Monthly Archives: October 2021

Tropical Storm Lionrock Drops Heavy Rain on Hainan

Tropical Storm Lionrock dropped heavy rain on Hainan on Friday. At 11:00 a.m. EDT on Friday the center of Tropical Storm Lionrock was located at latitude 19.1°N and longitude 110.2°E which put it about 50 miles (80 km) south of Haikou, China. Lionrock was moving toward the north at 7 m.p.h. (11 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 991 mb.

Tropical Storm Lionrock brought gusty winds and heavy rain to Hainan on Friday. The center of Lionrock was over Hainan. Bands of showers and thunderstorms on the northern and western sides of Tropical Storm Lionrock were dropping heavy rain over much of Hainan. Bands on the southern and eastern sides of Lionrock consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. The circulation around Tropical Storm Lionrock was large. Winds to tropical storm force extended out 220 miles (350 km) from the center of circulation.

Tropical Storm Lionrock is likely to weaken during the next 12 hours while the center of circulation moves over Hainan. Lionrock will move into an environment favorable for intensification when the center moves over the Gulf of Tonkin. Lionrock will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western side of a small upper level ridge. The ridge will produce southerly winds that will blow toward the top of Lionrock’s circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Storm Lionrock is likely to intensify slowly after the center of circulation moves over the Gulf of Tonkin.

Tropical Storm Lionrock will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 12 hours. The subtropical high will steer Lionrock toward the northwest. On its anticipated track the center of Tropical Storm Lionrock will move across Hainan and it will emerge over the Gulf of Tonkin on Saturday. Lionrock will continue to bring gusty winds and locally heavy rain to Hainan during the next 12 hours. Heavy rain could cause flash floods in some locations. Tropical Storm Lionrock will move south of a second high pressure system that is centered over China during the weekend. The second high pressure system will steer Lionrock toward the west. Tropical Storm Lionrock could approach the coast of northern Vietnam in 36 hours.

Elsewhere over the Western North Pacific Ocean, a former tropical depression east of the Philippines strengthened to Tropical Storm Kompasu. At 11:00 a.m. EDT on Friday the center of Tropical Storm Kompasu was located at latitude 13.8°N and longitude 131.5°E which put it about 570 miles (920 km) east of Daet, Philippines. Kompasu was stationary. 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 998 mb.

Tropical Storm Lionrock Forms Southeast of Hainan

Tropical Storm Lionrock formed over the South China Sea southeast of Hainan on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Lionrock was located at latitude 17.5°N and longitude 111.0°E which put it about 95 miles (150 km) southeast of Lingshui, China. Lionrock was moving toward the north-northwest at 5 m.p.h. (8 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 994 mb.

The circulation around a low pressure system over the South China Sea strengthened on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Lionrock. There was a broad center of circulation in the middle of Tropical Storm Lionrock. Many of the thunderstorms were occurring in bands northeast and southwest of the broad center. Storms in the bands generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 150 miles (240 km) on the eastern side of Lionrock. Winds to tropical storm force extended out 75 miles (120 km) on the western side of the circulation.

Tropical Storm Lionrock will move through an environment somewhat favorable for intensification during the next 24 hours. Lionrock will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the eastern side of a small upper level ridge. The ridge will produce northeasterly winds that will blow toward the top of Lionrock’s circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Storm Lionrock is likely to intensify slowly during the next 24 hours because of the broad center of circulation.

Tropical Storm Lionrock will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 24 hours. The subtropical high will steer Lionrock toward the north-northwest. On its anticipated track the center of Tropical Storm Lionrock will reach Hainan in 24 hours. Lionrock will bring gusty winds and locally heavy rain to Hainan. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, a tropical depression formed east of the Philippines. At 5:00 p.m. EDT on Thursday the center of the tropical depression was located at latitude 13.3°N and longitude 129.7°E which put it about 400 miles (645 km) east of Legazpi, Philippines. The tropical depression was moving toward the east-northeast at 7 m.p.h. (11 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 1002 mb.

Tropical Cyclone Shaheen/Gulab Makes Landfall in Oman

Tropical Cyclone Shaheen/Gulab made landfall on the north coast of Oman on Sunday. At 5:00 p.m. EDT on Sunday the center of Tropical Cyclone Shaheen/Gulab was located at latitude 23.6°N and longitude 57.1°E which put it about 25 miles (40 km) southwest of Al Suwaiq, Oman. Shaheen/Gulab was moving toward the west-southwest at 8 m.p.h. (13 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 985 mb.

Tropical Cyclone Shaheen/Gulab made landfall on the north coast of Oman near Al Suwaiq on Sunday. Shaheen-Gulab was the equivalent of a strong tropical storm at the time of landfall. It was producing gusty winds and dropping heavy rain on parts of the northern coast of Oman. There were already reports of flash flooding causing casualties and damage in northern Oman. Winds to tropical storm force extended out about 80 miles (130 km) from the center of circulation. The was a ring of thunderstorms around the center and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of the tropical cyclone.

Tropical Cyclone Shaheen/Gulab will move south of a high pressure system over Southwest Asia. The high will steer Shaheen/Gulab toward the west-southwest during the next 36 hours. Tropical Cyclone Shaheen/Gulab will weaken steadily as it moves over mountains in northern Oman. Shaheen/Gulab will continue to drop locally heavy rain over the normally dry region during the next day or so and more flash floods are likely to occur.

It is very rare for a tropical cyclone to thread the needle and move so far to the west over the Gulf of Oman. The small size of Tropical Cyclone Shaheen/Gulab allowed much of its circulation to remain over the warm water in the Gulf of Oman. Drier air over Iran and the Arabian Peninsula was confined to the periphery of the circulation. The inner core of Shaheen/Gulab remained intact. Tropical Cyclone Shaheen was even more unusual because it started as Tropical Cyclone Gulab over the Bay of Bengal.

Tropical Cyclone Shaheen/Gulab Moves West over Gulf of Oman

Tropical Cyclone Shaheen/Gulab moved west over the Gulf of Oman on Saturday night. At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Shaheen/Gulab was located at latitude 24.3°N and longitude 59.0°E which put it about 70 miles (110 km) north-northeast of Muscat, Oman. Shaheen/Gulab was moving toward the west at 7 m.p.h. (11 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 979 mb.

Tropical Cyclone Shaheen/Gulab was over the Gulf of Oman on Saturday night. Winds blowing around the southwestern part of Shaheen/Gulab appeared to be pulling drier air over Oman into the southern and eastern part of the tropical cyclone. A small eye was present at the center of circulation. The was surrounded by a ring of thunderstorms, but there was a break in the southeastern part of the ring of storms. The strongest thunderstorms were occurring in a band on the western side of Tropical Cyclone Shaheen/Gulab. Bands in the southern and eastern parts of the circulation consisted primarily of showers and lower clouds. The circulation around Shaheen/Gulab was small. Winds to hurricane/typhoon force extended out 15 miles (25 km) from the center of circulation. Winds to tropical storm force extended out 80 miles (130 km) from the center.

Tropical Cyclone Shaheen/Gulab will move through an environment somewhat favorable for intensification during the next 12 hours. Shaheen/Gulab will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the middle of an upper level ridge over Southwest Asia. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear. However, dry air from Oman could continue to limit the development of thunderstorms in the southern and eastern parts of Shaheen/Gulab. Tropical Cyclone Shaheen/Gulab could strengthen during the next 12 hours. If more drier air reaches the core of Shaheen/Gulab, the remainder of the eyewall could weaken. That would reduce the maximum sustained wind speed.

Tropical Cyclone Shaheen/Gulab will move around the southern side of a high pressure system over Southwest Asia. The high will steer Shaheen/Gulab toward the west during the next 24 hours. On its anticipated track Tropical Cyclone Gulab could approach the coast of Oman near Sohar in 18 hours. Shaheen/Gulab will bring gusty winds and locally heavy rain to the part of Oman around Sohar. Heavy rain could cause flash floods. Tropical Cyclone Shaheen/Gulab will weaken quickly when it moves inland.

Hurricane Sam Passes East of Bermuda

Hurricane Sam passed east of Bermuda on Saturday morning. At 11:00 a.m. EDT on Saturday the center of Hurricane Sam was located at latitude 33.9°N and longitude 59.3°W which put it about 335 miles (540 km) east-northeast of Bermuda. Sam was moving toward the northeast at 17 m.p.h. (28 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 945 mb.

Hurricane Sam was still a powerful hurricane when it passed east of Bermuda on Saturday morning. Sam was rated at Category 4 on the Saffir-Simpson Scale. A circular eye with a diameter of 30 miles (50 km) was present at the center of Hurricane Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving round the core of Sam’s circulation. Storms near the core generated strong upper level divergence that pumped mass away to the north of the hurricane.

The size of the circulation around Hurricane Sam continued to increase in size as it moved farther to the north. Winds to hurricane force extended out 65 miles (10 km) from the center of Sam. Winds to tropical storm force extended out 240 miles (390 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 25.1. The Hurricane Size Index (HSI) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 45.7.

Hurricane Sam will move through an environment capable of maintaining a major hurricane during the next 12 hours. Sam 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 during the next 12 hours. An upper level trough east of the U.S. will produce southwesterly winds that will start to affect Hurricane Sam on Sunday. Those winds will blow toward the top of Sam’s circulation and they will cause more vertical wind shear. Hurricane Sam will also move over cooler water on Sunday. The wind shear and cooler water will cause Hurricane Sam to weaken as it begins a transition to a strong extratropical cyclone.

The upper level trough east of the U.S. will steer Hurricane Sam toward the northeast later during the next several days. On its anticipated track Hurricane Sam will pass southeast of Newfoundland on Monday. Sam could be a powerful extratropical cyclone southeast of Greenland by early next week.

Elsewhere over the Atlantic Ocean, Tropical Storm Victor weakened west of the Cabo Verde Islands. At 11:00 a.m. EDT on Saturday the center of Tropical Storm Victor was located at latitude 13.1°N and longitude 37.2°W which put it about 905 miles (1455 km) west of the Cabo Verde Islands. Victor 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 1005 mb.

Tropical Cyclone Shaheen/Gulab Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Shaheen/Gulab strengthened to the equivalent of a hurricane/typhoon over the Arabian Sea on Friday night. At 11:00 p.m. EDT on Friday the center of Tropical Cyclone Shaheen/Gulab was located at latitude 24.0°N and longitude 62.1°E which put it about 240 miles (390 km) east of Muscat, Oman. Shaheen/Gulab was moving toward the west-northwest at 8 m.p.h. (13 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 979 mb.

The India Meteorological Department renamed Tropical Cyclone Gulab as Tropical Cyclone Shaheen when it re-intensified over the Arabian Sea. Shaheen/Gulab intensified to the equivalent of a hurricane/typhoon east of Oman on Friday night. An eye formed at the center of Tropical Cyclone Shaheen/Gulab. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Outside the core of Shaheen/Gulab the strongest thunderstorms were occurring in bands in the southern half of the tropical cyclone. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Winds to hurricane/typhoon force extended out 20 miles (30 km) from the center of circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center.

Tropical Cyclone Shaheen/Gulab will move through an environment favorable for intensification during the next 12 hours. Shaheen/Gulab will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the middle of an upper level ridge over Southwest Asia and the northern Arabian Sea. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear. Tropical Cyclone Shaheen/Gulab could intensify during the next 12 hours. Dry air from Southwest Asia could limit the development of thunderstorms in the northern half of Shaheen/Gulab. If the drier air reaches the core of Tropical Cyclone Shaheen/Gulab, it could weaken during the weekend.

Tropical Cyclone Shaheen/Gulab will move around the southern side of a high pressure system over Southwest Asia. The high will steer Shaheen/Gulab toward the west during the next 36 hours. On its anticipated track Tropical Cyclone Gulab could approach the coast of Oman west of Muscat in 36 hours.

Bermuda Issues Tropical Storm Warning Because of Hurricane Sam

Bermuda issued a Tropical Storm Warning because of the potential effects of Hurricane Sam. At 5:00 p.m. EDT on Thursday the center of Hurricane Sam was located at latitude 23.6°N and longitude 60.9°W which put it about 645 miles (1040 km) south-southeast of Bermuda. Sam was moving toward the northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 170 m.p.h. (280 km/h). The minimum surface pressure was 938 mb.

A Tropical Storm Warning was in effect for Bermuda.

Hurricane Sam continued to be a powerful hurricane on Thursday. Sam was rated at Category 4 on the Saffir-Simpson Scale. A circular eye with a diameter of 28 miles (44 km) was present at the center of Hurricane Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving round the core of Sam’s circulation. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Sam was increasing in size as it moved farther to the north. Winds to hurricane force extended out 60 miles (95 km) from the center of Sam. Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 29.8. The Hurricane Size Index (HSI) was 17.5 and the Hurricane Wind Intensity Size Index (HWISI) was 47.3.

Hurricane Sam will move through an environment capable of maintaining a major hurricane during the next 36 hours. Sam will move over water where the Sea Surface Temperatures are near 28˚C. It will move through a region where the upper level winds are weak during the next 24 hours. An upper level trough east of the U.S. will produce southwesterly winds that will start to affect Hurricane Sam later on Friday. Those winds will blow toward the top of Sam’s circulation and they will cause more vertical wind shear. The wind shear will cause Hurricane Sam to start to weaken.

Hurricane Sam will move around the western end of a high pressure system over the Atlantic Ocean during the next 24 hours. The high will steer Sam toward the north during that time period. The upper level trough east of the U.S. will start to steer Hurricane Sam toward the northeast later on Friday. On its anticipated track Hurricane Sam will pass east of Bermuda on Friday night. The western fringes of Sam could bring gusty winds and locally heavy rain to Bermuda, which is why the Tropical Storm Warning was issued.

Elsewhere over the Atlantic Ocean, Tropical Storm Victor strengthened a little southwest of the Cabo Verde Islands. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Victor was located at latitude 9.9°N and longitude 30.0°W which put it about 585 miles (940 km) southwest of the Cabo Verde Islands. Victor was moving toward the west-northwest at 14 m.p.h. (22 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.