Tropical Storm Tammy Forms East of the Lesser Antilles

Tropical Storm Tammy formed over the Atlantic Ocean east of the Lesser Antilles on Wednesday afternoon. At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Tammy was located at latitude 13.0°N and longitude 51.7°W which put it about 625 miles (1005 km) east of the Lesser Antilles. Tammy was moving toward the west at 23 m.p.h. (37 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 1007 mb.

Tropical Storm Watches were issued for Barbados, Dominica, Martinique and Guadeloupe.

A low pressure system over the Atlantic Ocean east of the Lesser Antilles strengthened on Wednesday afternoon and the U.S. National Hurricane Center designated the system as Tropical Storm Tammy. The circulation around Tropical Storm Tammy was not well organized. Many of the thunderstorms were occurring in bands in the eastern part of Tammy’s circulation. Bands in the western part of Tropical Storm Tammy consisted primarily of showers and lower clouds. Storms near the center of Tammy’s circulation were beginning to generate upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 140 miles (220 km) in the northeastern quadrant of Tropical Storm Tammy. The winds in the other parts of Tammy were blowing at less than tropical storm force.

Tropical Storm Tammy will move through an environment somewhat favorable for intensification during the next 24 hours. Tammy will move over water where the Sea Surface Temperatures are near 30°C. It will move under the far eastern part of an upper level low over the Eastern Caribbean Sea. The upper level low will produce southwesterly winds that will blow toward the top of Tammy’s circulation. The winds in the lower levels of the atmosphere are blowing from the east. The difference in wind direction between the upper and lower levels of the atmosphere will cause moderate vertical wind shear. The wind shear will inhibit intensification. Tropical Storm Tammy could intensify a little during the next 24 hours, if the winds in the lower levels weaken. However, if the winds in the lower levels get stronger, then Tammy could weaken to a tropical depression.

Tropical Storm Tammy will move south of a subtropical high pressure system over the Atlantic Ocean. The high pressure system will steer Tammy toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Storm Tammy could be near Barbados in 36 hours.

Tropical Storm Tammy is likely to bring gusty winds and locally heavy rain to Barbados, Dominica, Martinique and Guadeloupe. Heavy rain is likely to cause flash in some locations.

Tropical Storm Sanba Forms East of Vietnam

Tropical Storm Sanba formed over the Gulf of Tonkin east of Vietnam on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Sanba was located at latitude 18.9°N and longitude 108.2°E which put it about 180 miles (280 km) southeast of Haiphong, Vietnam. Sanba was moving toward the northwest 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 1003 mb.

A low pressure system over the Gulf of Tonkin east of Vietnam strengthened on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Sanba. The distribution of thunderstorms in Tropical Storm Sanba was asymmetrical. Many of the thunderstorms were occurring in bands in the eastern side of Sanba’s circulation. Bands in the western part of Tropical Storm Sanba consisted primarily of showers and lower clouds. Storms near the center of Sanba’s circulation generated upper level divergence that pumped mass away to the west and north of the tropical storm. Winds to tropical storm force extended out 50 miles (80 km) in the eastern side of Tropical Storm Sanba. The winds in the western part of Sanba’s circulation were blowing at less than tropical storm force.

Tropical Storm Sanba will move through an environment somewhat favorable for intensification during the next 24 hours. Sanba will move over water where the Sea Surface Temperatures are near 28°C. It will move under the western part of an upper level ridge centered northwest of the Philippines. The upper level ridge will produce southeasterly winds that will blow toward the top of Sanba’s circulation. Those winds will cause some vertical wind shear but the wind shear will not be strong enough to prevent intensification. Some of the air circulating around the eastern side of Tropical Storm Sanba will flow over Hainan. The additional friction caused by the land will cause the air in that part of Sanba’s circulation to slow down. Tropical Storm Sanba could intensify gradually during the next 24 hours.

Tropical Storm Sanba will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Sanba toward the north-northwest during the next 24 hours. On its anticipated track the center of Tropical Cyclone Sanba will pass west of Hainan. Sanba will move toward northeastern Vietnam.

Bands in the eastern side of Tropical Storm Sanba are already producing gusty winds and locally heavy rain in parts of Hainan. Bands in the western side of Sanba’s circulation are bringing rain showers to parts of northern Vietnam. Tropical Storm Sanba will continue to produce gusty winds and locally heavy rain in parts of Hainan and northern Vietnam. Heavy rain could cause flash floods in some locations.

Tropical Storm Norma Forms South of Baja California

Tropical Storm Norma formed over the Eastern North Pacific Ocean south of Baja California on Tuesday afternoon. At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Norma was located at latitude 13.2°N and longitude 107.3°W which put it about 690 miles (1110 km) south-southeast of Cabo San Lucas, Mexico. Norma was moving toward the west-northwest at 10 m.p.h. (16 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 1004 mb.

A low pressure system over the Eastern North Pacific Ocean south of Baja California strengthened on Tuesday and the U.S. National Hurricane Center designated the system as Tropical Storm Norma. The circulation around Tropical Storm Norma exhibited more organization on Tuesday afternoon. Bands of showers and thunderstorms were revolving around the center of Norma’s circulation. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 140 miles (220 km) in the northern side of Tropical Storm Norma. Winds in the southern side of Norma’s circulation were blowing at less than tropical storm force.

Tropical Storm Norma will move through an environment favorable for intensification during the next 36 hours. Norma will move over water where the Sea Surface Temperatures are near 27°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Norma will intensify during the next 36 hours. Norma could strengthen to a hurricane within 36 hours. Tropical Storm Norma could start to intensify rapidly after an inner core with an eye and eyewall develop.

Tropical Storm Norma will move around the southwestern part of a high pressure system over Mexico. The high pressure system will steer Norma toward the northwest during the next 24 hours. Tropical Storm Norma will move more toward the north later this week when it moves around the western end of the high pressure system. On its anticipated track Norma could approach the southern end of Baja California during the weekend. Norma is likely to be a hurricane when it approaches Baja California.

Sean Weakens to a Tropical Depression

Former Tropical Storm weakened to a tropical depression east of the Leeward Islands on Saturday. At 11:00 a.m. EDT on Saturday the center of Tropical Depression Sean was located at latitude 16.0°N and longitude 44.2°W which put it about 1255 miles (2020 km) east of the Northern Leeward Islands. Sean was moving toward the northwest at 8 m.p.h. (13 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 1007 mb.

Former Tropical Storm Sean weakened slowly during the past 36 hours and the U.S. National Hurricane Center downgraded Sean to a tropical depression on Saturday morning. A few more thunderstorms developed near the center of Sean’s circulation after it was downgraded to a tropical depression. There were also a few more thunderstorms in bands revolving around the center of Tropical Depression Sea. However, some bands still consisted primarily of showers and lower clouds.

Tropical Depression Sean will move through an environment mostly unfavorable for intensification during the next 24 hours. Sean will move over water where the Sea Surface Temperatures are near 28°C. It will move under the southern side of an upper level ridge over the eastern Atlantic Ocean. The upper level ridge will produce northeasterly winds that will blow toward the top of Sean’s circulation. Those winds will cause moderate vertical wind shear. Tropical Depression Sean will move into an area where there is drier air. The vertical wind shear and the drier air are likely to cause Tropical Depression Sean to weaken during the next 24 hours.

Tropical Depression Sean will move around the southwestern part of a high pressure system that extends from West Africa to the central Atlantic Ocean. The high pressure system will steer Sean toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Depression Sean will remain far east of the Northern Leeward Islands.

Typhoon Bolaven Passes East of Iwo To

Typhoon Bolaven passed east of Iwo To on Thursday evening. At 11:00 p.m. EDT on Thursday the center of Typhoon Bolaven was located at latitude 26.2°N and longitude 147.8°E which put it about 350 miles (570 km) east of Iwo To. Bolaven was moving toward the northeast at 23 m.p.h. (37 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. (285 km/h). The minimum surface pressure was 928 mb.

Concentric eyewalls developed at the center of Typhoon Bolaven on Thursday. The inner end of a rainband wrapped around the existing small eye and eyewall. The larger outer eyewall surrounded the inner eye and eyewall. Bands of showers and thunderstorms revolved around the concentric eyewalls. Storms near the eyewalls generated upper level divergence that pumped mass away to the northeast of the typhoon.

The size of Typhoon Bolaven increased when the concentric eyewalls developed. Winds to typhoon force extended out 60 miles (95 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 265 miles (425 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 29.9. The Hurricane Size Index (HSI) was 21.3 and the Hurricane Wind Intensity Size Index (HWISI) was 51.2.

Typhoon Bolaven will move through an environment that will become more unfavorable for a powerful typhoon during the next 24 hours. Bolaven will move over water where the Sea Surface Temperatures are near 27°C. It will move under the eastern side of an upper level trough near Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Bolaven’s circulation. Those winds will cause the vertical wind shear to increase. Typhoon Bolaven is likely to weaken during the next 24 hours as it goes through an eyewall replacement cycle and the vertical wind shear increases. Bolaven could make a transition to a strong extratropical cyclone when it moves over cooler water south of Alaska.

The upper level trough near Japan will steer Typhoon Bolaven quickly toward the northeast during the next 24 hours. On its anticipated track, Typhoon Bolaven will pass far to the east of Japan on Friday. Bolaven could move south of the Aleutian Islands during the weekend.

Tropical Storm Sean Moves West of Cabo Verde Islands

Tropical Storm Sean moved west of the Cabo Verde Islands on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Sean was located at latitude 13.8°N and longitude 38.2°W which put it about 960 miles (1545 km) west of the Cabo Verde Islands. Sean was moving toward the northwest at 12 m.p.h. (19 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 1006 mb.

Tropical Storm Sean did not change much on Thursday. An upper level trough over the central Atlantic Ocean was producing southwesterly winds that were blowing toward the top of Sean’s circulation. Those winds were causing strong vertical wind shear. The wind shear was causing the distribution of thunderstorms in Tropical Storm Sean to be asymmetrical. Thunderstorms were occurring in bands in the northeastern quadrant of Sean’s circulation. Bands in the other parts of Tropical Storm Sean consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 105 miles (165 km) in the northeastern quadrant of Tropical Storm Sean. The winds in the other parts of Sean’s circulation were blowing at less than tropical storm force.

Tropical Storm Sean will move through an environment marginally favorable for intensification during the next 24 hours. Sean will move over water where the Sea Surface Temperatures are near 28°C. It will continue to move under the eastern side of an upper level trough over the central Atlantic Ocean. The upper level trough will continue to strong vertical wind shear. The wind shear is likely to inhibit intensification. Tropical Storm Sean could maintain its intensity during the next 24 hours.

Tropical Storm Sean will move around the southwestern part of a high pressure system that extends from West Africa to the eastern Atlantic Ocean. The high pressure system will steer Sean toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Sean will move farther away from the Cabo Verde Islands.

Typhoon Bolaven Gets Even Stronger

Typhoon Bolaven got even stronger on Wednesday morning. At 11:00 a.m. EDT on Wednesday the center of Typhoon Bolaven was located at latitude 19.3°N and longitude 142.9°E which put it about 420 miles (675 km) south-southeast of Iwo To. Bolaven was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 180 m.p.h. (290 km/h) and there were wind gusts to 220 m.p.h. (355 km/h). The minimum surface pressure was 904 mb.

Typhoon Bolaven grew even more powerful on Wednesday morning. A circular eye with a diameter of 16 miles (26 km) was at the center of Bolaven’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 Bolaven. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass caused the surface pressure to decrease to 904 mb.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 45 miles (65 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 195 miles (315 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 42.2. The Hurricane Size Index (HSI) was 18.4 and the Hurricane Wind Intensity Size Index (HWISI) was 60.6. Typhoon Bolaven was similar in intensity to Hurricane Dorian in 2019. Bolaven was bigger than Dorian was.

Typhoon Bolaven will move through an environment favorable for a very powerful typhoon during the next 24 hours. Bolaven 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. Typhoon Bolaven could maintain its intensity during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

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

Tropical Storm Sean Forms over the Eastern Atlantic Ocean

Tropical Storm Sean formed over the eastern Atlantic Ocean on Wednesday morning. At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Sean was located at latitude 10.3°N and longitude 33.1°W which put it about 725 miles (1170 km) west-southwest of the Cabo Verde Islands. Sean was moving toward the west-northwest at 13 m.p.h. (21 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 1006 mb.

A low pressure system over the Atlantic Ocean west-southwest of Cabo Verde Islands strengthened on Wednesday morning and the U.S. National Hurricane Center designated the system as Tropical Storm Sean. More thunderstorms began to form near the center of Sean’s circulation. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away to the north of the tropical storm. Winds to tropical storm force extended out 90 miles (145 km) in the northeastern quadrant of Tropical Storm Sea. The winds in the other parts of Sean’s circulation were blowing at less than tropical storm force.

Tropical Storm Sean will move through an environment somewhat favorable for intensification during the next 24 hours. Sean will move over water where the Sea Surface Temperatures are near 29°C. It will move under the eastern side of an upper level trough over the central Atlantic Ocean. The upper level trough will produce southerly winds that will blow toward the top of Sean’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear may not be strong enough to prevent intensification. Tropical Storm Sean is likely to intensify during the next 24 hours.

Tropical Storm Sean will move around the southwestern part of a high pressure system that extends from West Africa to the eastern Atlantic Ocean. The high pressure system will steer Sean toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Storm Sean will move farther away from the Cabo Verde Islands.

Typhoon Bolaven Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Tuesday evening. At 11:00 p.m. EDT on Tuesday the center of Typhoon Bolaven was located at latitude 17.5°N and longitude 143.8°E which put it about 245 miles (390 km) north-northwest of Guam. Bolaven was moving toward the north-northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 920 mb.

Typhoon Warnings were in effect for Rota, Tinian and Saipan. Tropical Storm Warnings were in effect for Agrihan, Pagan and Alamagan.

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane west of the Marianas on Tuesday evening. A small circular eye with a diameter of 14 miles (22 km) was at the center of Bolaven’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 Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 25 miles (40 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 35.0. The Hurricane Size Index (HSI) was 11.5 and the Hurricane Wind Intensity Size Index (HWISI) was 46.5.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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. Typhoon Bolaven could continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north-northwest during the next 24 hours. On its anticipated track, the Typhoon Bolaven will stay west of the Marianas during the next 24 hours.

Hurricane Lidia Hits Mexico Near Puerto Vallarta

Powerful Hurricane Lidia hit the coast of Mexico near Puerto Vallarta on Tuesday evening. At 8:00 p.m. EDT on Tuesday the center of Hurricane Lidia was located at latitude 20.1°N and longitude 105.5°W which put it about 35 miles (55 km) south-southwest of Puerto Vallarta, Mexico. Lidia was moving toward the east-northeast at 16 m.p.h. (26 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 942 mb.

A Hurricane Warning was in effect for the portion of the coast from Manzanillo to El Roblito, Mexico. A Hurricane Warning was in effect for Las Islas Marias. A Tropical Storm Warning was in effect for the portion of the coast from El Roblito to Mazatlan, Mexico. A Tropical Storm Warning was also in effect for the portion of the coast from Manzanillo to Punta San Telmo, Mexico.

Hurricane Lidia rapidly intensified to Category 4 on the Saffir-Simpson Scale prior to making landfall on the west coast of Mexico. Winds to hurricane force extended out 30 miles (50 km) from the center of Lidia. Winds to tropical storm force extended out 140 miles (220 km) from the center of circulation. The Hurricane Intensity Index (HII) was 28.3. The Hurricane Size Index (HSI) was 9.8 and the Hurricane Wind Intensity Size Index (HWISI) was 38.1. Hurricane Lidia was similar in size and intensity to Hurricane Charley when Charley hit Southwest Florida in 2004.

An upper level trough west of Baja California will steer Hurricane Lidia toward the northeast during the next 24 hours. On its anticipated track, Hurricane Lidia will move quickly inland over Jalisco. Lidia will weaken steadily as it moves farther inland. Even though it will weaken, Hurricane Lidia be capable of causing severe damage. Lidia will bring strong, gusty winds and locally heavy rain. Regional outages of electricity are likely. Heavy rain will fall in Jalisco and Nayarit. The heavy rain is likely to cause flash floods in some locations. Hurricane Lidia could cause a storm surge of up to 13 feet (4 meters) along the coast of Jalisco.