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Typhoon Bavi Brings Wind and Rain to Ryukyu Islands

Typhoon Bavi brought wind and rain to the southern Ryukyu Islands on Friday.  At 11:00 p.m. EDT on Friday the center of Typhoon Bavi was located at latitude 25.6°N and longitude 124.1°E which put the center about 165 miles (265 km) east-northeast of Taipei, Taiwan.  Bavi was moving toward the north-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 953 mb.

A weather station in Ishigakijima Island reported at sustained wind speed of 49 m.p.h. (80 km/h).  A weather station in Nakasuji, Japan reported a sustained wind speed of 53 m.p.h. (85 km/h).

Typhoon Bavi strengthened a little as it approached the southern Ryukyu Islands on Friday.  More thunderstorms formed near the center of Bavi’s circulation.  Concentric eyewalls appeared for a time on radar images from the Japan Meteorological Agency.  A small inner eye and eyewall was surrounded by a much larger outer eyewall that was a remnant from the last eyewall replacement cycle.

The distribution of thunderstorms in Typhoon Bavi continued to be asymmetrical.  Thunderstorms were occurring mostly in bands in the southern half of Bavi’s circulation.  Bands in the northern half of Typhoon Bavi consisted primarily of showers and lower clouds.  Storms near the center of Bavi generated more upper level divergence.  The removal of more mass caused the surface pressure to decrease on Friday.

Typhoon Bavi continued to be a very large typhoon.  Winds to typhoon force extended out 175 miles (280 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 370 miles (595 km) from the center of Typhoon Bavi.

The Hurricane Intensity Index (HII) for Typhoon Bavi is 13.9.  The Hurricane Size Index (HSI) is 48.2 and the Hurricane Wind Intensity Size Index (HWISI) is 62.1.  Typhoon Bavi is similar in size and intensity to Hurricane Sandy when Sandy hit the east coast of the U.S. in 2012.

Typhoon Bavi will move through an environment that will be marginally favorable for intensification during the next 12 hours.  Bavi will move over water where the Sea Surface Temperatures are near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Bavi will move through a region of drier air that is near eastern of Chin.a  The drier air will inhibit intensification.  Typhoon Bavi could maintain its intensity during the next 12 hours.

Typhoon Bavi will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Bavi toward the northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Bavi will reach the east coast of China near Wenzhou in 12 hours.

Typhoon Bavi will bring strong winds and heavy rain to Zhejiang.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Bavi could also cause a storm surge of up to 10 feet (3 meters) along parts of the east coast of China.

Typhoon Bavi Approaches Southern Ryukyu Islands

Typhoon Bavi was approaching the southern Ryukyu Islands on Thursday evening.  At 11:00 p.m. EDT on Thursday the center of Typhoon Bavi was located at latitude 21.3°N and longitude 126.9°E which put the center about 360 miles (580 km) southeast of Ishigakijima, Japan.  Bavi was moving toward the northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 964 mb.

Typhoon Bavi weakened on Thursday when it moved into a region of drier air that was east of Taiwan.  The drier air caused many of the thunderstorms in the northern half of Bavi’s circulation to dissipate.  Bands in the northern side of Typhoon Bavi consisted primarily of showers and lower clouds.  Thunderstorms were still occurring in bands in the southern half of Bavi’s circulation.  Storms near the center of Bavi generated less upper level divergence.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure continued to increase on Thursday.

The inner end of a rainband was wrapping back around the southern and eastern sides of the center of Typhoon Bavi on Thursday evening.  A new small eye appeared to be developing at the center of Bavi’s circulation.

Even though Typhoon Bavi weakened on Thursday, it continued to be a very large typhoon.  Winds to typhoon force extended out 185 miles (295 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 370 miles (595 km) from the center of Typhoon Bavi.

The Hurricane Intensity Index (HII) for Typhoon Bavi is 12.7.  The Hurricane Size Index (HSI) is 57.5 and the Hurricane Wind Intensity Size Index (HWISI) is 70.2.  Typhoon Bavi is similar in intensity to Hurricane Sandy when Sandy hit the east coast of the U.S. in 2012.  Typhoon Bavi is larger than Hurricane Sandy was.

Typhoon Bavi will move through an environment that will be somewhat favorable for intensification during the next 24 hours.  Bavi will move over water where the Sea Surface Temperatures are near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Bavi will continue to move through a region of drier air that is east of Taiwan.  The drier air will inhibit intensification, but drier air may have less of an effect on Friday.  Typhoon Bavi could intensify during the next 24 hours, especially if a new eye and eyewall develop at the center of Bavi’s circulation.

Typhoon Bavi will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Bavi toward the northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Bavi will reach the southern Ryukyu Islands in 18 hours.  The center of Bavi will be near northeastern Taiwan in 24 hours.

Typhoon Bavi will bring strong winds and heavy rain to the southern Ryukyu Islands and to Taiwan.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Bavi could cause a storms surge of up to 10 feet (3 meters) along the coast of the southern Ryukyu Islands and northern Taiwan.

Typhoon Bavi Moves Toward Southern Ryukyu Islands

Typhoon Bavi continued to move toward the southern Ryukyu Islands and Taiwan on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Bavi was located at latitude 18.6°N and longitude 129.6°E which put the center about 605 miles (975 km) southeast of Ishigakijima, Japan.  Bavi was moving toward the northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 944 mb.

The cumulative effects of multiple eyewall replacement cycles caused Typhoon Bavi to weaken on Wednesday.  The most recent inner eyewall weakened and a much larger eye with a diameter of 70 miles (110 km) formed at the center of Bavi’s circulation.  The large eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms revolved around the center of Typhoon Bavi.  Storms near the center of Bavi generated less upper level divergence that pumped less mass away from the typhoon.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased again on Wednesday.

The effects of the multiple eyewall replacement cycles also created a very large circulation around typhoon Bavi.  Winds to typhoon force extended out 160 miles (260 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 335 miles (540 km) from the center of Typhoon Bavi.

The Hurricane Intensity Index (HII) for Typhoon Bavi is 23.6. The Hurricane Size Index (HSI) is 54.9 and the Hurricane Wind Intensity Size Index (HWISI) is 78.5.  Typhoon Bavi is similar in intensity to Hurricane Katrina when Katrina hit Mississippi in 2005.  Typhoon Bavi is much larger than Katrina was.

Typhoon Bavi will move through an environment that will be somewhat unfavorable for a powerful typhoon during the next 24 hours.  Bavi will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, Typhoon Bavi will move into a region of drier air that is east of Taiwan.  The drier air will inhibit the formation of new thunderstorms in the northwestern part of Bavi’s circulaiton.  Typhoon Bavi is likely to weaken slowly during the next 24 hours because of the drier air and the lingering effects of the eyewall replacement cycles.

Typhoon Bavi will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Bavi toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Bavi will approach the southern Ryukyu Islands in 36 hours.  The center of Bavi will be near northeastern Taiwan in 48 hours.

Typhoon Bavi will bring strong winds and heavy rain to the southern Ryukyu Islands and to Taiwan.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Bavi could cause a storms surge of up to 12 feet (3.6 meters) along the coast of the southern Ryukyu Islands and northern Taiwan.

Typhoon Bavi Churns West

Typhoon Bavi continued to churn westward toward the southern Ryukyu Islands on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Bavi was located at latitude 16.9°N and longitude 134.7°E which put the center about 975 miles (1575 km) east-southeast of Ishigakijima, Japan.  Bavi was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 927 mb.

Typhoon Bavi completed another eyewall replacement cycle on Tuesday.  An circular eye with a diameter of 45 miles (75 km) was at the center of Bavi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms revolved around the center of Typhoon Bavi.  Storms near the center of Bavi generated upper level divergence that pumped mass away from the typhoon. The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure did not change much on Tuesday.

There was a large circulation around Typhoon Bavi.  Winds to typhoon force extended out 105 miles (165 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 310 miles (500 km) from the center of Typhoon Bavi.

The Hurricane Intensity Index (HII) for Typhoon Bavi is 31.6.  The Hurricane Size Index (HSI) is 37.9 and the Hurricane Wind Intensity Size Index (HWISI) is 69.5. Typhoon Bavi is similar in intensity to Hurricane Laura when Laura hit Southwest Louisiana in 2020.  Typhoon Bavi is much larger than Laura was.

Typhoon Bavi will more through an environment that will be favorable for a powerful typhoon during the next 24 hours.  Bavi will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Bavi could maintain its intensity during the next 24 hours unless another eyewall replacement cycle occurs.

Typhoon Bavi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Bavi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Bavi will approach the southern Ryukyu Islands and Taiwan in less than 72 hours.

Tropical Storm Mekkhala Passes West of Okinawa

The center of Tropical Storm Mekkhala passed west of Okinawa on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Mekkhala was located at latitude 27.9°N and longitude 127.5°E which put the center about 80 miles (130 km) northwest of Okinawa.  Mekkhala was moving toward the north-northeast at 9 m.p.h. (15 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 983 mb.

Tropical Storm Mekkhala continued to weaken as it passed west of Okinawa on Thursday.  Mekkhala moved under the southern part of an upper level trough that was over South Korea,  The upper level trough produced westerly winds that blew toward the top of Mekkhala’s circulation.  Those winds caused strong vertical wind shear.  The strong vertical wind shear blew the tops off of most of the thunderstorms in Tropical Storm Mekkhala.  Bands revolving around the center of Mekkhala’s circulation consisted primarily of showers and lower clouds.

The distribution of wind speeds in Tropical Storm Mekkhala became more asymmetrical on Thursday.  Winds to tropical storm force extended out 140 miles (225 km) in the eastern side of Mekkhala’s circulation.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Tropical Storm Mekkhala.

Tropical Storm Mekkhala will move through an environment that will be unfavorable for intensification during the next 24 hours.  Mekkhala will move over water where the Sea Surface Temperatures are near 26°C.  However, the upper level trough over South Korea will continue to cause strong vertical wind shear.  Tropical Storm Mekkhala could weaken to a tropical depression during the next 24 hours.

Tropical Storm Mekkhala will move around the northwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Mekkhala toward the east-northeast during the next 24 hours.  On its anticipated track, Tropical Storm Mekkhala will be near Tokyo in 36 hours.

Tropical Storm Mekkhala could bring gusty winds to the southern coast of Honshu including Tokyo during the next 48 hours.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Higos strengthened south of Japan.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Higos was located at latitude 26.3°N and longitude 133.9°E which put the center about 155 miles (250 km) east-southeast of Minamidaitojima, Japan.  Higos was moving toward the north at 30 m.p.h. (48 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 986 mb.

Tropical Storm Mekkhala Nears Southern Ryukyu Islands

Tropical Storm Mekkhala was nearing the southern Ryukyu Islands on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Mekkhala was located at latitude 24.1°N and longitude 125.6°E which put the center about 45 miles (75 km) south of Miyakojima, Japan.  Mekkhala was moving toward the north-northeast at 13 m.p.h. (21 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 986 mb.

Former Typhoon Mekkhala weakened to a tropical storm as it approached the southern Ryukyu Islands on Wednesday.  An upper level ridge over China continued to produce northeasterly winds that blew toward the top of Mekkhala’s circulation.  Those winds caused strong vertical wind shear.  The strong vertical wind shear caused former Typhoon Mekkhala to weaken to a tropical storm.

The northeasterly winds in the upper levels also continued to blow the tops off of many of the thunderstorms that tried to form in the northern half of Tropical Storm Mekkhala.  A few more thunderstorms did develop near the center of Mekkhala’s circulation.  Thunderstorms were also occurring in bands in the southern half of Tropical Storm Mekkhala.  Bands in the northern half of Mekkhala still consisted primarily of showers and lower clouds.  Storms near the center of Mekkhala generated upper level divergence that pumped mass away to the south and west of the typhoon.  However, the removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure continued to increase on Wednesday.

The size of the circulation around Tropical Storm Mekkhala increased a little on Wednesday.  Winds to tropical storm force extended out 165 miles (265 km) from the center of Mekkhala’s circulation.

Tropical Storm Mekkhala will move through an environment that will be unfavorable for intensification during the next 24 hours.  Mekkhala will move over water where the Sea Surface Temperatures are near 27°C.  However, the upper level ridge over China will continue to cause vertical wind shear.  The vertical wind shear may be a little less on Thursday.  Tropical Storm Mekkhala could maintain its intensity during the next 24 hours if the vertical wind shear is a little less.

Tropical Storm Mekkhala will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Mekkhala toward the northeast during the next 24 hours.  On its anticipated track, Tropical Storm Mekkhala will pass over Miyakojima during the next few hours.  Mekkhala could be near Okinawa in 12 hours.

Tropical Storm Mekkhala will bring strong winds and locally heavy rain to the southern Ryukyu Islands including Ishigakijima and Miyakojima.  Heavy rain could cause flash floods in some locations.  Mekkhala will also bring gusty winds and locally heavy rain to Okinawa.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression Higos strengthened back to a tropical storm on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Higos was located at latitude 18.3°N and longitude 137.1°E which put the center about 540 miles (870 km) south-southwest of Iwo To.  Higos was moving toward the northwest at 14 m.p.h. (22 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 1002 mb.

Typhoon Mekkhala Weakens

Typhoon Mekkhala weakened on Tuesday as it moved toward the southern Ryukyu Islands.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Mekkhala was located at latitude 21.3°N and longitude 124.7°E which put the center about 235 miles (380 km) south of Miyakojima, Japan.  Mekkhala was moving toward the north at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 974 mb.

Typhoon Mekkhala weakened on Tuesday.  An upper level ridge over China produced northeasterly winds that blew toward the top of Mekkhala’s circulation.  Those winds caused strong vertical wind shear.  The strong vertical wind shear caused Typhoon Mekkhala to weaken.

The northeasterly winds in the upper levels also blew the tops off of many of the thunderstorms in the northern half of Typhoon Mekkhala.  Thunderstorms were still occurring in bands in the southern half of Mekkhala’s circulation.  Bands in the northern half of Typhoon Mekkhala consisted primarily of showers and lower clouds.  Storms near the center of Mekkhala generated upper level divergence that pumped mass away to the south and west of the typhoon.  However, the removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Tuesday.

Even though Typhoon Mekkhala weakened on Tuesday, the size of Mekkhala’s circulation did not change much.  Winds to typhoon force extended out 65 miles (105 km) from the center of Typhoon Mekkhala.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Mekkhala’s circulation.

Typhoon Mekkhala will move through an environment that will be unfavorable for intensification during the next 24 hours.  Mekkhala will move over water where the Sea Surface Temperatures are near 28°C.  However, the upper level ridge over China will continue to cause strong vertical wind shear.  Typhoon Mekkhala will continue to weaken during the next 24 hours because of the strong vertical wind shear.

Typhoon Mekkhala will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Mekkhala toward the north during the next 24 hours.  On its anticipated track, Typhoon Mekkhala will reach the southern Ryukyu Islands in less than 24 hours.

Typhoon Mekkhala will bring strong winds and locally heavy rain to the southern Ryukyu Islands including Ishigakijima and Miyakojima.  Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Higos weakened to a tropical depression as it moved west of the Marianas.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Higos was located at latitude 15.4°N and longitude 141.3°E which put the center about 225 miles (360 km) west-northwest of Guam.  Higos was moving toward the west-northwest at 11 m.p.h. (17 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 1002 mb.

Tropical Storm Higos Forms Near the Marianas

Tropical Storm Higos formed over the Western North Pacific Ocean near the Marianas on Monday evening.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Higos was located at latitude 14.8°N and longitude 145.1°E which put the center about 20 miles (30 km) south of Tinian.  Higos was moving toward the west-northwest at 11 m.p.h. (17 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.

Tropical Storm Warnings are in effect for Tinian and Saipan.

A low pressure system near the Marianas strengthened on Monday evening and the Japan Meteorological Agency designated the system as Tropical Storm Higos.

A weather station at the Saipan International Airport (PGSN) reported a sustained wind speed of 38 m.p.h. (61 km/h) and a wind gust of 60 m.p.h. (96 km/h).

The distribution of thunderstorms in Tropical Storm Higos was asymmetrical.  Thunderstorms were occurring in bands in the northern and western parts of Higos’ circulation.  Bands in the southern and eastern parts of Tropical Storm Higos consisted primarily of showers and lower clouds.  Storms near the center of HIgos began to generate upper level divergence that pumped mass away to the west of the tropical storm.

The distribution of wind speeds in Tropical Storm Higos was also asymmetrical.  Winds to tropical storm force extended out 80 miles (130 km) in the northern half of Higos’ circulation.  The winds in the southern half of Tropical Storm Higos were blowing at less than tropical storm force.

Tropical Storm Higos will move through an environment that will be somewhat favorable for intensification.  Higos will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is south of Japan. The upper level ridge will produce easterly winds that will blow toward the top of Higos’ circulation.  Those winds will cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification.  Tropical Storm Higos could intensify during the next 24 hours.

Tropical Storm Higos will move around the western end of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer HIgos toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Higos will move gradually away from the Marianas.

Tropical Storm Higos will bring gusty winds and locally heavy rain to Tinian and Saipan.  Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Typhoon Mekkhala started to move toward the southern Ryukyu Islands.  At 11:00 p.m. EDT on Monday the center of Typhoon Mekkhala was located at latitude 19.2°N and longitude 125.1°E which put the center about 370 miles (595 km) south of Miyakojima, Japan.  Mekkhala was moving toward the west-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 943 mb.

Typhoon Mekkhala Strengthens to Equivalent of Cat. 4 Hurricane

Typhoon Mekkhala strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Monday as it moved over the Western North Pacific Ocean east of northern Luzon.  At 11:00 a.m. EDT on Monday the center of Typhoon Mekkhala was located at latitude 18.3°N and longitude 125.9°E which put the center about 305 miles (490 km) east of Aparri, Philippines.  Mekkhala was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 937 mb.

Typhoon Mekkhala strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Monday.  A circular eye with a diameter of 25 miles (40 km) was present at the center of Typhoon Mekkhala.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Mekkhala’s circulation.  Storms near the center of Mekkhala generated strong upper level divergence that pumped mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease.

The distribution of winds speeds in Typhoon Mekkhala was fairly symmetrical.  Winds to typhoon force extended out 25 miles (40 km) from the center of Mekkhala’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Mekkhala.

The Hurricane Intensity Index (HII) for Typhoon Mekkhala is 29.9. The Hurricane Size Index (HSI) is 10.0 and the Hurricane Wind Intensity Size Index (HWISI) is 39.9.  Typhoon Mekkhala is similar in intensity to Hurricane Charley when Charley hit Southwest Florida in 2004.  Mekkhala is a little larger than Charley was.

Typhoon Mekkhala will move through an environment favorable for intensification during the next 24 hours.  Mekkhala will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge that is southwest of Japan. The upper level winds are weak in the middle of the ridge and there will be little vertical wind shear.  Typhoon Mekhala could intensify during the next 24 hours unless the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form, then an eyewall replacement cycle would cause Mekkhala to weaken.  Typhoon Mekkhala could strengthen to the equivalent of a Category 5 hurricane, if there is no eyewall replacement cycle.

Typhoon Mekkhala will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Mekkhala toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Mekkhala will move toward the southern Ryukyu Islands.  Mekkhala could approach the southern Ryukyu Islands in 60 hours.

Tropical Depression Forms West of Guam

Tropical Depression 07W formed over the Western North Pacific Ocean west-southwest of Guam on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Depression 07W was located at latitude 13.1°N and longitude 142.5°E which put the center about 150 miles (240 km) west-southwest of Guam.  Tropical Depression 07W was moving toward the west-northwest at 17 m.p.h. (28 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 1005 mb.

A low pressure system over the Western North Pacific Ocean west-southwest of Guam strengthened on Thursday night and both the Japan Meteorological Agency and the U.S. Joint Typhoon Warning Center classified the system as a tropical depression.

The distribution of thunderstorms in Tropical Depression 07W was asymmetrical.  Thunderstorms were occurring in bands in the southern half of the tropical depression.  Bands in the northern half of Tropical Depression 07W consisted primarily of showers and lower clouds.  Storms near the center of circulation began to generate upper level divergence that pumped mass away to the west of the tropical depression.  The removal of mass caused the surface pressure to decrease.

Tropical Depression 07W will move through an environment mostly favorable for intensification during the next 24 hours.  The tropical depression will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southern part of an upper level ridge that is southwest of Japan.  The upper level ridge will produce northeasterly winds that will blow toward the top of the tropical depression.  Those winds will cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Tropical Depression 07W is likely to intensify to a tropical storm during the next 24 hours.  It could strengthen to a typhoon during the weekend.

Tropical Depression 07W will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer the tropical depression toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Depression 07W will move away from the Marianas.