Tag Archives: HWISI

Powerful Hurricane Michael Nearing North Florida

Powerful hurricane Michael was nearing north Florida on Wednesday morning.  Michael intensified rapidly to Category 4 on the Saffir-Simpson Scale during the overnight hours.  At 8:00 a.m. EDT on Wednesday the center of Hurricane Michael was located at latitude 29.0°N and longitude 86.3°W which put it about 90 miles south-southwest of Panama City, Florida.  Michael was moving toward the north at 13 m.p.h. (20 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 933 mb.

A Hurricane Warning was in effect for the portion of the coast from the Alabama-Florida border to Suwanee River, Florida.  Tropical Storm Warnings were in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border and from Suwanee River to Chassahowitzka, Florida.  A Tropical Storm Warning was in effect for the Atlantic Coast from Fernandina Beach, Florida to Surf City, North Carolina.  Tropical Storm Watches were in effect for the portions of the coast from the Alabama-Mississippi border to the Mouth of the Pearl River and from Chassahowitzka to Anna Maria Island, Florida.  A Tropical Storm Watch was also in effect from Surf City to Duck, North Carolina including Albemarle and Pamlico Sounds.

Hurricane Michael intensified rapidly during the past 12 hours.  An eye with a diameter of 20 miles (32 km) is surrounded by a ring of strong thunderstorms.  The strongest winds are occurring in that ring of storms.  Storms near the core of Hurricane Michael are generating strong upper level divergence which is pumping large quantities of mass away from the hurricane.  The removal of mass allowed the surface pressure to decrease rapidly to 933 mb.

Winds to hurricane force extend out about 45 m.p.h. (75 km/h) from the center of Hurricane Michael.  Winds to tropical storm force extend out about 185 miles (290 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Michael is 29.9.  The Hurricane Size Index (HSI) is 16.1 and the Hurricane Wind Intensity Size Index (HWISI) is 46.0.  Hurricane Michael is capable of causing regional significant damage.

Hurricane Michael is stronger than any other hurricane to hit north Florida in the historical record.  Michael is similar in intensity to what Hurricane Charley was when Charley hit southwest Florida in 2004.  Hurricane Michael is bigger than Charley was in 2004.

An upper level trough over the Central U.S. and a subtropical high pressure system over the western Atlantic Ocean are combining to steer Hurricane Michael toward the north.  The trough will turn Michael toward the northeast when it reaches the coast.  On its anticipated track Hurricane Michael will make landfall near Panama City and Port St. Joe, Florida in about six hours.

Hurricane Michael will bring destructive winds to the coast of north Florida.  The strongest winds will be near the center and east of the center.  Those winds will push water toward the coast and a storm surge of 10 to 15 feet (3 to 5 meters) will occur east of where the center of Michael makes landfall.  The coast of the northeast Gulf of Mexico is very vulnerable to storm surges and significant damage will occur.

The center of Hurricane Michael will move between Dothan, Alabama and Tallahassee, Florida.  It will pass near Albany, Georgia and then move south of Macon, Georgia.  The center of Michael could move near Columbia, South Carolina and then it could exit the East Coast of the U.S. near Norfolk, Virginia.

Michael will bring hurricane force winds to northeast Florida, extreme southeast Alabama and southern Georgia.  There will be widespread power outages.  Winds to tropical storm force will occur in South Carolina and North Carolina.  Hurricane Michael will drop locally heavy rain when it moves inland.  The wind and rain will disrupt efforts to recover from the effects of Hurricane Florence in South Carolina and North Carolina.

Michael Strengthens to a Major Hurricane

Hurricane Michael strengthened into a major hurricane on Tuesday afternoon.  At 5:00 p.m. EDT on Tuesday the center of Hurricane Michael was located at latitude 26.0°N and longitude 86.4°W which put it about 290 miles (470 km) south of Panama City, Florida.  Michael was moving toward the north at 12 m.p.h. (19 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 957 mb.

A Hurricane Warning is in effect for the portion of the coast from the Alabama-Florida border to the Suwanee River, Florida.  Tropical Storm Warnings are in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border, from Suwanee River to Chassahowitzka, Florida and from Fernandina Beach, Florida to South Santee River, South Carolina on the Atlantic Coast.  Tropical Storm Watches are in effect for the portions of the coast from the Alabama-Mississippi border to the Mouth of the Pearl River, from Chassahowitzka to Anna Maria Island, Florida and from South Santee, River South Carolina to Duck, North Carolina including Albemarle and Pamlico Sounds.

The inner core of Hurricane Michael tightened on Tuesday afternoon.  The diameter of the eye decreased from 30 miles (50 km) to 22 miles (35 km).  The ring of thunderstorms around the eye tightened around the smaller eye and the strongest winds were closer to the center of circulation.  Storms around the core of Michael were generating upper level divergence which was pumping mass away from the hurricane.  The removal of mass allowed the surface pressure to decrease from 965 mb to 957 mb during the past six hours.

Winds to hurricane force extend out about 45 miles (75 km) from the center of Hurricane Michael.  Winds to tropical storm force extend out about 170 miles (280 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Michael is 22.1.  The Hurricane Size Index (HSI) is 14.6 and the Hurricane Wind Intensity Size Index (HWISI) is 36.7.  Hurricane Michael is capable of causing regional major damage.

Hurricane Michael will move through an environment favorable for intensification for another 12 to 18 hours.  Michael will move over water where the Sea Surface Temperature is near 29°C.  An upper level trough over the Central U.S. is producing westerly winds which are blowing toward the top of Hurricane Michael, but those winds are not causing enough vertical wind shear to prevent intensification.  Hurricane Michael could intensify to Category 4 on the Saffir-Simpson Scale before it makes landfall.

Hurricane Michael is moving between a subtropical high pressure system over the western Atlantic Ocean and the upper level trough over the Central U.S.  Those two weather systems are steering Michael toward the north and that general motion is expected to continue for another 12 hours.  On its anticipated track Hurricane Michael will make landfall near Panama City and Port St. Joe, Florida early on Wednesday afternoon.  The upper level trough will steer Michael more toward the northeast after it makes landfall.  The center of Michael is likely to move between Dothan, Alabama and Tallahassee, Florida and it could pass near Albany, Georgia.

Hurricane Michael will bring strong winds to northwest Florida, extreme southeast Alabama and southern Georgia.  There will be wind damage and widespread power outages could occur.  The coast of the northeastern Gulf of Mexico is very vulnerable to storm surges.  Hurricane Michael will produce a storm surge of 10 to 15 feet (3 to 5 meters) at some points along the coast.  Michael will drop locally heavy rain.  Although Hurricane Michael will weaken when it moves inland, it will bring gusty winds and heavy rain to South Carolina and North Carolina.  Hurricane Michael will hinder efforts in those states to recover from the effects of Hurricane Florence.

Michael Strengthens Into a Hurricane, Watches Issued for Gulf Coast

Former Tropical Storm Michael strengthened into a hurricane on Monday morning and Watches were issued for portions of the Gulf Coast.  At 11:00 a.m. EDT on Monday the center of Hurricane Michael was located at latitude 21.2°N and longitude 84.9°W which put it about 50 miles (80 km) south of the western end of Cuba.  Michael was moving toward the north at 7 m.p.h. (11 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 982 mb.

A Hurricane Watch was in effect for the portion of the coast from the Alabama-Florida border to Suwanee River, Florida.  Tropical Storm Watches were in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border and from Suwanee River to Anna Maria Island, Florida.  A Hurricane Warning was in effect for the Cuban province of Pinar del Rio.  Tropical Storm Warnings were in effect for the Cuban province of Isle of Youth and for the portion of the coast from Tulum to Cabo Catoche, Mexico.

Hurricane Michael continued to organize quickly.  A circular eye with a diameter of about 30 miles (50 km) was forming at the center of Michael.  A ring of strong thunderstorms was wrapping around the eye and the strongest winds were occurring in the ring of storms.  Several bands of showers and thunderstorms were wrapping around the core of Hurricane Michael.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.

Winds to hurricane force extended out about 30 miles (50 km) primarily to the northeast of the center of Hurricane Michael.  Winds to tropical storm force extended out about 175 miles (280 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Michael was 10.4.  The Hurricane Size Index (HSI) was 6.8 and the Hurricane Wind Intensity Size Index (HWISI) was 17.2.

Hurricane Michael will move into an environment that will become increasingly favorable for intensification.  Michael will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation.  Those winds were causing some vertical wind shear.  However, the upper level trough will move westward away from Hurricane Michael and the wind shear will decrease.  Hurricane Michael will continue to strengthen when it moves over the Gulf of Mexico and it could intensify rapidly once the eye and eyewall are fully formed.  Hurricane Michael is likely to strengthen into a major hurricane.

Hurricane Michael will move around the western end of a subtropical high pressure system centered over the western Atlantic Ocean.  The high will steer Michael in a northerly direction during the next several days.  It will get bigger and stronger during the next 48 hours.  On its anticipated track Hurricane Michael will approach the northeast coast of the Gulf of Mexico on Wednesday.  It is likely to be a major hurricane at that time.  Hurricane Michael has the potential to cause a storm surge of 10 to 15 feet (3 to 5 meters) at the coast.  It will bring strong winds which could cause regional major damage and result in significant power outages.  Locally heavy rain could cause flooding in some locations.

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.

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.

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.

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.

Hurricane Rosa Rapidly Intensifies Into a Major Hurricane Southwest of Baja California

Hurricane Rosa rapidly intensified into a major hurricane southwest of Baja California on Thursday.  At 5:00 p.m. EDT on Thursday the center of Hurricane Rosa was located at latitude 16.9°N and longitude 115.9°W which put it about 570 miles (915 km) southwest of the southern tip of Baja California.  Rosa was moving toward the west at 10 m.p.h. (16 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. (240 km/h).  The minimum surface pressure was 953 mb.

Hurricane Rosa rapidly intensified into a powerful hurricane on Thursday and a circular eye developed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in the ring of storms.  The circulation around Hurricane Rosa was symmetrical.  Several bands of showers and thunderstorms were revolving around the core of the hurricane.  Storms around the core were generating strong upper level divergence which was pumping mass away from the hurricane.

The circulation around Hurricane Rosa was relatively small.  Winds to hurricane force only extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out about 115 miles (185 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Rosa was 23.6.  The Hurricane Size Index (HSI) was 9.8 and the Hurricane Wind Intensity Size Index (HWISI) was 33.4.

Hurricane Rosa will continue to move through an environment favorable for intensification during the next 12 to 24 hours.  Rosa 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 during the shorter term.  If a rainband wraps around the existing eye and eyewall, an eyewall replacement cycle could halt the current period of rapid intensification.  Hurricane Rosa will start to move over cooler water during the weekend.  An upper level low west of California will produce southwesterly winds which will blow toward the top of Rosa’s circulation.  Those winds will cause more vertical wind shear and they could cause Rosa to weaken more quickly.

Hurricane Rosa will move around the western end of a ridge of high pressure over northern Mexico on Friday.  Rosa will start to move more toward the north when it moves around the western end of the ridge.  The upper level trough east of California will turn Rosa more toward the northeast during the weekend.  On its anticipated track Rosa could approach Baja California early next week.  It may weaken to a tropical storm before it gets to Baja California, but it still will have the potential to drop heavy rain.

Typhoon Trami Moves Slowly Toward Okinawa

Typhoon Trami moved slowly toward Okinawa on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Trami was located at latitude 21.5°N and longitude 129.1°E which put it about 345 miles (560 km) south of Okinawa.  Trami was moving toward the north at 3 m.p.h. (5 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 949 mb.

The structure of Typhoon Trami changed significantly during the past 48 hours.  A second eyewall replacement cycle produced a larger eye and a bigger circulation.  Very slow movement of Typhoon Trami allowed the wind to mix cooler water to the surface.  Cooler water meant that there was less energy in the upper ocean to fuel the circulation.  The combination of the eyewall replacement cycle and cooler water resulted in a reduction of the wind speed and the surface pressure increased.

Although it is not as strong as it was 48 hours ago , Typhoon Trami is still a large powerful typhoon.  Winds to typhoon force extend out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extend out about 225 miles (360 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Trami is 17.8.  The Hurricane Size Index (HSI) is 24.5 and the Hurricane Wind Intensity Size Index (HWISI) is 42.3.  Typhoon Trami is capable of producing widespread serious damage.

Typhoon Trami is likely to weaken slowly while it remains over the cooler water it has mixed to the surface.  When Trami moves north of that water in 12 to 24 hours, it will move into a more favorable environment.  Typhoon Trami will move over water where the Sea Surface Temperature is near 29°C.  It will still be in an area where the upper level winds are not too strong and there will not be much vertical wind shear.  The broad circulation and large eye will prevent rapid intensification, but Typhoon Trami could strengthen on Friday.

Typhoon Trami will still be in area where the steering winds are weak on Thursday.  It will move slowly toward the north during the next 12 to 24 hours.  Eventually a subtropical ridge over the Western North Pacific Ocean will begin to steer Typhoon Trami again.  Typhoon Trami will move toward the north at a faster rate on Friday.  On its anticipated track Typhoon Trami could be near Okinawa by late Friday.  Typhoon Trami could approach Kyushu in about 72 hours and it could move across Honshu during the weekend.