Johnston Atoll on Tuesday.

Tropical Storm Rosa Nears Baja California

Tropical Storm Rosa moved nearer to Baja California on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Rosa was located at latitude 27.5°N and longitude 116.5°W which put it about 90 miles (145 km) west-southwest of Punta Eugenia, Mexico.  Rosa was moving toward the north-northeast at 12 m.p.h. (19 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 1000 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Abreojos to Cabo San Quintin, Mexico.  A Tropical Storm Watch was in effect for the portion of the coast from Bahia de los Angeles to San Felipe, Mexico.

Tropical Storm Rosa was weakening as it approached the coast of Baja California.  Rosa was moving over water where the Sea Surface Temperature was near 23°C.  An upper level low west of California was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing significant vertical wind shear.  The effects of cool water and vertical shear were causing most of the stronger thunderstorms to occur northeast of the center of circulation.  Bands south and west of the center consisted primarily of showers and lower clouds.

The center of Tropical Storm Rosa will reach northern Baja California in a few hours.  Rosa will bring some gusty winds when when it reaches the coast, but the greater risk is locally heavy rainfall.  Rosa could drop several inches of rain and flash floods could occur.  The lower level part of Rosa’s circulation will weaken when it crosses Baja California.  However, the upper low west of California will steer the middle and upper parts of Tropical Storm Rosa over the Southwestern U.S.  Rosa, or its remnants, could drop locally heavy rain over that region during the next several days.  Flash Flood Watches have been issued for southeastern California, eastern Nevada, western Arizona, and much of Utah.

Elsewhere over the Eastern North Pacific, Tropical Storm Sergio was strengthening slowly south of Baja California.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Sergio was located at latitude 11.5°N and longitude 109.5°W which put it about 790 miles (1275 km) south of the southern tip of Baja California.  Sergio was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 995 mb.

Large Typhoon Trami Brings Wind and Rain to Japan

Large Typhoon Trami brought wind and rain to Japan on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Typhoon Trami was located at latitude 31.8°N and longitude 132.3°E which put it about 140 miles (225 km) southwest of Kochi, Japan.  Trami was moving toward the northeast at 22 m.p.h. (33 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. (200 km/h).  The minimum surface pressure was 950 mb.

There was still a large eye at the center of Typhoon Trami, but the ring of thunderstorms around the eye was beginning to look a little more ragged.  However, the circulation around Trami was very large.  Winds to typhoon force extended out about 155 miles (250 km) from the center of circulation.  Winds to tropical storm force extended out about 355 miles (575 km) from the center.

The Hurricane Intensity Index (HII) for Typhoon Trami was 17.8.  The Hurricane Size Index (HSI) was 49.6 and the Hurricane Wind Intensity Size Index (HWISI) was 67.4.  Typhoon Trami was capable of causing extensive serious damage.

Typhoon Trami brought strong winds and heavy rain to Okinawa and the northern Ryukyu Islands on Saturday.  There were reports of damage.  The northern eyewall of Trami passed over Kyushu.  Strong winds and heavy rain were falling in that region.  Heavy rain and strong winds will reach Shikoku shortly.  The center of Typhoon Trami could be near Kyoto in about six hours.  Trami will move northeast across Honshu on Sunday.  It will bring heavy rain and gusty winds to much of Japan.  Flash flooding will be possible over much of Japan.

Elsewhere over the Western North Pacific Ocean Tropical Storm Kong-rey was strengthening southeast of the Ryukyu Islands.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Kong-rey was located at latitude 14.1°N and longitude 138.1°E which put it about 1165 miles (1880 km) east of Manila, Philippines.  Kong-rey was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 983 mb.

Hurricane Rosa Moves Toward Baja California

Hurricane Rosa moved toward Baja California on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Rosa was located at latitude 22.4°N and longitude 118.9°W which put it about 440 miles (710 km) south-southwest of Punta Eugenia, Mexico.  Rosa was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 969 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Abreojos to Cabo San Quintin, Mexico.  A Tropical Storm Watch was in effect for the portion of the coast from Bahia de los Angeles to San Felipe, Mexico.

Hurricane Rosa will move into an environment unfavorable for hurricanes on Sunday.  Rosa will move over water where the Sea Surface Temperature is cooler than 26°C.  In addition an upper level low near the west coast of the U.S. will produce southwesterly winds which will cause vertical wind shear.  The combination of cooler water and more vertical wind shear will cause Hurricane Rosa to weaken.  Rosa could weaken to a tropical storm by Sunday night.

The upper low will steer Hurricane Rosa toward the northeast during the next several days.  On its anticipated track Rosa could reach Baja California on Monday.  It will likely be a tropical storm at that time.  Even though it will weaken, Rosa will drop heavy rain over parts northern Baja California and the southwestern U.S.  The heavy rain could cause flash floods.

Elsewhere over the Eastern North Pacific Ocean Tropical Storm Sergio formed southwest of Acapulco, Mexico.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Sergio was located at latitude 12.3°N and longitude 103.3°W which put it about 390 miles (630 km) southwest of Acapulco, Mexico.  Sergio was moving toward the west at 10 m.p.h. (16 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 1003 mb.

Tropical Storm Walaka Forms South of Hawaii

Tropical Storm Walaka formed south of Hawaii on Saturday afternoon.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Walaka was located at latitude 11.5°N and longitude 159.1°W which put it about 680 miles (1095 km) south of Honolulu, Hawaii.  Walaka was moving toward the west at 15 m.p.h. (24 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 1005 mb.

A distinct low level center of circulation formed within an area of thunderstorms south of Hawaii on Saturday and the Central Pacific Hurricane Center designated the system as Tropical Storm Walaka.  The circulation around Walaka was still organizing.  Most of the thunderstorms were developing in bands south and east of the center of circulation.  Bands north and west of the center consisted primarily of showers and lower clouds.  Storms south and east of the center were beginning to generate upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Walaka will be moving through an environment that will be favorable for intensification.  Walaka 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 Walaka will strengthen into a hurricane and it could intensify rapidly once the inner core is well organized around an eye.

Tropical Storm Walaka will move south of a subtropical high pressure system over the Central Pacific Ocean during the next two or three days.  The ridge will steer Walaka in a general westward direction.  On its anticipated track Tropical Storm Walaka will remain south of Hawaii.

Large Typhoon Trami Nears Okinawa

Large Typhoon Trami neared Okinawa late on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Trami was located at latitude 25.1°N and longitude 126.9°E which put it about 135 miles (225 km) south-southwest of Okinawa.  Trami was moving toward the northwest at 6 m.p.h.  The maximum sustained wind speed was 105 m.p.h. (170 km) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 949 mb.

After completing an eyewall replacement cycle over a day ago that left it weaker, but larger, Typhoon Trami has been in a relatively steady state.  There is a very large eye with a diameter of almost 100 miles (160 km) at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the large eye.

The circulation around Typhoon Trami is large.  Winds to typhoon force extend out about 75 miles (120 km) from the center of circulation.  Winds to tropical storm force extend out about 235 miles (380 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Trami is 17.8.  Th Hurricane Size Index (HSI) is 26.9 and the Hurricane Wind intensity Size Index (HWISI) is 44.7.  Those indices indicate that Typhoon Trami is capable of causing widespread serious damage.

Typhoon Trami is already bringing wind and rain to Okinawa and some of the Ryukyu Islands.  The northern eyewall is over Okinawa and the northern part of the large eye will reach it soon.  Trami will bring strong, damaging winds to Okinawa and the northern Ryukyu Islands during the next 24 hours.  It will also drop heavy rain and flash floods could occur.

Typhoon Trami is moving around the western end of a subtropical ridge.  it will start to move more quickly toward the northeast on Sunday.  Trami could reach Shikoku and Honshu in about 48 hours.  Trmai will still be a typhoon when it reaches the larger islands of Japan.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 30W was passing south of Guam.  At 5:00 p.m. EDT on Friday the center of Tropical Depression 30W was located at latitude 11.6°N and longitude 145.7°E which put it about 110 miles (185 km) south-southeast of Guam.  It was moving toward the northwest at 27 m.p.h. (43 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 1003 mb.  Tropical Depression 30W is forecast to strengthen and it could take track similar to the path of Typhoon Trami.

Tropical Storm Kirk Brings Rain to Lesser Antilles

Tropical Storm Kirk brought rain to some of the Lesser Antilles on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Kirk was located at latitude 13.8°N and longitude 63.6°W which put it about 360 miles (575 km) south-southeast of San Juan, Puerto Rico.  Kirk was moving toward the west-northwest 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 1007 mb.  All Tropical Storm Warnings and Watches have been discontinued.

An upper level trough over the Caribbean Sea is producing strong westerly winds which is blowing over the top of Tropical Storm Kirk.  Those winds are causing strong vertical wind shear, which is causing the strongest thunderstorms to occur on the far eastern side of the circulation.  Bands west of the center of circulation and near the center consist primarily of showers and lower clouds.  The center of circulation is over the eastern Caribbean Sea and the heavy rain is falling hours after the center passed the Lesser Antilles.  Locally heavy rain could cause flash floods in some locations.

Tropical Storm Kirk will move through an environment that will be unfavorable for intensification during the weekend.  Kirk will move over water where the Sea Surface Temperature is near 29°C.  However, the upper level trough will continue cause strong vertical wind shear for the next several days.  Tropical Storm Kirk will likely weaken to a tropical depression or a tropical wave during the next 24 to 48 hours.

Tropical Storm Kirk will move south of a subtropical high pressure system that is over the Atlantic Ocean.  The high will steer Kirk in a general west-northwesterly direction during the weekend.  On its anticipated track Tropical Storm Kirk should stay south of Puerto Rico and the Dominican Republic.  Kirk or its remnants could be near Jamaica in a few days.