Category Archives: Tropical Cyclones

Information about tropical cyclones

Tropical Depression Two Strengthens to Tropical Storm Bill

Former Tropical Depression Two strengthened to Tropical Storm Bill east-northeast of Cape Hatteras on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Bill was located at latitude 36.7°N and longitude 69.8°W which put it about 335 miles (540 km) east-northeast of Cape Hatteras, North Carolina. Bill was moving toward the northeast at 23 m.p.h. (37 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1003 mb.

The circulation around former Tropical Depression Two intensified on Monday night and the National Hurricane Center upgraded the system to Tropical Storm Bill. Even though the circulation around Bill was stronger, the distribution of thunderstorms was asymmetrical. The strongest thunderstorms were occurring in bands on the eastern side of Tropical Storm Bill. Bands on the western side of Bill consisted mainly of showers and lower clouds. Winds to tropical storm force extended out 70 miles (110 km) in the southeastern quadrant of Tropical Storm Bill. The wind was blowing at less than tropical storm force in the other quadrants of Bill. An upper level trough east of the Great Lakes was producing strong southwesterly winds that were blowing toward the top of Tropical Storm Bill. Those winds were causing moderate vertical wind shear and they were the cause of the asymmetrical distribution of thunderstorms.

Tropical Storm Bill will move through an environment that will be only marginally favorable for intensification during the next 24 hours. Bill will move over the warmer water in the Gulf Stream where the Sea Surface Temperatures are near 27°C on Tuesday. However, the upper level trough east of the Great Lakes will continue to cause moderate vertical wind shear, which will inhibit intensification. Tropical Storm Bill could intensify a little more on Tuesday, but the wind shear is likely to increase by Tuesday night.

The upper level trough east of the Great Lakes will steer Tropical Storm Bill rapidly toward the northeast. On its anticipated track Tropical Storm Bill will pass southeast of Nova Scotia on Tuesday. Bill could approach southeast Newfoundland on Tuesday night.

Tropical Depression Two Forms East of Cape Hatteras

Tropical Depression Two formed east of Cape Hatteras on Monday morning. At 11:00 a.m. EDT on Monday the center of Tropical Depression Two was located at latitude 35.0°N and longitude 73.7°W which put it about 105 miles (165 km) east of Cape Hatteras, North Carolina. The tropical depression was moving toward the northeast at 21 m.p.h. (33 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 1006 mb.

More thunderstorms developed near the center of a low pressure system east of North Carolina on Monday morning and the National Hurricane Center designated the system as Tropical Depression Two. Bands of showers and thunderstorms also developed and the bands began to revolve around the center of the depression. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical depression. The removal of mass cause the surface pressure to decrease.

Tropical Depression Two will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over the warmer water of the Gulf Stream where the Sea Surface Temperatures are near 27°C. An upper level trough east of the Great Lakes will produce southwesterly winds which will blow toward the top of the depression. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Depression Two will likely strengthen to a tropical storm during the next 12 hours.

The upper level trough east of the Great Lakes will steer Tropical Depression Two rapidly toward the northeast. On its anticipated track Tropical Depression Two will move away from the U.S. It could pass southeast of Nova Scotia on Tuesday.

Low Pressure over Southwest Gulf of Mexico

A broad area of low pressure was over the southwestern Gulf of Mexico on Sunday afternoon. The system was designated as Invest 92L. At 2:00 p.m. EDT on Sunday the center of Invest 92L was located at latitude 20.0°N and longitude 96.0°W which put it about 100 miles (160 km) north-northeast of Veracruz, Mexico. The area of low pressure was nearly stationary. 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 1010 mb.

The broad area of low pressure exhibited a little more organization on Sunday afternoon. There was an apparent low level center located north-northeast of Veracruz, Mexico. However, there were few thunderstorms near the apparent center. Most of the thunderstorms were occurring far to the east and north of the apparent center. Some of the stronger winds were occurring in the thunderstorms far to the east and north of that center.

Invest 92L is likely to remain over the southwestern Gulf of Mexico during the next several days. The broad area of low pressure will be in an area somewhat favorable for the development of a tropical depression. Invest 92L will be over an area where the Sea Surface Temperatures are near 29°C. It will be under the northern part of an upper level ridge centered south of Mexico. The ridge will produce westerly winds which will blow across the top of the broad low pressure system. The westerly winds will cause moderate vertical wind shear, which will inhibit the formation of a tropical depression. The upper level ridge could move a little farther north in two or three days, which would cause the westerly winds to weaken. If that happens, then the conditions could become more favorable for the formation of a tropical depression. The National Hurricane Center is indicating that the probability is 50% that a tropical depression forms during the next five days.

Tropical Storm Carlos Forms Southwest of Baja California

Tropical Storm Carlos formed southwest of Baja California on Saturday night. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Carlos was located at latitude 11.9°N and longitude 124.5°W which put it about 1225 miles (1970 km) southwest of the southern tip of Baja California. Carlos was moving toward the west at 7 m.p.h. (11 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.

The circulation around a low pressure system southwest of Baja California exhibited more organization on satellite imagery on Saturday night and the National Hurricane Center designated the system as Tropical Storm Carlos. More thunderstorms were developing near the center of Carlos. Storms near the center of circulation began to generate upper level divergence that pumped mass away from the tropical storm. However, the distribution of thunderstorms was asymmetrical. The strongest thunderstorms were occurring in bands in the southern half of Tropical Storm Carlos. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 25 miles (40 km) on the northern side of Carlos. The winds were blowing at less than tropical storm force in the southern half of the circulation.

Tropical Storm Carlos will move through an environment that is somewhat favorable for intensification during the next 24 hours. Carlos will move over an area where the Sea Surface Temperatures are near 28°C. It will move under the southeastern part of an upper level ridge over the Eastern North Pacific Ocean. The ridge will produce northeasterly winds that will blow toward the top of Tropical Storm Carlos. Those winds will cause vertical wind shear and they already contributed to the asymmetrical distribution of thunderstorms. The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification. Tropical Storm Carlos will likely strengthen on Sunday.

Tropical Storm Carlos will move south of a subtropical high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Carlos toward the west during the next 24 hours. The steering currents could weaken during the early part of next week and Tropical Storm Carlos could meander slowly well to the southwest of Baja California.

Tropical Storm Koguma Nears Vietnam

The center of Tropical Storm Koguma moved closer to northern Vietnam on Saturday. At 11:00 a.m. EDT on Saturday the center of Tropical Storm Koguma was located at latitude 20.2°N and longitude 106.9°E which put it about 115 miles (185 km) southeast of Hanoi, Vietnam. Koguma was moving toward the northwest at 20 m.p.h. (32 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 997 mb.

The circulation around former Tropical Depression 05W strengthened slightly on Saturday and the system was upgraded to Tropical Storm Koguma. Even though the circulation around the former tropical depression was a little stronger, the distribution of thunderstorms around Tropical Storm Koguma was still asymmetrical. The strongest thunderstorms were occurring in bands southwest of the center of Koguma. Bands in the other parts of the tropical storm consisted primarily of showers and lower clouds. An upper level ridge centered over southern China was producing moderate northeasterly winds that were blowing toward the top of the depression. Those winds were causing moderate vertical wind shear and they were also causing the asymmetrical distribution of thunderstorms.

Tropical Storm Koguma will move into an environment only marginally favorable for intensification during the next few hours. Koguma will move over an area where the Sea Surface Temperatures are near 30°C. However, the upper level ridge over southern China will continue to produce moderate vertical wind shear. The moderate wind shear will keep Tropical Storm Koguma from strengthening significantly before it reaches Vietnam. The circulation around Koguma will weaken after the center moves over Vietnam.

Tropical Storm Koguma will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer Koguma toward the northwest. On its anticipated track the center of Tropical Storm Koguma will make landfall on the coast of northern Vietnam south of Haiphong in a few hours. Koguma will bring gusty winds to parts of northern Vietnam. Since the heaviest rain is falling southwest of the center of Tropical Storm Koguma, heavy rain is already falling over parts of northern Vietnam, northern Laos and extreme northeastern Thailand. The heavy rain could cause flash floods in some locations.

Tropical Depression Forms South of Hainan Island

A tropical depression formed just to the south of Hainan Island on Friday night. At 11:00 p.m. EDT on Friday the center of Tropical Depression 05W was located at latitude 18.3°N and longitude 109.5°E which put it about 35 miles (55 km) south of Sanya, China. The depression was moving toward the west at 16 m.p.h. (26 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 1000 mb.

Thunderstorms developed closer to the center of a low pressure system south of Hainan Island on Friday night and both the Japan Meteorological Agency and the Joint Typhoon Warning Center designated the system as a tropical depression. The distribution of thunderstorms around Tropical Depression 05W was asymmetrical. The strongest thunderstorms were occurring in bands southwest of the center of the tropical depression. Bands in the other parts of the circulation consisted primarily of showers and lower clouds. An upper level ridge centered over southern China was producing moderate northeasterly winds that were blowing toward the top of the depression. Those winds were causing moderate vertical wind shear and they were also causing the asymmetrical distribution of thunderstorms.

The center of Tropical Depression 05W will move near Hainan Island during the next few hours. The northern half of the circulation around the tropical depression will be over Hainan Island, which will inhibit intensification. Tropical Depression 05W will move into an environment favorable for intensification when it moves west of Hainan Island. The tropical depression will move over an area where the Sea Surface Temperatures are near 30°C. The upper level ridge over southern China will continue to produce moderate vertical wind shear. Even with the moderate wind shear, Tropical Depression 05W is likely to intensify to a tropical storm during the next 24 hours.

Tropical Depression 05W will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 36 hours. The high pressure system will steer the tropical depression toward the west-northwest. On its anticipated track the center of Tropical Depression 05W will pass near the southern part of Hainan Island. Since the strongest thunderstorms are in the southwestern part of the circulation, the tropical depression will cause mainly gustier winds over Hainan Island. Tropical Depression 05W could approach northern Vietnam in 24 hours. It could bring gusty winds and locally heavy rain to parts of northern Vietnam. Heavy rain could cause flash floods in some locations.

Tropical Storm Choi-wan Moves Toward Taiwan

Tropical Storm Choi-wan moved toward Taiwan on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Choi-wan was located at latitude 20.0°N and longitude 118.9°E which put it about 185 miles (300 km) south-southwest of Taiwan. Choi-wan was moving toward the north-northeast 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 1002 mb.

Tropical Storm Choi-wan turned toward the north-northeast on Thursday which put it on a track towards southern Taiwan. The distribution of thunderstorms around Choi-wan was asymmetrical. The strongest thunderstorms were occurring in bands in the southwestern quadrant of Tropical Storm Choi-wan. Bands in the other quadrants of Choi-wan consisted primarily of showers and lower clouds. The distribution of wind speeds around Tropical Storm Choi-wan was also asymmetrical. Winds to tropical storm force extended out 125 miles (200 km) on the western side of Choi-wan. Winds to tropical storm force only extended out 65 miles (105 km) on the eastern side of the circulation.

Tropical Storm Choi-wan will move through an area that is mostly unfavorable for intensification during the next 36 hours. The center of Choi-wan will move over an area where the Sea Surface Temperatures are near 30°C. However, an upper level ridge centered over southern China will produce moderate northeasterly winds that will blow toward the top of the tropical storm. Those winds will cause moderate vertical wind shear and they are already responsible for the asymmetrical distribution of thunderstorms. The moderate vertical wind shear will likely prevent intensification of Tropical Storm Choi-wan.

Tropical Storm Choi-wan will move around the northwestern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north-northeast during the next 24 hours. On its anticipated track the center of Tropical Storm Choi-wan will reach southern Taiwan in 12 hours. Choi-wan could drop locally heavy rain over parts of southern Taiwan. Flash floods could occur in some locations. Tropical Storm Choi-wan could approach the southern Ryuku Islands in 24 hours. Choi-wan could bring a period of gusty winds to southern Taiwan and the southern Ryukyu Islands.

Tropical Storm Choi-wan Drops Rain on Luzon

Tropical Storm Choi-wan dropped rain on parts of Luzon around Manila on Wednesday. At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Choi-wan was located at latitude 15.5°N and longitude 119.6°E which put it about 85 miles (135 km) west-northwest of Manila, Philippines. Choi-wan was moving toward the northwest at 16 m.p.h. (26 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.

The center of Tropical Storm Choi-wan passed just south of Manila before the tropical storm moved west of Luzon. Bands near the center of Choi-wan dropped rain on parts of Luzon near Manila. Other bands in the southern half of Tropical Storm Choi-wan dropped rain on Mindoro. Choi-wan was still producing a few winds that were blowing at tropical storm force, but Manila did not report any winds that were that strong.

Tropical Storm Choi-wan exhibited an organized circulation on Wednesday afternoon. The inner end of a rainband wrapped around the western, southern and eastern sides of the center of Choi-wan. Other bands of thunderstorms were in the southern half of the tropical storm. Bands in the northern half of Tropical Storm Choi-wan consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 35 miles (55 km) from the center of Choi-wan.

Tropical Storm Choi-wan will move through an area that is marginally favorable for intensification during the next 24 hours. The center of Choi-wan will move over the South China Sea where the Sea Surface Temperatures are near 30°C. However, an upper level ridge centered over southern China will cause moderate vertical wind shear. The wind shear will limit the potential for intensification, but Tropical Storm Choi-wan could get a little stronger during the next 24 hours.

Tropical Storm Choi-wan will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north during the next 24 hours. On its anticipated track the center of Tropical Storm Choi-wan will move northwest of Luzon during the next 24 hours. Choi-wan will turn toward the northeast on Friday after it moves around the western end of the high pressure system. Tropical Storm Choi-wan could approach the southern end of Taiwan in 36 hours.

Tropical Storm Choi-wan Brings Rain to Philippines

Tropical Storm Choi-wan brought rain to the central Philippines on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Choi-wan was located at latitude 13.1°N and longitude 121.9°E which put it about 155 miles (250 km) southeast of Manila, Philippines. Choi-wan was moving toward the west-northwest at 17 m.p.h. (28 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.

The center of Tropical Storm Choi-wan made an initial landfall on the east coast of Samar and then it moved west-northwest across the central Philippines. Choi-wan moved across the Sibuyan Sea and it was centered southeast of Manila on Tuesday night. The circulation around Tropical Storm Choi-wan weakened when the center passed over Samar, but it was still producing a small area of tropical storm force winds. Winds to tropical storm force extended out 35 miles (55 km) from the center of Choi-wan.

Tropical Storm Choi-wan dropped locally heavy rain over parts of Samar, Masbate, Panay and Mindoro on Tuesday. An upper level ridge centered over southern China was producing northeasterly winds which were blowing toward the top of Choi-wan. Those winds were producing moderate vertical wind shear and they causing the heavier rain to fall in bands in the southern half of Tropical Storm Choi-wan. Bands in the northern half of the tropical storm consisted primarily of showers and lower clouds.

Tropical Storm Choi-wan will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north-northwest during the next several days. On its anticipated track the center of Tropical Storm Choi-wan could pass just south of Manila in 12 hours. Choi-wan could drop locally heavy rain on Mindoro and western Luzon. Heavy rain could cause flash floods in some locations.

Tropical Storm Choi-wan will move through an environment that is mostly unfavorable for intensification. Choi-wan will move over water where the Sea Surface Temperatures are near 30°C. However, the upper level ridge center over southern China will continue to cause moderate vertical wind shear. The wind shear will limit the potential for intensification. The eastern side of the circulation around Tropical Storm Choi-wan will be over Luzon during the next 24 hours, which will also be unfavorable for intensification.

Tropical Storm Blanca Weakens South of Baja California

Tropical Storm Blanca weakened south of Baja California on Tuesday afternoon. At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Blanca was located at latitude 14.7°N and longitude 110.9°W which put it about 570 miles (915 km) south of the southern tip of Baja California. Blanca was moving toward the west-northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1001 mb.

After reaching its maximum intensity on Monday night when the sustained wind speed was 60 m.p.h. (95 km/h), Tropical Storm Blanca weakened on Tuesday afternoon. An upper level trough west of Baja California produced moderate southwesterly winds that blew toward the top of Blanca’s circulation. Those winds caused moderate vertical wind shear and the shear caused Tropical Storm Blanca to weaken. The vertical wind shear also caused an asymmetrical distribution of thunderstorms around Blanca. The strongest thunderstorms were occurring in bands on the eastern side of Tropical Storm Blanca. Bands in the western half of the tropical storm consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 45 miles (75 km) from the center of Blanca.

Tropical Storm Blanca will move through an environment unfavorable for intensification during the next several days. Blanca will move over water where the Sea Surface Temperatures are near 28°C. However the upper level trough west of Baja California will cause strong vertical wind shear and the wind shear will cause Blanca to weaken. Tropical Storm Blanca could weaken to a tropical depression in a day or two.

Tropical Storm Blanca will move around the southern part of a subtropical high pressure system over the Eastern North Pacific Ocean. The high will steer Blanca toward the west-northwest during the next two days. On its anticipated track Tropical Storm Blanca will move farther away from Baja California.