Monthly Archives: September 2024

Tropical Storm Bebinca Forms Near Guam

Tropical Storm Bebinca formed near Guam on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Bebinca located at latitude 13.6°N and longitude 144.0°E which put the center about 20 miles (30 km) southwest of Guam.  Bebinca was moving toward the west-northwest at 13 m.p.h. (20 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 999 mb.

Tropical Storm Warnings were in effect for the coastal waters of Guam, Rota, Tinian and Saipan.

A low pressure system near Guam strengthened on Tuesday and the Japan Meteorological Agency designated the system as Tropical Storm Bebinca.  Bebinca brought wind and rain to the Marianas.  A weather station at Guam International Airport (PGUM) reported a sustained wind speed of 28 m.p.h. (45 km/h) and a wind gust of 45 m.p.h. (73 km/h).

The circulation around Tropical Storm Bebinca was exhibiting more organization on Tuesday afternoon.  More thunderstorms developed near the center of Bebinca’s circulation.  Thunderstorms also formed in bands in the eastern side of Tropical Storm Bebinca.  Bands in the western side of Bebinca’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Bebinca generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the pressure to decrease.

The distribution of winds speeds in Tropical Storm Bebinca was asymmetrical.  Winds to tropical storm force extended out 100 miles (160 km) in the northeastern quadrant of Bebinca’s circulation.  Winds to tropical storm force only extended out 25 miles (40 km) in the other parts of Tropical Storm Bebinca.

Tropical Storm Bebinca will move through an environment favorable for intensification during the next 24 hours.  Bebinca will move over water where the Sea Surface Temperatures are near 30°C.   It will move under the western part of an upper level ridge over the Western North Pacific Ocean.  The upper level ridge will produce southerly winds that will blow toward the top of Bebinca’s circulation.  Those winds will cause some vertical wind shear.  The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification.  Tropical Storm Bebinca will intensify during the next 24 hours.  Bebinca is likely to strengthen to a typhoon later this week.

Tropical Storm Bebinca will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Bebinca toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Bebinca will move west of the Marianas.  Bebinca could approach the Ryukyu Islands by the end of the week.

Tropical Storm Francine Churns over Western Gulf of Mexico

Tropical Storm Francine was churning over the western Gulf of Mexico on Tuesday morning.  At 8:00 a.m. EDT on Tuesday the center of Tropical Storm Francine located at latitude 24.5°N and longitude 94.9°W which put the center about 395 miles (640 km) south-southwest of Cameron, Louisiana.  Francine was moving toward the north at 5 m.p.h. (8 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 990 mb.

A Hurricane Warning is in effect for the portion of the coast from Sabine Pass to Grand Isle. Louisiana.

A Tropical Storm Warning is in effect for the portion of the coast from Grand Isle, Louisiana to the Mouth of the Pearl River.  The Tropical Storm Warning includes New Orleans.  The Tropical Storm Warning also includes Lake Pontchartrain and Lake Maurepas.  A Tropical Storm Warning is in effect for the portion of the coast from High Island, Texas to Sabine Pass, Louisiana.  A Tropical Storm Warning is in effect for the portion of the coast from Port Mansfield, Texas to the Mouth of the Rio Grande River.  A Tropical Storm Warning is in effect for the portion of the coast from La Pesca, Mexico to the Mouth of the Rio Grande River.

A Tropical Storm Watch is in effect for the portion of the coast from High Island to Port Mansfield, Texas.  A Tropical Storm Watch is in effect for the portion of the coast from Barra del Tordo to La Pesca, Mexico.

Rainbands in the western side of Tropical Storm Francine were dropping heavy rain on parts of south Texas.  A Flash Flood Warning is in effect for the area around Brownsville, Texas.

The circulation around Tropical Storm Francine showed signs of developing an inner core on Tuesday morning.  The inner end of a rainband wrapped most of the way around the center of Francines’s circulation.  An eye with a diameter of 25 miles (40 km) appeared to be forming at the center of Tropical Storm Francine.  The eye was surrounded by a nearly complete ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were occurring in bands in the northeastern part of Francine’s circulation.  Thunderstorms were also occurring in bands in the western side of Tropical Storm Francine.

The size of the circulation around Tropical Storm Francine contracted a little as it began to resemble a typical tropical cyclone.  Winds to tropical storm force extended out 140 miles (220 km) from the center of Francine’s circulation.

Tropical Storm Francine will move through an environment very favorable for intensification during the next 24 hours.  Francine will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the western Gulf of Mexico.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Tropical Storm Francine will intensify to a hurricane during the next 24 hours.  Francine could intensify rapidly after the inner core is fully formed.

Tropical Storm Francine will move around the western part of a high pressure system that extends from the western Atlantic Ocean to the Gulf of Mexico.  The high pressure system will steer Francine toward the northeast during the next 24 hours.  On its anticipated track, Tropical Storm Francine will move toward Louisiana.  Francine will move faster toward the northeast on Wednesday when an upper level trough over the south central U.S. also begins to steer it toward the coast.  Tropical Storm Francine will approach the coast of Louisiana on Wednesday afternoon.  Francine will be a hurricane when it approaches the coast of Louisiana.

Tropical Storm Francine will bring strong winds and heavy rain to Louisiana.  Francine will be capable of causing serious damage.  Widespread outages of electricity are likely.  Heavy rain is likely to cause flash floods.

Flood Watches are in effect for parts of Louisiana.

Tropical Storm Francine could cause a storm surge of up to 10 feet (3 meters) along parts of the coast of Louisiana.

A Storm Surge Warning is in effect for the portion of the coast from High Island, Texas to the Mouth of the Mississippi River.  The Storm Surge Warning includes Vermilion Bay.

 

 

Tropical Storm Francine Prompts Hurricane Watch for Louisiana

The risk posed by Tropical Storm Francine prompted the issuance of a Hurricane Watch for a portion of the coast of Louisiana on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Francine located at latitude 23.0°N and longitude 94.9°W which put the center about 480 miles (770 km) south-southwest of Cameron, Louisiana.  Francine was moving toward the north-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1002 mb.

A Hurricane Watch is in effect for the portion of the coast from Cameron to Grand Isle, Louisiana.

A Tropical Storm Watch is in effect for the portion of the coast from Grand Isle, Louisiana to the Mississippi/Alabama border.  The Tropical Storm Watch includes New Orleans.  The Tropical Storm Watch also includes Lake Pontchartrain and Lake Maurepas.  A Tropical Storm Watch is in effect for the portion of the coast from High Island, Texas to Cameron, Louisiana.  A Tropical Storm Watch is in effect for the portion of the coast from Port Mansfield, Texas to the Mouth of the Rio Grande River.  A Tropical Storm Watch is in effect for the portion of the coast from Barra del Tordo, Mexico to the Mouth of the Rio Grande River.

A U.S. Air Force Reserve Hurricane Hunter plane investigated a low pressure system over the western Gulf of Mexico previously designated as Potential Tropical Cyclone Six on Monday morning.  The crew of the aircraft found that the circulation around the low pressure system was more organized.  Based on the data from the aircraft, the U.S. National Hurricane Center determined that former Potential Tropical Cyclone Six had developed the characteristics of a tropical storm.  The National Hurricane Center designated former Potential Tropical Cyclone Six as Tropical Storm Francine.

A distinct low level center of circulation formed at the center of Tropical Storm Francine.  Thunderstorms had formed near the center of Francine’s circulation.  More thunderstorms also developed in bands revolving around the center of Tropical Storm Francine.  Storms near the center of Francine generated upper level divergence that pumped mass away from the tropical storm.

The circulation around Tropical Storm Francine was more symmetrical on Monday morning.  Winds to tropical storm force extended out 160 miles (260 km) from the center of Francine’s circulation.

Tropical Storm Francine will move through an environment very favorable for intensification during the next 24 hours.  Francine will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the western Gulf of Mexico.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Tropical Storm Francine is likely to intensify gradually during the next few hours while an inner core develops.  Francine could intensify rapidly on Tuesday after an inner core forms.  Tropical Storm Francine is likely to strengthen to a hurricane on Tuesday.

Tropical Storm Francine will move around the western part of a high pressure system that extends from the western Atlantic Ocean to the Gulf of Mexico.  The high pressure system will steer Francine toward the north during the next 24 hours.  On its anticipated track, Tropical Storm Francine will move toward Louisiana.  Francine will move more toward the northeast on Wednesday when an upper level trough over the south central U.S. begins to steer it toward the coast.  Tropical Storm Francine will approach the coast of Louisiana on Wednesday afternoon.  Francine is likely to be a hurricane when it approaches the coast of Louisiana.

Tropical Storm Francine will bring strong winds and heavy rain to Louisiana.  Francine will be capable of causing serious damage.  Heavy rain is likely to cause flash floods.

Flood Watches are in effect for parts of Louisiana.

Tropical Storm Francine could cause a storm surge of up to 10 feet (3 meters) along parts of the coast of Louisiana.

A Storm Surge Watch is in effect for the portion of the coast from High Island, Texas to the Mouth of the Pearl River.  The Storm Surge Watch includes, Vermillion Bay, Lake Pontchartrain and Lake Maurepas.

 

Low Pressure System over Gulf of Mexico Designated Potential Tropical Cyclone Six

A low pressure system over the southwestern Gulf of Mexico was designated as Potential Tropical Cyclone Six by the U.S. National Hurricane Center on Sunday afternoon.  A Tropical Storm Watch was issued for the coast of northern Mexico.  At 5:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Six located at latitude 21.6°N and longitude 94.6°W which put the center about 340 miles (545 km) south-southeast of the Mouth of the Rio Grande River.  The low pressure system was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1003 mb.

A Tropical Storm Watch was in effect for the portion of the coast from Barra del Tordo,, Mexico to the Mouth of the Rio Grande River.

A U.S. Air Force Reserve Hurricane Hunter reconnaissance aircraft investigated a low pressure system over the southwest Gulf of Mexico that was previously designated as Invest 91L on Sunday afternoon.  The Hurricane Hunters found that there was a large low pressure system with a broad counterclockwise rotation.  The reconnaissance flight was unable to find a distinct low level center of circulation.  The flight crew did find a large area of tropical storm force winds in the western side of the low pressure system.

Winds to tropical storm force extended out 185 miles (295 km) in the western side of Potential Tropical Cyclone Six.  The winds in the eastern side of the low pressure system were blowing at less than tropical storm force.

The strongest winds in Potential Tropical Cyclone Six were occurring in bands of thunderstorms in the southwestern part of the low pressure system.  The bands in the other parts of the circulation consisted primarily of showers and lower clouds.  The storms in the southwestern part of Potential Tropical Cyclone Six began to generate upper level divergence that pumped mass away from the low pressure system.

Potential Tropical Cyclone Six will move through an environment mostly favorable for the intensification during the next 24 hours.  The low pressure system will move over water where the Sea Surface Temperatures are near 30°C.  It will move over the eastern part of an upper level ridge over northern Mexico and the western Gulf of Mexico.  The upper level ridge will produce northwesterly winds that will blow toward the top of Potential Tropical Cyclone Six’s circulation.  Those winds will cause some vertical wind shear.  The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification.  The large size of the circulation around the low pressure system will also reduce the rate of intensification.  Potential Tropical Cyclone Six is likely to intensify slowly during the next 24 hours.  The low pressure system could intensify more rapidly after an inner core forms.

Potential Tropical Cyclone Six will move around the southwestern part of a high pressure system that extends from the western Atlantic Ocean to the Gulf of Mexico.  The high pressure system will steer the low pressure system toward the northwest during the next 24 hours.  On its anticipated track, Potential Tropical Cyclone Six will move toward northern Mexico.  The low pressure system will move more toward the north on Tuesday when it moves around the western end of the high pressure system.  It is likely to be southeast of Texas on Tuesday night.  Potential Tropical Cyclone Six could approach the coast of Louisiana on Wednesday.  It could be a hurricane when it approaches the coast of Louisiana.

Low Pressure System Forms over Bay of Campeche

A low pressure system formed over the Bay of Campeche on Saturday.  The low pressure system was designated as Invest 91L.  At 8:00 a.m. EDT on Saturday the center of the low pressure system was located at latitude 18.8°N and longitude 92.7°W which put the center about 150 miles (240 km) west of Campeche, Mexico.  The low pressure system was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1005 mb.

A low pressure system formed in the northern end of a tropical wave over the eastern Bay of Campeche on Saturday.  There was a well developed low level center of circulation that was visible on satellite images.  However, there were few thunderstorms near the center of circulation.  Thunderstorms were starting to form in bands in the eastern side of the low pressure system.  Bands in the rest of the low pressure system consisted primarily of showers and lower clouds.

The low pressure system designated as Invest 91L will move into an environment mostly favorable for the formation of a tropical cyclone during the next 36 hours.  The low pressure system will move over water where the Sea Surface Temperatures are near 31°C.  It will move over the eastern part of an upper level ridge over northern Mexico and the western Gulf of Mexico.  The upper level ridge will produce northerly winds that will blow toward the top of Invest 91L’s circulation.  Those winds will cause moderate vertical wind shear.  The wind shear will inhibit the formation of a tropical cyclone, but the shear will not be enough to prevent the formation of a tropical depression or a tropical storm.

There is a second low pressure system embedded in a nearly stationary front over the northwestern Gulf of Mexico.  The second low pressure system could drift toward the southwest during the next day or two.  It is possible that the circulation around the second low pressure system and the circulation around Invest 91L could merge early next week.

The low pressure system designated as Invest 91L will move around the southwestern part of a high pressure system that extended from the western Atlantic Ocean to the Gulf of Mexico.  The high pressure system will steer Invest 91L toward the west-northwest during the next 24 hours.  On its anticipated track, the low pressure system designated as Invest 91L will move toward the western Bay of Campeche.

If the second low pressure system over the northwestern Gulf of Mexico interacts with Invest 91L, then the low pressure system designated as Invest 91L could get pulled toward the north during the first half of next week.  If Invest 91L get pulled toward the north, then it would spend more time over water and it would have more time to strengthen.  The low pressure system designated as Invest 91L could affect the coast of Texas and Louisiana in a few days.

Typhoon Yagi Brings Wind and Rain to Northern Vietnam

Typhoon Yagi brought wind and rain to northern Vietnam on Saturday.  At 5:00 a.m. EDT on Saturday the center of Typhoon Yagi was located at latitude 21.1°N and longitude 106.5°E which put the center about 65 miles (105 km) east of Hanoi, Vietnam.  Yagi was moving toward the west-northwest at 16 m.p.h. (26 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. (200 km/h).  The minimum surface pressure was 942 mb.

Typhoon Yagi was the equivalent of a major hurricane when it made landfall on the northern coast of Vietnam near Haiphong.  A small circular eye was present at the center of Yagi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  The strongest winds moved over the coastal regions of northern Vietnam.  Bands of showers and thunderstorms revolved around the core of Yagi’s circulation.  Storms dropped heavy rain on northern Vietnam.

‘Winds to typhoon force extended out 50 miles (80 km) from the center of Typhoon Yagi.  Winds to tropical storm force extended out 180 miles (290 km) from the center of Yagi’s circulation.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 23.6.  The Hurricane Size Index (HII) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 44.2.  Typhoon Yagi was similar in size and intensity to Hurricane Jeanne when Jeanne hit southeast Florida in 2004.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Yagi will move across northern Vietnam.  The center of Typhoon Yagi will pass near Hanoi in a few hours.

Typhoon Yagi will weaken gradually as it moves farther inland over northern Vietnam.  Yagi will bring strong winds and heavy rain to northern Vietnam during the next 24 hours.  Yagi is capable of causing major damage.  Heavy rain will cause floods in many locations.  Widespread outages of electricity are likely.

 

Typhoon Yagi Hits Hainan

Typhoon Yagi hit Hainan on Friday morning.  At 11:00 a.m. EDT on Friday the center of Typhoon Yagi was located at latitude 20.2°N and longitude 109.8°E which put the center about 25 miles (40 km) west of Haikou, China.  Yagi was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 928 mb.

Typhoon Yagi brought strong winds and heavy rain to Hainan on Friday morning.  The core of Typhoon Yagi moved over the northeastern part of Hainan.  A small circular eye was present at the center of Yagi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  The strongest winds moved over the northern coastal regions of Hainan.  Bands of showers and thunderstorms revolved around the core of Yagi’s circulation.  Storms dropped heavy rain on Hainan and southern China.

The formation of concentric eyewalls on Thursday caused the size of Typhoon Yagi’s circulation to increase.  Winds to typhoon force extended out 70 miles (110 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 185 miles (300 km) from the center of Typhoon Yagi.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 28.3.  The Hurricane Size Index (HII) was 24.9 and the Hurricane Wind Intensity Size Index (HWISI) was 53.2.  Typhoon Yagi was similar in size to Hurricane Jeanne when Jeanne hit southeast Florida in 2004.  Yagi was stronger than Jeanne was.

Typhoon Yagi will move through an environment that will be somewhat favorable for intensification during the next 12 hours.  The center of Yagi’s circulation will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, Typhoon Yagi may not intensify during the next 12 hours because the core of Yagi’s circulation was somewhat disrupted as it moved across Hainan.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Yagi will reach northeastern Vietnam in 12 hours.  Typhoon Yagi could still be the equivalent of a major hurricane when it reaches VIetnam.

Typhoon Yagi will continue to produce strong winds and heavy rain in parts of Hainan during the  next few hours.  Yagi will be capable of causing major damage in Hainan.  Heavy rain is likely to cause floods in some locations. Typhoon Yagi will also produce strong winds and heavy rain in parts of southern China.  Yagi will produce strong winds and heavy rain in southwestern Guangdong and Guangxi.  Typhoon Yagi will bring strong winds and heavy rain to northeastern Vietnam during the weekend.  Yagi is likely to cause floods in northeastern Vietnam.  Typhoon Yagi could also cause a storm surge of up to 10 feet (3 meters) along the coast of northeastern Vietnam.

Typhoon Yagi Passes South of Hong Kong

Powerful Typhoon Yagi passed south of Hong Kong on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Yagi was located at latitude 19.3°N and longitude 112.5°E which put the center about 230 miles (370 km) south-southwest of Hong Kong.  Yagi was moving toward the west at 12 m.p.h. (19 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 923 mb.

The inner end of a rainband wrapped around the original eye and eyewall at the core of Typhoon Yagi and concentric eyewalls formed.  The formation of concentric eyewalls ended the intensification of Typhoon Yagi, but Yagi was still the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

A circular eye with a diameter of 23 miles (37 km) was at the center of Yagi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  A second outer ring of thunderstorms surrounded the inner eyewall.  Bands of showers and thunderstorms were revolving around the core of Typhoon Yagi.  Storms near the core of Yagi generated upper level divergence that pumped mass away from the typhoon.

The formation of concentric eyewalls caused the size of Typhoon Yagi’s circulation to increase.  Winds to typhoon force extended out 90 miles (145 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 205 miles (330 km) from the center of Typhoon Yagi.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 31.6.  The Hurricane Size Index (HII) was 24.8 and the Hurricane Wind Intensity Size Index (HWISI) was 56.4.  Typhoon Yagi was similar in intensity to Hurricane Laura when Laura hit southwest Louisiana in 2020.  Yagi is bigger than Laura was.

Typhoon Yagi will move through an environment that will be favorable for intensification during the next 12 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Even though Typhoon Yagi will move through a favorable environment, the concentric eyewalls may prevent Yagi from intensifying.  If the inner eyewalls weakens, then Typhoon Yagi could weaken as well.  If the inner eyewall remains intact, then Typhoon Yagi could intensify during the next few hours.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west during the next 24 hours.  On its anticipated track, the center of Typhoon Yagi will reach northeastern Hainan in 12 hours.  Typhoon Yagi is likely to be the equivalent of a major hurricane when it reaches Hainan.

Typhoon Yagi will bring strong winds and heavy rain to Hainan.  Yagi will be capable of causing major damage in Hainan.  Heavy rain is likely to cause floods in some locations.  Typhoon Yagi could also cause a storm surge of up to 14 feet (4.3 meters) along the coast of northeastern Hainan.  Yagi will also bring strong winds and heavy rain to southwestern Guangdong and Guangxi.

 

Typhoon Yagi Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Yagi rapidly intensified to the equivalent of a major hurricane over the South China Sea on Wednesday.  At 11:00 a.m. EDT on Wednesday the center of Typhoon Yagi was located at latitude 19.2°N and longitude 116.6°E which put the center about 275 miles (445 km) southeast of Hong Kong.  Yagi was moving toward the west at 6 m.p.h. (10 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 968 mb.

Typhoon Yagi rapidly intensified to the equivalent of a majoro hurricane on Wednesday.  A circular eye was visible at the center of Yagi’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 were revolving around the core of Typhoon Yagi.  Storms near the core generated upper level divergence that pumped large amounts of mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Yagi increased in size as Yagi intensified rapidly.  Winds to typhoon force extended out 60 miles (95 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 140 miles (220 km) from the center of Typhoon Yagi.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 23.6.  The Hurricane Size Index (HSI) was 16.2 and the Hurricane Wind Intensity Size Index (HWISI) was 39.8.  Typhoon Yagi was similar in intensity to Hurricane Dennis when Dennis hit Florida in 2005.  Yagi is larger than Dennis was.

Typhoon Yagi will move through an environment that will be very favorable for intensification during the next 24 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Yagi will intensify during the next 24 hours.  Yagi could continue to intensify rapidly during the next few hours.  If the inner end of rainband wraps around the eye and eyewall in the core of Yagi’s circulation, then an eyewall replacement cycle could cause Typhoon Yagi to weaken.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours. On its anticipated track, the center of Typhoon Yagi will be south of Hong Kong in 24 hours.  Yagi will approach Hainan and the coast of southern China in 36 hours.  Typhoon Yagi is likely to be the equivalent of a major hurricane when it approaches Hainan and the coast of southern China.

Typhoon Yagi will bring strong winds and heavy rain to southern China later this week.  Yagi will bring strong winds and heavy rain to Guangdong, Guangxi and Hainan.  Heavy rain is likely to cause floods in some locations.

 

Yagi Strengthens to a Typhoon Southeast of Hong Kong

Former Tropical Storm Yagi strengthened to a typhoon southeast of Hong Kong on Tuesday evening.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Yagi was located at latitude 19.1°N and longitude 117.5°E which put the center about 315 miles (510 km) southeast of Hong Kong.  Yagi was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 977 mb.

Former Tropical Storm Yagi intensified rapidly to a typhoon after it moved over the South China Sea.  A circular eye formed at the center of Yagi’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 were revolving around the core of Typhoon Yagi.  Storms near the core generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Yagi was symmetrical.  Winds to typhoon force extended out 35 miles (55 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 110 miles (185 km) from the center of Typhoon Yagi.

Typhoon Yagi will move through an environment that will be very favorable for intensification during the next 24 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Yagi will intensify during then next 24 hours.  Yagi could intensify rapidly to the equivalent of a major hurricane.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Yagi will be south of Hong Kong in 36 hours.  Yagi will approach Hainan and the coast of southern China in 48 hours.  Typhoon Yagi could be the equivalent of a major hurricane when it approaches Hainan and the coast of southern China.