Monthly Archives: September 2021

Tropical Depression 16 Forms East of Northern Leeward Islands

Tropical Depression Sixteen formed east of the Northern Leeward Islands on Saturday night. At 11:00 p.m. EDT on Saturday the center of Tropical Depression Sixteen was located at latitude 16.4°N and longitude 53.1°W which put it about 670 miles (1080 km) east of the Northern Leeward Islands. The tropical depression was moving toward the west-northwest at 15 m.p.h. (24 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 1008 mb.

More thunderstorms developed near the center of a low pressure system east of the Northern Leeward Islands on Saturday night and the National Hurricane Center designated the system as Tropical Depression Sixteen. Thunderstorms were also developing in bands in the eastern and northern parts of the tropical depression. Bands in the southern and western parts of the circulation consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away to the north of the tropical depression.

Tropical Depression Sixteen will move through an environment somewhat favorable for intensification during the next 24 hours. The depression will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of an upper level ridge. The ridge will produce southerly winds that will blow toward the top of the tropical depression. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Depression Sixteen is likely to strengthen to a tropical storm on Sunday. The tropical depression will move closer to an upper level trough northeast of Puerto Rico on Monday. The upper level trough will produce strong southwesterly winds that will blow toward the top of the tropical depression. Those winds will cause moderate vertical wind shear, which is likely to weaken the tropical depression.

Tropical Depression Sixteen will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The high pressure system will steer the depression toward the west-northwest during the next 24 hours. On its anticipated track Tropical Depression Sixteen could be northeast of the Northern Leeward Islands by Monday morning.

Elsewhere over the Atlantic Ocean, Tropical Storm Odette made a transition to an extratropical cyclone south of Nova Scotia. At 5:00 p.m. EDT on Saturday the center of former Tropical Storm Odette was located at latitude 39.1°N and longitude 65.1°W which put it about 385 miles (625 km) south-southwest of Halifax, Nova Scotia. Odette was moving toward the east-northeast at 18 m.p.h. (29 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 1001 mb.

Tropical Storm Odette Forms South of New England

Tropical Storm Odette formed south of New England on Friday afternoon. At 5:00 p.m. EDT on Friday the center of Tropical Storm Odette was located at latitude 36.7°N and longitude 71.8°W which put it about 325 miles (525 km) south-southwest of Nantucket, Massachusetts. Odette was moving toward the northeast at 15 m.p.h. (24 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 1010 mb.

A new circulation center developed on the northern side of a larger low pressure system over the Atlantic Ocean south of New England on Friday afternoon and the National Hurricane Center designated the system as Tropical Storm Odette. The low level center of Odette was surrounded by lower clouds and showers. Thunderstorms were occurring in bands on the northern and eastern periphery of Tropical Storm Odette. Bands in the other parts of Odette’s circulation consisted primarily of showers and lower clouds. An upper level trough over the eastern U.S. was producing southwesterly winds that were blowing across the top of Tropical Storm Odette. Those winds were causing moderate vertical wind shear and the wind shear was contributing to the asymmetrical distribution of thunderstorms. Winds to tropical storm force extended out 115 miles (185 km) on the eastern side of Odette. The winds on the western side of the circulation were blowing at less than tropical storm force.

Tropical Storm Odette will move through an environment that is somewhat favorable for intensification during the next 36 hours. Odette will move over water in the Gulf Stream where the Sea Surface Temperatures are near 28˚C. The upper level trough over the eastern U.S. will continue to cause vertical wind shear, but the shear could decrease on Saturday. Tropical Storm Odette could strengthen during the next 24 hours. Odette will move over cooler water later in the weekend when it moves north of the Gulf Stream. Tropical Storm Odette will make a transition to an extratropical cyclone when it moves over cooler water. Odette could strengthen during the transition to an extratropical cyclone.

The upper level trough over the eastern U.S. will steer Tropical Storm Odette toward the northeast during the next 48 hours. On its anticipated track Tropical Storm Odette will pass southeast of Cape Cod. Odette could approach southeastern Newfoundland by late in the weekend.

Tropical Storm Chanthu Brings Gusty Winds and Rain to Japan

Tropical Storm Chanthu brought gusty winds and rain to parts of Japan on Friday. At 6:00 a.m. EDT on Friday the center of Tropical Storm Chanthu was located at latitude 33.7°N and longitude 130.6°E which put it about 10 miles (15 km) east of Fukuoka, Japan. Chanthu was moving toward the east-northeast at 17 m.p.h. (28 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 990 mb.

Tropical Storm Chanthu brought gusty winds to northern Kyushu and western Honshu on Friday. Winds to tropical storm force extended out 115 miles (185 km) from the center of Chanthu. The strongest winds were occurring in the parts of Chanthu’s circulation that were over water and in the mountains of western Japan. The heaviest rain was falling on the eastern side of Tropical Storm Chanthu.

Tropical Storm Chanthu will be steered quickly toward the east-northeast by the westerly winds in the middle latitudes. Tropical Storm Chanthu will move across Honshu during the next two days. The center of Tropical Storm Chanthu could be near Kyoto in 24 hours and near Tokyo in 36 hours. The upper level westerly winds will cause moderate vertical wind shear. The wind shear and movement across land will cause Chanthu to weaken gradually during the next 48 hours.

Tropical Storm Chanthu Spins between Japan and China

Tropical Storm Chanthu spun between Japan and China on Wednesday. At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Chanthu was located at latitude 30.5°N and longitude 125.2°E which put it about 360 miles (585 km) west-southwest of Kagoshima, Japan. Chanthu was moving toward the northwest at 4 m.p.h. (6 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 991 mb.

Tropical Storm Chanthu remained nearly stationary on Wednesday as it spun over the East China Sea between Japan and China. The atmospheric environment around Chanthu became more favorable for intensification when an upper level ridge moved over the tropical storm. Chanthu strengthened when the upper level ridge enhanced the upper level divergence that pumped more mass away from the tropical storm. The enhanced upper level divergence also contributed to the formation of more thunderstorms in the bands revolving around the center of Tropical Storm Chanthu. A rainband wrapped most of the way around the center of Chanthu and a new eye appeared to be forming at the center of the tropical storm. Winds to tropical storm force extended out 190 miles (305 km) on the northern side of Chanthu. Winds to tropical storm force extended out 90 miles (145 km) in the southern half of the circulation.

Tropical Storm Chanthu will move through an environment somewhat favorable for intensification during the next 24 hours. Chanthu will move over water where the Sea Surface Temperature is near 27˚C. Chanthu could mix cooler water to the surface while it remains nearly stationary, which could inhibit intensification. The upper level ridge will continue to enhance divergence, which will be favorable for intensification. Tropical Storm Chanthu is likely to intensify during the next 24 hours and it could strengthen back to a typhoon.

The steering winds are weak in the middle of the upper level ridge and Tropical Storm Chanthu may not move much during the next 12 to 18 hours. An upper level trough over eastern Asia will move eastward on Thursday. The upper level trough will start to steer Chanthu toward the west in 12 to 18 hours. On its anticipated track Tropical Storm Chanthu could approach Kyushu in 30 hours. Chanthu could be a typhoon when it reaches Kyushu. It will bring strong, gusty winds and locally heavy rain. Heavy rain could cause flash floods in some locations.

Tropical Storm Nicholas Brings Wind and Rain to Houston

Tropical Storm Nicholas brought wind and rain to Houston on Tuesday morning. At 8:00 a.m. EDT on Tuesday the center of Tropical Storm Nicholas was located at latitude 29.5°N and longitude 95.5°W which put it about 15 miles (25 km) south-southwest of Houston, Texas. Nicholas was moving toward the north-northeast at 8 m.p.h. (13 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 999 mb.

A Tropical Storm Warning was in effect for the portion of the coast from San Luis Pass, Texas to Cameron, Louisiana. The Tropical Storm Warning included Galveston and Port Arthur.

Tropical Storm Nicholas brought gusty winds and locally heavy rain to the area around Houston on Tuesday morning. Houston Intercontinental Airport was reporting a sustained wind speed of 33 m.p.h. (54 km/h) and a wind gust of 51 m.p.h. (82 km/h). The airport was reporting moderate rain. Moderate to heavy rain was also falling over southeast Texas and the southern half of Louisiana. A band of showers and thunderstorms extended from near Port Arthur, Texas southward over the Gulf of Mexico. Other bands of showers and thunderstorms were over southern Louisiana and southwestern Mississippi. Winds to tropical storm force extended out 125 miles (200 km) on the eastern side of Nicholas’ circulation. Winds to tropical storm force extended out 60 miles on the western side of the circulation.

Tropical Storm Nicholas will move slowly toward the east-northeast during the next 36 hours. The circulation around Nicholas will weaken gradually. Tropical Storm Nicholas will continue to drop locally heavy rain over southeast Texas, southern Louisiana and southern Mississippi. Flash Flood Watches are in effect for those locations.

Nicholas Strengthens to a Hurricane near Texas Coast

Former Tropical Storm Nicholas strengthened to a hurricane near the Texas coast on Monday night. At 11:00 p.m. EDT on Monday the center of Hurricane Nicholas was located at latitude 28.4°N and longitude 95.8°W which put it about 45 miles (75 km) southwest of Freeport, Texas. Nicholas was moving toward the north-northeast at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were’ wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 988 mb.

A Hurricane Waring was in effect for the portion of the coast from Port O’Connor to Freeport, Texas. A Hurricane Watch was in effect for the portion of the coast from Freeport to San Luis Pass, Texas. Tropical Storm Warnings were in effect for the portions of the coast from Port Aransas to Port O’Connor, Texas and from Freeport to Sabine Pass, Texas. The Tropical Storm Warning included Galveston.

Former Tropical Storm Nicholas strengthened to a hurricane on Monday night. An upper level ridge over the Gulf of Mexico enhanced upper level divergence to the northeast of Nicholas. The enhanced upper level divergence pumped away more mass and the surface pressure at the center of Nicholas decreased to 988 mb on Monday evening. The decreased pressure increased the pressure difference and a larger pressure gradient force caused the wind speed to gradually increase to hurricane force.

The circulation around Hurricane Nicholas was still asymmetrical. Drier air was wrapping around the southern side of Nicholas’ circulation and the precipitation was falling in the north half of the hurricane. The strongest winds were occurring in the eastern half of Hurricane Nicholas. Winds to hurricane force extended out 25 miles (40 km) in the northeastern quadrant of Nicholas. Winds to tropical storm force extended out 115 miles (185 km) on the eastern side of Hurricane Nicholas. Winds to tropical storm force extended out 45 miles on the western side of the hurricane.

Hurricane Nicholas will move around the western end of a high pressure system that extends over the Gulf of Mexico. The high pressure system will steer Nicholas toward the north-northeast during the next 24 hours. On its anticipated track the center of Hurricane Nicholas could make landfall near Freeport, Texas in a few hours. Hurricane Nicholas will bring strong winds to the coast of Texas between Matagorda and Port Arthur. Scattered power outages are likely. Nicholas will drop heavy rain over parts of southeastern Texas and over Louisiana on Tuesday. Flash floods could occur in some locations. Southerly winds blowing on the east side of Hurricane Nicholas will push water toward the coast. Those winds could cause a storm surge of up to 7 feet (2 meters). The water level will rise along the coast of southwest Louisiana too.

Chanthu Weakens to a Tropical Storm East of Shanghai

Former Typhoon Chanthu weakened to a tropical storm east of Shanghai on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Chanthu was located at latitude 31.3°N and longitude 123.9°E which put it about 150 miles (240 km) east of Shanghai, China. Chanthu was moving toward the northeast at 4 m.p.h. (6 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 988 mb.

Former Typhoon Chanthu weakened to a tropical storm east of Shanghai. An upper level trough over eastern China was producing southwesterly winds that were blowing toward the top of Tropical Storm Chanthu. Those winds were causing moderate vertical wind shear. In addition, the circulation around Chanthu was pulling drier air from Asia into the tropical storm. The drier air was mixing with the rainbands. The eye and eyewall at the center of former Typhoon Chanthu weakened. Thunderstorms were occurring in bands in the northeastern periphery of Tropical Storm Chanthu. Bands in other parts of Chanthu consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 200 miles (300 km) from the center of Chanthu.

Tropical Storm Chanthu will be in an area where the steering winds are weak during the next 24 hours. Chanthu will not move very much during that time period. Since Tropical Storm Chanthu will not move very far, its circulation will mix cooler water to the surface. A combination of moderate vertical wind shear, drier air and cooler water will cause Tropical Storm Chanthu to weaken gradually. Southwesterly winds in the middle latitudes will start to steer Chanthu toward the northeast in a day or so.

Tropical Storm Nicholas Nears Texas Coast

Tropical Storm Nicholas neared the coast of Texas on Monday morning. At 11:00 a.m. EDT on Monday the center of Tropical Storm Nicholas was located at latitude 26.4°N and longitude 96.8°W which put it about 140 miles (225 km) south of Port O’Connor, Texas. Nicholas was moving toward the north at 12 m.p.h. (19km/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 1002 mb.

A Hurricane Watch was in effect for the portion of the coast from Port Aransas to San Luis Pass, Texas. A Tropical Storm Warning was in effect for the portion of the coast from the Mouth of the Rio Grande River to Sabine Pass, Texas. The Tropical Storm Warning included Corpus Christi and Galveston.

The center of Tropical Storm Nicholas reorganized several times on Monday. Each time a new center formed farther to the north-northeast. The new centers formed on the southern sides of clusters of stronger thunderstorms. The inner end of a rainband appeared to be wrapping around the northern side of the most recent center of circulation. Other bands of stronger thunderstorms were occurring north and east of the center of Nicholas. Bands to the south and west of the center consisted primarily of showers and lower clouds. The strongest winds were occurring in the eastern half of Tropical Storm Nicholas. Winds to tropical storm force extended out 115 miles (185 km) on the eastern side of Nicholas. The winds in the western half of the circulation were blowing at less than tropical storm force.

Tropical Storm Nicholas will move through an environment favorable for intensification during the next 12 hours. Nicholas will move over water where the Sea Surface Temperatures are near 30˚C. It will move between and upper level trough over northern Mexico and an upper level ridge over the Gulf of Mexico. The upper trough and ridge will produce southerly winds that will blow toward the top of Nicholas’ circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. The upper level low will move west and weaken during the next 12 hours. The upper level ridge will extend northwest over Tropical Storm Nicholas. When the ridge extends over Nicholas the upper level winds will weaken. When the upper level winds weaken, the vertical wind shear will decrease. Tropical Storm Nicholas will strengthen when that occurs. If a more well defined center develops and persists in the middle of Nicholas, the it could strengthen more quickly. There is a chance that Nicholas could intensify to a hurricane later on Monday.

Tropical Storm Nicholas will move around the western side of a high pressure system that extends over the Gulf of Mexico. The high will steer Nicholas toward the north during the next 12 hours. On its anticipated track Tropical Storm Nicholas will approach the central coast of Texas on Monday night. Nicholas will bring gusty winds and locally heavy rain to coastal areas of northeast Texas on Monday night. The strongest winds and the heaviest rain will occur before the center of Tropical Storm Nicholas makes landfall. The strongest winds will occur on the eastern side of Nicholas’ circulation. Scattered power outages could occur along the Upper Texas Coast and in southwestern Louisiana. Tropical Storm Nicholas could also cause a storm surge of up to 7 feet (2 meters) along portions of the coast. Nicholas will move toward the northeast on Tuesday. Locally heavy rain will fall over Louisiana. Flash floods could occur in some locations.

Tropical Storm Nicholas Prompts Hurricane Watch for Texas

A potential threat posed by Tropical Storm Nicholas prompted the issuance of a Hurricane Watch for a portion of the Texas coast on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Nicholas was located at latitude 22.5°N and longitude 95.5°W which put it about 260 miles (415 km) south-southeast of the Mouth of the Rio Grande River. Nicholas was moving toward the north at 2 m.p.h. (3 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.

A Hurricane Watch was in effect for the portion of the coast from Port Aransas to Freeport, Texas. A Tropical Storm Warning was in effect for the portion of the coast from Barra el Mezquital, Mexico to High Island Texas. The Tropical Storm Warning included Corpus Christi and Galveston. A Tropical Storm Watch was in effect for the portion of the coast from High Island to Sabine Pass, Texas.

The circulation around Tropical Storm Nicholas was poorly organized. There was a broad center of circulation in the middle of Nicholas. Several smaller cyclonic circulations were revolving around inside the broad center. Many of the thunderstorms were occurring in bands in the northern half of Tropical Storm Nicholas. Bands in the southern half of Nicholas consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 115 miles (185 km) in the northeastern quadrant of Tropical Storm Nicholas. The winds in the other parts of Nicholas’ circulation were blowing at less than tropical storm force.

Tropical Storm Nicholas will move through an environment favorable for intensification during the next 24 hours. Nicholas will move over water where the Sea Surface Temperatures are near 30˚C. It will move between and upper level low over northern Mexico and an upper level ridge over the northwestern Caribbean Sea. The upper low and ridge will produce southerly winds that will blow toward the top of Nicholas’ circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. The upper level low will move west and weaken on Monday. The upper level ridge will extend west over Tropical Storm Nicholas. When the ridge extends over Nicholas the upper level winds will weaken. When the upper level winds weaken, the vertical wind shear will decrease. Tropical Storm Nicholas will strengthen when that occurs. If a more well defined center develops in the middle of Nicholas, the it could strengthen more quickly. There is a chance that Nicholas could intensify to a hurricane later on Monday.

Tropical Storm Nicholas will move around the western side of a high pressure system that extends over the Gulf of Mexico. The high will steer Nicholas toward the north-northwest during the next 24 hours. On its anticipated track Tropical Storm Nicholas will approach the coast near the Mouth of the Rio Grande River on Monday. Nicholas will bring gusty winds and locally heavy rain to coastal areas of northern Mexico and east Texas on Monday. Tropical Storm Nicholas could also cause a storm surge of up to 7 feet (2 meters) along portions of the coast. It is possible that a new center of circulation could develop closer to the thunderstorms in the northern half of Tropical Storm Nicholas. If a new center develops farther to the north, that could increase the threat to northeastern Texas and western Louisiana.

Typhoon Chanthu Moves Away from Taiwan

Typhoon Chanthu moved away from Taiwan on Sunday. At 11:00 a.m. EDT on Sunday the center of Typhoon Chanthu was located at latitude 26.8°N and longitude 122.7°E which put it about 105 miles (165 km) northeast of Taipei, Taiwan. Chanthu was moving toward the north-northeast at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h). The minimum surface pressure was 965 mb.

Typhoon Chanthu moved away from Taiwan on Sunday and the weather conditions were improving there. The core of Chanthu passed east of Taiwan and so it remained intact. A small circular eye was present at the center of Typhoon Chanthu. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Multiple bands of showers and thunderstorms were revolving around the core of Chanthu. Storms near the core generated upper level divergence that pumped mass away to the north of the typhoon.

The overall circulation of Typhoon Chanthu was larger after it moved past Taiwan. Winds to typhoon force extended out 25 miles (40 km) from the center of Chanthu. Winds to tropical storm force extended out 190 miles (305 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Chanthu was 19.2. The Hurricane Size Index (HSI) was 10.7 and the Hurricane Wind Intensity Size Index (HWISI) was 29.9. Typhoon Chanthu was capable of causing regional serious damage.

Typhoon Chanthu will move through an environment that will be mostly unfavorable for intensification during the next 36 hours. Chanthu will move over water where the Sea Surface Temperature is near 29˚C. An upper level trough over eastern China will produce southwesterly winds that will blow toward the top of Chanthu’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will likely be strong enough to cause Typhoon Chanthu to weaken gradually.

Typhoon Chanthu will move around the western side of a subtropical high pressure system over the Western North Pacific Ocean. The high will steer Chanthu toward the north during the next 24 hours. On its anticipated track Typhoon Chantu will continue to move away from Taiwan. Chanthu could approach the coast of Chine south of Shanghai in 24 hours. Typhoon Chanthu will bring gusty winds and locally heavy rain to the parts of east coast of China on Monday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression Conson weakened near the coast of Vietnam. At 11:00 a.m. EDT on Sunday the center of Tropical Depression Conson was located at latitude 15.4°N and longitude 109.1°E which put it about 70 miles (110 km) southeast of Da Nang, Vietnam. Conson was stationary. 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 1003 mb.