Tag Archives: HWISI

Typhoon Halong Intensifies to Equivalent of a Major Hurricane

Typhoon Halong intensified to the equivalent of a major hurricane over the Western North Pacific Ocean south of Japan on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Halong was located at latitude 28.4°N and longitude 137.2°E which put the center about 490 miles (785 km) south-southwest of Tokyo, Japan.  Halong was moving toward the 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 942 mb.

Typhoon Halong intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Tuesday morning.  A circular eye with a diameter of 40 miles (65 km) was at the center of Halong’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 Halong.  Storms near the core of Halong generated upper level divergence that pumped mass away from the typhoon in all directions.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Halong was relatively small.  Winds to typhoon force extended out 30 miles (50 km) from the center of Halong’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Halong.

The Hurricane Intensity Index (HII) for Typhoon Halong was 25.1.  The Hurricane Size Index (HSI) was 10.2 and the Hurricane Wind Intensity Size Index (HWISI) was 35.3.  Typhoon Halong was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon Halong will move through an environment that is favorable for intensification during the next 24 hours.  Halong 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 south of Japan.  The upper level winds are weak near the middle of the upper level ridge and there will be little vertical wind shear.  Typhoon Halong will intensify during the next 24 hours.

Typhoon Halong will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Halong toward the north during the next 24 hours.  On its anticipated track, Typhoon Halong will move closer to Honshu.

Typhoon Matmo Brings Wind and Rain to Southern China

Typhoon Matmo brought wind and rain to southern China on Sunday morning.  At 5:00 a.m. EDT on Sunday the center of Typhoon Matmo was located at latitude 21.1°N and longitude 110.0°E which put the center about 25 miles (40 km) west of Zhanjiang, China.  Matmo was moving toward the west-northwest at 14 m.p.h. (25 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 966 mb.

Typhoon Matmo strengthened to the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale before it made landfall on the coast of southern China on Sunday morning.  The center of Matmo made landfall near Zhanjiang.

Typhoon Matmo was a large typhoon at the time of landfall.  Winds to typhoon force extended out 70 miles (110 km) from the center of Matmo’s circulation.  Winds to tropical storm force extended out 175 miles (280 km) from the center of Typhoon Matmo.

The Hurricane Intensity Index (HII) for Typhoon Matmo was 17.8.  The Hurricane Size Index (HSI) was 23.2 and the Hurricane Wind Intensity Size index (HWISI) was 41.0.  Typhoon Matmo was similar in size and intensity to Hurricane Gustav when Gustav hit Louisiana in 2008.

Typhoon Matmo will move around the southern side of a high pressure system that is over southern China.  The high pressure system will steer Matmo toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Matmo will move inland near the coast of southern China.

Typhoon Matmo will bring strong winds and heavy rain to southwestern Guangdong, Guangxi, and Hainan.  Heavy rain is likely to cause floods in some locations.  Matmo could also cause a storm surge of up to 10 feet (3 meters) along parts of the coast.  Typhoon Matmo will drop heavy rain on parts of northern Vietnam early next week.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression 28W strengthened to Tropical Storm Halong east of Iwo To.  At 5:00 a.m. EDT on Sunday the center of Tropical Storm Halong was located at latitude 25.0°N and longitude 142.0°E which put the center about 65 miles (105 km) east of Iwo To.   Halong was moving toward the west-northwest at 5 m.p.h. (8 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 994 mb.

Hurricane Imelda Brings Wind and Rain to Bermuda

Hurricane Imelda brought wind and rain to Bermuda on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Imelda was located at latitude 32.1°N and longitude 65.0°W which put the center about 20 miles (30 km) southwest of Bermuda.  Imelda was moving toward the east-northeast at 29 m.p.h. (46 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 971 mb.

A Hurricane Warning is in effect for Bermuda.

Hurricane Imelda was in the middle of a transition to an extratropical cyclone when it reached Bermuda on Wednesday night.  The transition to an extratropical cyclone affected the structure of Hurricane Imelda.  Thunderstorms were occurring in bands in the northern side of Imelda’s circulation.  The bands in the southern half of Hurricane Imelda consisted primarily of showers and lower clouds.

The size of the circulation around Hurricane Imelda increased during the transition to an extratropical cyclone.  Winds to hurricane force extended out 45 miles (75 km) from the center of Imelda’s circulation.  Winds to tropical storm force extended out 250 miles (400 km) from the center of Hurricane Imelda.

The Hurricane Intensity Index (HII) for Hurricane Imelda was 16.5. The Hurricane Size Index (HSI) was 15.6 and the Hurricane Wind Intensity Size Index (HWISI) was 32.1.

Hurricane Imelda will continue to bring strong winds and heavy rain to Bermuda during the next few hours. The strong winds could cause electricity outages.  Heavy rain could cause flooding.

Hurricane Imelda will move through an environment unfavorable for intensification of a hurricane during the next 24 hours.  Imelda will move over water where the Sea Surface Temperatures are near 27°C.  It will move under the southern side of an upper level trough that is east of the U.S.  The upper level trough will produce strong southwesterly winds that will blow toward the top of Imelda’s circulation.  Those winds will cause strong vertical wind shear.  The strong vertical wind shear will cause Hurricane Imelda to complete a transition to a strong extratropical cyclone on Thursday.

The upper level trough east of the U.S. will steer Hurricane Imelda toward the east-northeast during the next 24 hours.  On its anticipated track, Hurricane Imelda will move quickly away from Bermuda on Thursday.

Hurricane Imelda Strengthens to Cat. 2

Hurricane Imelda strengthened to Category 2 on the Saffir-Simpson Scale on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Hurricane Imelda was located at latitude 31.0°N and longitude 70.4°W which put the center about 340 miles (550 km) west-southwest of Bermuda.  Imelda was moving toward the east-northeast at 20 m.p.h. (32 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 966 mb.

A Hurricane Warning is in effect for Bermuda.

Hurricane Imelda strengthened to Category 2 on the Saffir-Simpson Scale on Wednesday morning.  A circular eye with a diameter of 15 miles (24 km) was at the center of Imelda’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 Hurricane Imelda.  Storms near the core of Imelda generated upper level divergence that pumped mass away to the north and east of the hurricane.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Hurricane Imelda increased when Imelda strengthened.  Winds to hurricane force extended out 60 miles (95 km) from the center of Imelda’s circulation.  Winds to tropical storm force extended out 230 miles (370 km) from the center of Hurricane Imelda.

The Hurricane Intensity Index (HII) for Hurricane Imelda was 16.5.  The Hurricane Size Index (HSI) was 19.4 and the Hurricane Wind Intensity Size Index (HWISI) was 34.9.

Hurricane Imelda will move through an environment somewhat favorable for intensification during the next 24 hours.  Imelda will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the eastern side of an upper level trough that is over the eastern U.S.  The upper level trough will produce southwesterly winds that will blow toward the top of Imelda’s circulation.  Those winds will cause moderate vertical wind shear.  The moderate vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Hurricane Imelda is likely to intensify during the next 24 hours. Imelda could intensify to a major hurricane.

The upper level trough over the eastern U.S. will steer Hurricane Imelda toward the east-northeast during the next 24 hours.  On its anticipated track, Hurricane Imelda will hit Bermuda on Wednesday night.

Hurricane Imelda will bring strong winds and heavy rain to Bermuda.  The strong winds could cause electricity outages.  Heavy rain could cause flooding.

Elsewhere over the Atlantic Ocean, former Hurricane Humberto merged with a front and made a transition to an extratropical cyclone.  At 11:00 a.m. EDT on Wednesday the center of former Hurricane Humberto was located at latitude 37.0°N and longitude 63.0°W which put the center about 340 miles (550 km) north-northeast of Bermuda.  Humberto was moving toward the east-northeast at 23 m.p.h. (37 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 980 mb.

Hurricane Humberto Intensifies to Cat. 5

Hurricane Humberto intensified to Category 5 on the Saffir-Simpson Scale south of Bermuda on Saturday afternoon.  At 5:00 p.m. EDT on Saturday the center of Hurricane Humberto was located at latitude 22.9°N and longitude 61.1°W which put the center about 685 miles (1105 km) south-southeast of Bermuda.  Humberto was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 925 mb.

Hurricane Humberto intensified to Category 5 on the Saffir-Simpson Scale on Saturday afternoon.  A circular eye with a diameter of 12 miles (19 km) was at the center of Humberto’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 center of Hurricane Humberto.  Storms near the center of Humberto generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large quantities of mass caused the surface pressure to decrease rapidly.

The circulation around Hurricane Humberto was very symmetrical.  Winds to hurricane force extended out 25 miles (40 km) from the center of Humberto’s circulation.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Hurricane Humberto.

The Hurricane Intensity Index (HII) for Hurricane Humberto is 35.0.  The Hurricane Size Index (HSI) is 10.7 and the Hurricane Wind Intensity Size Index (HWISI) is 45.7.  Hurricane Humberto is similar in intensity to Hurricane Michael when Michael hit Northwest Florida in 2018.  Humberto is slightly smaller than Michael was.

Hurricane Humberto will move through an environment favorable for an intense hurricane during the next 24 hours.  Humberto 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 the will be little vertical wind shear.  Hurricane Humberto could intensify during the next 24 hours.  However, the inner end of a rainband is likely to wrap around the existing eye and eyewall.  The formation of concentric eyewalls would start an eyewall replacement cycle.  An eyewall replacement cycle would cause Humberto to weaken, at least temporarily.

Hurricane Humberto will move around the western part of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Humberto toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Humberto will pass far to the south of Bermuda on Sunday.

Elsewhere over the Atlantic Ocean, Tropical Depression Nine formed north of eastern Cuba.  At 5:00 p.m. EDT on Saturday the center of Tropical Depression Nine was located at latitude 22.2°N and longitude 76.5°W which put the center about 215 miles (345 km) south-southeast of Nassau,, Bahamas.  The tropical depression was moving toward the northwest at 5 m.p.h. (8 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.

Tropical Storm Warnings were in effect for the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador.

Tropical Storm Warnings were in effect for the Northwestern Bahamas including Eleuthera, New Providence, the Abacos, the Berry Islands, Andros Island, and Grand Bahama Island.

A Tropical Storm Watch was in effect for the portion of the coast from the Palm Beach/Martin County Line to the Flagler/Volusia County Line, Florida.

Typhoon Ragasa Makes Landfall in Southern China

Typhoon Ragasa made landfall on the coast of southern China east of Yangjiang on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Typhoon Ragasa was located at latitude 21.9°N and longitude 110.5°E which put the center about 30 miles (50 km) northeast of Yangjiang, China.  Ragasa was moving toward the west at 16 m.p.h. (26 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 96 mb.

The center of Typhoon Ragasa made landfall on the coast of southern China east of Yangjiang on Wednesday morning.  Ragasa was a large and powerful typhoon at the time of landfall.  Winds to typhoon force extended out 60 miles (95 km) from the center of Ragasa’s circulation.  Winds to tropical storm force extended out 190 miles (305 km) from the center of Typhoon Ragasa.

The Hurricane Intensity Index (HII) for Typhoon Ragasa was 13.9.  The Hurricane Size Index (HSI) was 20.8 and the Hurricane Wind Intensity Size Index (HWISI) was 34.7.

Typhoon Ragasa will move around the southern side of a high pressure system over China.  The high pressure system will steer Ragasa toward the west during the next 24 hours.  On its anticipated track, the center of Typhoon Ragasa will move westward near the coast of southern China.  Ragasa will move over northern Vietnam on Thursday.

Typhoon Ragasa will bring strong winds and heavy rain to Guangxi, western Guangdong, and northern Hainan.  Heavy rain is likely to cause floods in some locations.  Typhoon Ragasa could cause a storm surge of up to 10 feet (3 meters) along portions of the coast.  Ragasa could also drop heavy rain on parts of northern Vietnam and northern Laos.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Bualoi was strengthening east of the Philippines and Tropical Storm Neoguri was spinning far to the east of Japan.

At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Bualoi was located at latitude 10.6°N and longitude 130.5°E which put the center about 375 miles (605 km) east-southeast of Tacloban, Philippines.  Bualoi was moving toward the west-northwest at 11 m.p.h. (17 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 994 mb.

At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Neoguri was located at latitude 31.2°N and longitude 156.8°E which put the center about 1060 miles (1710 km) east-southeast of Tokyo, Japan.  Neoguri was moving toward the east-northeast at 16 m.p.h. (26 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 980 mb.

Hurricane Warning for Azores for Gabrielle

A Hurricane Warning is in effect for all of the Azores for Hurricane Gabrielle.  At 8:00 a.m. EDT on Wednesday the center of Hurricane Gabrielle was located at latitude 35.8°N and longitude 50.2°W which put the center about 1285 miles (2070 km) west of the Azores.  Gabrielle was moving toward the east-northeast at 25 m.p.h. (40 km/h).  The maximum sustained wind speed was 115 m.p.h. (1850 km/h) and there were wind gusts to 135 m.p.h. (220 km/h).  The minimum surface pressure was 960 mb.

A Hurricane Warning is in effect for all of the Azores.

Hurricane Gabrielle was speeding toward the Azores on Wednesday morning.  Gabrielle was still a major hurricane.  An eye was still present at the center of Gabrielle’s circulation, but there were some clouds in the eye.  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 Gabrielle’s circulation.  Storms near the center of Gabrielle generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper level was slightly less than the inflow of mass in the lower levels of the atmosphere.  The stronger inflow of mass in the lower levels caused the surface pressure to increase gradually.

The size of the circulation around Hurricane Gabrielle did not change much during the past 24 hours.  Winds to hurricane force extended out 45 miles (75 km) from the center of Gabrielle’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Hurricane Gabrielle.

The Hurricane Intensity Index (HII) for Hurricane Gabrielle is 20.6.  The Hurricane Size Index (HSI) is 15.5 and the Hurricane Wind Intensity Size Index (HWISI) is 36.1. Hurricane Gabrielle is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Hurricane Gabrielle will move through an environment that will be unfavorable for intensification of a hurricane during the next 24 hours.  Gabrielle will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the southern extent of the upper level westerly winds in the middle latitudes.  Those upper level westerly winds will cause moderate vertical wind shear.  Hurricane Gabrielle will continue to weaken gradually during the next 24 hours.

The upper level westerly winds in the middle latitudes will steer Hurricane Gabrielle toward the east during the next 24 hours.  On its anticipated track, Hurricane Gabrielle will reach the Azores on Thursday.

Hurricane Gabrielle will bring strong winds and heavy rain to the Azores on Thursday night and Friday.

Typhoon Ragasa Brings Wind and Rain to Hong Kong

Typhoon Ragasa brought wind and rain to Hong Kong on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Ragasa was located at latitude 21.3°N and longitude 113.2°E which put the center about 80 miles (130 km) south-southwest of Hong Kong.  Ragasa was moving toward the west at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 944 mb.

The center of Typhoon Ragasa passed south of Hong Kong on Tuesday night.  A weather station at the airport in Hong Kong (VHHH) reported a sustained wind speed of 47 kt (54 m.p.h. or 87 km/h) and a wind gust of 66 kt (76 m.p.h. or 122 km/h).

The inner end of a rainband wrapped around the existing eye and eyewall in Typhoon Ragasa as it was passing south of Hong Kong.  A second outer eyewall appeared to be developing.  The formation of concentric eyewalls could start another eyewall replacement cycle.  Bands of showers and thunderstorms were revolving around the core of Typhoon Ragasa.  Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Ragasa was large.  Winds to typhoon force extended out 60 miles (95 km) from the center of Ragasa’s circulation.  Winds to tropical storm force extended out 190 miles (305 km) from the center of Typhoon Ragasa.

The Hurricane Intensity Index (HII) for Typhoon Ragasa is 25.1.  The Hurricane Size Index (HSI) is 20.8 and the Hurricane Wind Intensity Size Index (HWISI) is 45.9.  Typhoon Ragasa is similar in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Ragasa is larger than Harvey was.

Typhoon Ragasa will move through an environment that will be favorable for a powerful typhoon during the next few hours.  Ragasa 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.  Even though Typhoon Ragasa will move through a favorable environment, another eyewall replacement cycle would cause Ragasa to weaken.

Typhoon Ragasa will move around the southern side of a high pressure system over China.  The high pressure system will steer Ragasa toward the west during the next 24 hours.  On its anticipated track, the center of Typhoon Ragasa will make landfall on the coast of southern China west of Macau in 12 hours.

Typhoon Ragasa will bring strong winds and heavy rain to Guangxi and to western Guangdong.  Heavy rain is likely to cause floods in some locations.  Typhoon Ragasa could cause a storm surge of up to 13 feet (4 meters) along portions of the coast.  Ragasa could also drop heavy rain over northern parts of Vietnam and Laos.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Bualoi formed east of the Philippines and former Typhoon Neoguri weakened to a tropical storm far to the east of Japan.

At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Bualoi was located at latitude 9.5°N and longitude 133.4°E which put the center about 535 miles (865 km) east of Surigao, Philippines.  Bualoi was moving toward the west-southwest 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 1002 mb.

At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Neoguri was located at latitude 30.6°N and longitude 154.6°E which put the center about 910 miles (1465 km) east-southeast of Tokyo, Japan.  Neoguri was moving toward the east at 6 m.p.h. (10 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 978 mb.

Gabrielle Prompts Hurricane Watch for the Azores

The risk posed by Hurricane Gabrielle prompted the issuance of a Hurricane Watch for the Azores on Tuesday.  At 2:00 p.m. EDT on Tuesday the center of Hurricane Gabrielle was located at latitude 34.3°N and longitude 57.5°W which put the center about 1710 miles (2755 km) west of the Azores.  Gabrielle was moving toward the east-northeast at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 952 mb.

A Hurricane Watch is in effect for all of the Azores.

A circular eye with a diameter of 20 miles (32 km) was at the center of Gabrielle’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 center of Gabrielle’s circulation.  Storms near the center of Gabrielle generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper level was slightly less than the inflow of mass in the lower levels of the atmosphere.  The strong inflow of mass in the lower levels caused the surface pressure to increase gradually.

The size of the circulation around Hurricane Gabrielle did not change much during the past 24 hours.  Winds to hurricane force extended out 40 miles (65 km) from the center of Gabrielle’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) in the western side of Hurricane Gabrielle.  Winds to tropical storm force extended out 70 miles (110 km) in the eastern side of Gabrielle’s circulation.

The Hurricane Intensity Index (HII) for Hurricane Gabrielle was 25.1.  The Hurricane Size Index (HSI) was 12.9 and the Hurricane Wind Intensity Size Index (HWISI) was 38.0.  Hurricane Gabrielle was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Hurricane Gabrielle will move through an environment that will become more unfavorable for intensification during the next 24 hours.  Gabrielle will move over water where the Sea Surface Temperatures are near 27°C.  It will move under the southern extent of the upper level westerly winds in the middle latitudes.  Those upper level westerly winds will cause the vertical wind shear to increase.  Hurricane Gabrielle will continue to weaken gradually during the next 24 hours.

The upper level westerly winds in the middle latitudes will steer Hurricane Gabrielle toward the east during the next 24 hours.  On its anticipated track, Hurricane Gabrielle will reach the Azores on Thursday.

Hurricane Gabrielle will bring strong winds and heavy rain to the Azores on Thursday night and Friday.

Typhoon Ragasa Moves over South China Sea

Typhoon Ragasa moved over the South China Sea on Monday night.  At 11:00 p.m. EDT on Monday the center of Typhoon Ragasa was located at latitude 20.2°N and longitude 117.7°E which put the center about 300 miles (485 km) east-southeast of Hong Kong.  Ragasa was moving toward the west at 13 m.p.h. (21 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 930 mb.

Typhoon Ragasa went through an eyewall replacement cycle, but the eyewall replacement only weakened Ragasa slightly.  A new eye with a diameter of 30 miles (50 km) was at the center of Ragasa’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 center of Typhoon Ragasa.  Storms near the center of Ragasa generated strong upper level divergence that pumped mass away in all directions from the typhoon.  The removal of large quantities of mass in the upper levels was slightly less than the inflow of mass in the lower levels of the atmosphere.  The inflow of mass in the lower levels caused the surface pressure to increase slowly.

The circulation around Typhoon Ragasa was large.  Winds to typhoon force extended out 80 miles (130 km) from the center of Ragasa’s circulation.  Winds to tropical storm force extended out 240 miles (390 km) from the center of Typhoon Ragasa.

The Hurricane Intensity Index (HII) for Typhoon Ragasa was 29.9.  The Hurricane Size Index (HSI) was 28.7 and the Hurricane Wind Intensity Size Index (HWISI) was 58.6.  Typhoon Ragasa was larger and stronger than Hurricane Helene was when Helene hit Florida in 2024.

Typhoon Ragasa will move through an environment that will be favorable for a powerful typhoon during the next 24 hours.  Ragasa 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 over China.  The upper level ridge will produce easterly winds that will blow toward the top of Ragasa’s circulation.  Those winds will cause the vertical wind shear to increase.  Typhoon Ragasa could weaken slowly during the next 24 hours because of more vertical wind shear.

Typhoon Ragasa will move around the southern side of a high pressure system over China.  The high pressure system will steer Ragasa toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Ragasa will be just south of Hong Kong in less than 24 hours.

Typhoon Ragasa will bring strong winds and locally heavy rain to coastal regions in southern China including Hong Kong.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Ragasa could also cause a storm surge of up to 13 feet (4 meters) along parts of the coast.

Elsewhere over the Western North Pacific Ocean, Typhoon Neoguri moved farther east of Japan.  At 11:00 p.m. EDT on Monday the center of Typhoon Neoguri was located at latitude 30.6°N and longitude 153.3°E which put the center about 910 miles (1470 km) east of Tokyo, Japan.  Neoguri was moving toward the east-northeast at 11 m.p.h. (17 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 963 mb.