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.

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.

Tropical Storm Kirk Redevelops East of Lesser Antilles, Warnings Issued

Tropical Storm Kirk redeveloped east of the Lesser Antilles on Wednesday morning and Tropical Storm Warnings and Watches were issued for some of those islands.  At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Kirk was located at latitude 12.1°N and longitude 54.3°W which put it about 360 miles (575 km) east-southeast of Barbados.  Kirk 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.

Tropical Storm Warnings have been issued for Barbados, St. Lucia, Dominica, Martinique and Guadeloupe.  A Tropical Storm Watch has been issued for St. Vincent and the Grenadines.

The National Hurricane Center (NHC) indicated that former Tropical Storm Kirk had weakened to a tropical wave on Monday and NHC ceased issuing advisories on the system.  The remnants of former Tropical Storm Kirk moved quickly westward across the tropical Atlantic Ocean.  More thunderstorms began developing in the system on Tuesday.  NHC determined that sufficient thunderstorms had formed near the center of circulation by Wednesday morning to reclassify the system as a tropical cyclone and it started issuing advisories on Tropical Storm Kirk again.

A cluster of strong thunderstorms developed near the center of Tropical Storm Kirk.  Thunderstorms were also forming in several bands which were revolving around the center of circulation.  Thunderstorms near the core of Kirk were generating upper level divergence which was pumping mass away to the east of the tropical storm.

Tropical Storm Kirk will move through an environment favorable for intensification during the next 24 hours.  Kirk 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 not too strong.  There will be some vertical wind shear, but the wind shear will not be strong enough to prevent intensification in the short term.  When Tropical Storm Kirk moves over the eastern Caribbean Sea, it will encounter stronger westerly winds and the vertical wind shear will increase.

Tropical Storm Kirk will move south of the subtropical high pressure system over the Atlantic Ocean.  The subtropical high will steer Kirk on a path a little north of due west.  On its anticipated track Tropical Storm Kirk could be near Barbados on Thursday morning.  Kirk could reach the Lesser Antilles later on Thursday.  Tropical Storm Kirk will bring gusty winds and it could drop locally heavy rain.