Monthly Archives: July 2021

Tropical Storm Hilda Develops South of Baja California

Tropical Storm Hilda developed south of Baja California on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Hilda was located at latitude 13.2°N and longitude 114.6°W which put it about 735 miles (1185 km) south-southwest of the southern tip of Baja California. Hilda was moving toward the west-northwest at 15 m.p.h. (24 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 a low pressure system south of Baja California exhibited more organization on Friday and the National Hurricane Center designated the system as Tropical Storm Hilda. The circulation around Tropical Storm Hilda was asymmetrical. A band of thunderstorms was wrapping around the western side of the center of Hilda. Other bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 100 miles (160 km) to the east of the center of Tropical Storm Hilda. Winds in the western side of Hilda were blowing at less than tropical storm force.

Tropical Storm Hilda will move through an environment favorable for intensification during the next 36 hours. Hilda 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 and there will be little vertical wind shear. Tropical Storm Hilda will intensify on Saturday and it could intensify to a hurricane during the next 36 hours.

Tropical Storm Hilda will move south of a high pressure system over the Eastern North Pacific Ocean. The high will steer Hilda toward the west-northwest during the next several days. On its anticipated track Tropical Storm Hilda will move farther away from Baja California.

Elsewhere, Tropical Depression Nine-E developed west of Tropical Storm Hilda on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Depression Nine-E was located at latitude 12.5°N and longitude 126.2°W which put it about 1290 miles (2075 km) southwest of the southern tip of Baja California. The depression was moving toward the west at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1007 mb.

Tropical Storm Nepartak Strengthens East of Tokyo

Tropical Storm Nepartak strengthened east of Tokyo on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Nepartak was located at latitude 35.4°N and longitude 142.3°E which put it about 160 miles (260 km) east of Tokyo, Japan. Nepartak was moving toward the north-northwest at 5 m.p.h. (8 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 992 mb.

Tropical Storm Nepartak exhibited a structure a little more like a tropical cyclone on Monday night. Nepartak was embedded in the center of an upper level low. The center of Tropical Storm Nepartak was under the center of the upper level low and the circulation assumed a more circular shape. Bands of showers and thunderstorms were revolving around the center of Nepartak. Winds to tropical storm force extended out 160 miles (260 km) in the eastern side of the circulation. Winds to tropical storm force extended out 100 miles (160 km) in the western side of Nepartak.

Tropical Storm Nepartak will move through an environment capable of supporting a tropical storm during the next 18 hours. Nepartak will move over water where the Sea Surface Temperatures are near 26°C. Since Tropical Storm Nepartak is embedded at the center of an upper level low, the winds are blowing from the same direction at all levels in the troposphere. So, there will be little vertical wind shear. Tropical Storm Nepartak will likely maintain its intensity during the next 18 hours and it could strengthen a little more.

The upper level low and Tropical Storm Nepartak are forecast to drift toward the northwest during the next 24 hours. On its anticipated track the center of Nepartak could make landfall on the northern coast of Honshu near Sendai in about 18 hours. Tropical Storm Nepartak will bring gusty winds and locally heavy rain to parts of northern Honshu. Nepartak already generated waves along the coast of Honshu and some Olympic events at coastal sites were postponed.

Elsewhere, Tropical Storm In-Fa continued to drop heavy rain over parts of eastern China. At 11:00 p.m. EDT on Monday the center of Tropical Storm In-Fa was located at latitude 31.2°N and longitude 119.5°E which put it about 100 miles (160 km) west of Shanghai, China. In-Fa was moving toward the west-northwest at 4 m.p.h. (6 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 982 mb.

Tropical Storm In-Fa Makes Landfall near Shanghai

Tropical Storm In-Fa made landfall on the east coast of China near Shanghai on Sunday. At 5:00 p.m. EDT on Sunday the center of Tropical Storm In-Fa was located at latitude 30.6°N and longitude 121.4°E which put it about 50 miles (80 km) south of Shanghai, China. In-Fa was moving toward the northwest at 6 m.p.h. (10 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 987 mb.

Tropical Storm In-Fa weakened slowly as it approached the east coast of China. The circulation around In-Fa pulled drier air from Asia into the western side of the former typhoon. The drier air caused thunderstorms in the western half of Tropical Storm In-Fa to weaken. The strongest thunderstorms were occurring in bands on the eastern side of In-Fa. Bands in the western half of the tropical storm consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 165 miles (270 km) on the eastern side of In-Fa. The strongest winds were occurring over the waters of the East China Sea. Winds to tropical storm force extended out 80 miles on the western side of the circulation.

Tropical Storm In-Fa will move slowly toward the northwest, which will take it farther inland over eastern China. The circulation around In-Fa will weaken gradually as the tropical storm moves farther inland. Tropical Storm In-Fa will bring gusty winds and locally heavy rain to the region around Shanghai and Ningbo. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nepartak swirled southwest of Japan. At 5:00 p.m. EDT on Sunday the center of Tropical Storm Nepartak was located at latitude 33.4°N and longitude 149.7°E which put it about 630 miles (1015 km) east-southeast of Tokyo, Japan. Nepartak was moving toward the north at 13 m.p.h. (20 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 998 mb.

Typhoon In-Fa Brings Wind and Rain to Ryukyu Islands

Typhoon In-Fa brought gusty winds and locally heavy rain to the Ryukyu Islands on Friday. At 11:00 a.m. EDT on Friday the center of Typhoon In-Fa was located at latitude 25.1°N and longitude 124.9°E which put it about 30 miles (50 km) northwest of Hirara, Japan. In-Fa was moving toward the northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 969 mb.

The slow movement of Typhoon In-Fa during the past several days and its large size caused In-Fa to mix cooler water to the surface in a large area. The cooler water meant that In-Fa extracted less energy from the ocean and thunderstorms weakened in parts of the circulation around the typhoon. There was still a large circular eye with a diameter of of 65 miles (105 km) at the center of Typhoon In-Fa. The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in the broken ring of storms. Bands of showers and thunderstorms continued to revolve around the center of In-Fa. Storms near the center of circulation generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon In-Fa was large. Winds to typhoon force extended out 80 miles (130 km) from the center of In-Fa. Winds to tropical storm force extended out 270 miles (435 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon In-Fa was 11.5. The Hurricane Size Index (HSI) was 31.7 and the Hurricane Wind Intensity Size Index (HWISI) was 43.2.

Typhoon In-Fa will move through an environment somewhat favorable for intensification during the next 24 hours. Once the center of In-Fa moves away from the cooler water mixed to the surface, the typhoon 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 and there will be little vertical wind shear. The large size of Typhoon In-Fa will mean that intensification could be slow to occur. Typhoon In-Fa could strengthen during the next 24 hours.

Typhoon In-Fa will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high will steer In-Fa toward the northwest. On its anticipated track Typhoon In-Fa will move slowly away from the Ryukyu Islands. Since the circulation around In-Fa is so large, the typhoon will continue to produce gusty winds and locally heavy rain for another 24 hours. The center of Typhoon In-Fa could approach the east coast of China south of Ningbo in 48 hours.

Possible Development near Southeast U.S.

A low pressure system could develop near the coast of the Southeast U.S. during the next 48 hours. At 8:00 a.m. EDT on Friday the center of a developing low pressure system currently designated as Invest 90L was located at latitude 31.3°N and longitude 79.3°W which put it about 150 miles (240 km) east of Brunswick, Georgia. It was moving toward the east-southeast at 9 m.p.h. (15 km/h). 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 1017 mb.

Early morning visible satellite images appeared to show that a low pressure system was forming along a nearly stationary front off the coast of the southeast U.S. More thunderstorms were forming in the developing low pressure system and some rotation was evident in satellite loops. Thunderstorms appeared to be organizing into bands. The southern end of an upper level trough over the eastern U.S. was producing westerly that were blowing across the top of the developing low pressure system. Those winds were causing moderated vertical wind shear. The upper level winds were also inhibiting the development of thunderstorms on the western side of the developing low pressure system.

The low pressure system will move through an environment somewhat favorable for the formation of a tropical cyclone during the next 48 hours. It will move over water where the Sea Surface Temperatures are near 28°C. The upper level trough will move northeast of the low pressure system on Saturday and the upper level winds will weaken. An upper level low east of the Bahamas could enhance upper level divergence to the southeast of the developing low pressure system. The National Hurricane Center is indicating the probability is 30% that a tropical cyclone forms during the next 48 hours. A reconnaissance plane has been tentatively tasked to investigate the system on Saturday afternoon, if necessary.

Typhoon In-Fa Churns Southeast of Ishigaki

Typhoon In-Fa churned southeast of Ishigaki, Japan on Thursday. At 11:00 a.m. EDT on Thursday the center of Typhoon In-Fa was located at latitude 23.7°N and longitude 125.8°E which put it about 120 miles (195 km) southeast of Ishigaki, Japan. In-Fa was moving toward the northwest at 2 m.p.h. (3 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 957 mb.

Typhoon In-Fa went through an eyewall replacement cycle as it moved slowly toward the southwestern Ryukyu Islands on Thursday. The inner end of an rainband wrapped completely around the original eye and eyewall. Two concentric eyewalls existed simultaneously for a time on Wednesday. Low level convergence became concentrated in the newer, outer eyewall and the inner eyewall dissipated. The eyewall replacement cycle left a much larger eye with a diameter of 65 miles (105 km) at the center of Typhoon In-Fa. Bands of showers and thunderstorms were revolving around the new, larger eye. Storms near the eye generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon In-Fa was large. Winds to typhoon force extended out 70 miles (110 km) from the center of In-Fa. Winds to tropical storm force extended out 230 miles (370 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon In-Fa was 16.5. The Hurricane Size Index (HSI) was 27.4 and the Hurricane Wind Intensity Size Index (HWISI) was 43.9 .

Typhoon In-Fa will move through an environment favorable for intensification during the next 24 hours. In-Fa will move over water where the Sea Surface Temperatures are near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon In-Fa has moved little during the past 12 hours and it has mixed cooler water to the surface. Once In-Fa starts to move a little faster, the core of the typhoon will move back over warmer water. Typhoon In-Fa is likely to strengthen during the next 24 hours and it could intensify to the equivalent of a major hurricane.

Typhoon In-Fa will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high will steer In-Fa toward the northwest. On its anticipated track the center of Typhoon In-Fa will be near the southwestern Ryukyu Islands in 18 hours. In-Fa will be capable of causing widespread serious damage. It will also cause a significant storm surge. Typhoon In-Fa will drop heavy rain and flash floods are likely. The core of In-Fa could be northeast of Taiwan in 36 hours. In-Fa will also drop heavy rain on parts of northern Taiwan and flash floods are likely there as well.

Elsewhere, Tropical Depression Cempaka continued to meander over southern China. At 11:00 a.m. EDT on Thursday the center of Tropical Depression Cempaka was located at latitude 21.9°N and longitude 107.8°E which put it about 25 miles (40 km) north of Mong Cai, Vietnam. Cempaka was moving toward the northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1003 mb.

Typhoon In-Fa Moves Toward Southwestern Ryukyu Islands

Typhoon In-Fa moved toward the southwestern Ryukyu Islands on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Typhoon In-Fa was located at latitude 23.9°N and longitude 126.5°E which put it about 155 miles (250 km) east-southeast of Ishigaki, Japan. In-Fa was moving toward the west-southwest at 7 m.p.h. (11 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 951 mb.

Typhoon In-Fa moved closer to the southwestern Ryukyu Islands on Wednesday. In-Fa was a large, powerful typhoon. A circular eye with a diameter of 30 miles (50 km) was at the center of Typhoon In-Fa. The eye was nearly surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. There was a break in the eastern side of the ring around the eye. Bands of showers and thunderstorms were revolving around the core of Typhoon In-Fa. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon In-Fa was large. Winds to typhoon force extended out 80 miles (130 km) from the center of In-Fa. Winds to tropical storm force extended out 250 miles (400 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon In-Fa was 19.2. The Hurricane Size Index (HSI) was 25.1 and the Hurricane Wind Intensity Size Index (HWISI) was 44.3.

Typhoon In-Fa will move through an environment favorable for intensification during the next 24 hours. In-Fa 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 In-Fa is likely to strengthen to the equivalent of a major hurricane during the next 24 hours.

Typhoon In-Fa will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high will steer In-Fa toward the west. On its anticipated track the center of Typhoon In-Fa will be near the southwestern Ryukyu Islands in 36 hours. In-Fa will be capable of causing widespread major damage. It will also cause a significant storm surge. Typhoon In-Fa will drop heavy rain and flash floods are likely. The core of In-Fa could be northeast of Taiwan in 60 hours. In-Fa will also drop heavy rain on parts of Taiwan and flash floods are likely there as well.

Elsewhere, Tropical Depression Cempaka was moving over southern China. At 11:00 a.m. EDT on Wednesday the center of Tropical Depression Cempaka was located at latitude 22.5°N and longitude 110.3°E which put it about 5 miles (10 km) east of Yulin, China. Cempaka was moving toward the northwest at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1003 mb.

Typhoon Cempaka Makes Landfall in Southern China

Typhoon Cempaka made landfall in southern China on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Typhoon Cempaka was located at latitude 21.8°N and longitude 111.9°E which put it about 10 miles (15 km) south of Yangjiang, China. Cempaka was moving toward the northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 972 mb.

Typhoon Cempaka made landfall on the coast of southern China just to the south of Yangjiang in the province of Guangdong on Tuesday. Cempaka brought strong winds and locally heavy rain to the southwestern part of Guangdong. Winds to typhoon force extended out 25 miles (40 km) from the center of Cempaka at the time of landfall. Winds to tropical storm force extended out 100 miles (160 km) from the center of circulation.

Typhoon Cempaka will weaken rapidly as the center moves inland. However, since Cempaka will move slowly, it could drop heavy rain over the southwestern part of Guangdong province. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm In-Fa intensified to a typhoon south-southeast of Okinawa. At 11:00 a.m. EDT on Tuesday the center of Typhoon In-Fa was located at latitude 24.5°N and longitude 128.7°E which put it about 150 miles (245 km) south-southeast of Okinawa. In-Fa was moving toward the west at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 968 mb. Typhoon In-Fa is forecast to move toward the west during the next several days and to intensify to the equivalent of a major hurricane. The center of In-Fa will pass south of Okinawa during the next 24 hours. It could be over the southwestern Ryukyu Islands in 48 hours and near northern Taiwan in three days.

Cempaka Strengthens to a Typhoon Southwest of Hong Kong

Former Tropical Storm Cempaka strengthened to a typhoon southwest of Hong Kong on Monday. At 5:00 p.m. EDT on Monday the center of Typhoon Cempaka was located at latitude 21.3°N and longitude 112.4°E which put it about 130 miles (210 km) southwest of Hong Kong. Cempaka was moving toward the west-northwest at 3 m.p.h. (5 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 978 mb.

The small circulation around former Tropical Storm Cempaka strengthened quickly on Monday. A small circular eye formed at the center of Typhoon Cempaka. The eye was surrounded by a ring of strong thunderstorms. Bands of showers and thunderstorms were revolving around the core of Cempaka. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 20 miles (30 km) from the center of Cempaka. Winds to tropical storm force extended out 40 miles (65 km) from the center of circulation.

Typhoon Cempaka will move through an environment favorable for intensification during the next 12 hours. Cempaka will move over water where the Sea Surface Temperatures are near 30°C. It will remain under an upper level ridge over the South China Sea. The winds are weak in the ridge and there will be little vertical wind shear. Typhoon Cempaka could intensify during the next 12 hours.

Typhoon Cempaka will move south of a surface high pressure system over eastern China. The high pressure system will steer Cempaka slowly toward the west-northwest during the next 36 hours. On its anticipated track Tropical Storm Cempaka could approach the south coast of China near Yangjiang in about 12 hours. Cempaka will bring strong winds and heavy rain to the coast of Guangdong province. Since Cempaka will move very slowly some locations could receive extremely heavy rainfall and flash floods are likely in those places. Typhoon Cempaka could also produce of storm surge of up to 7 feet (2 meters) along parts of the coast where the wind blows the water toward the shore.

Elsewhere over the Western North Pacific Ocean, Tropical Storm In-Fa stalled southeast of Okinawa. At 5:00 p.m. EDT on Monday the center of Tropical Storm In-Fa was located at latitude 24.3°N and longitude 130.9°E which put it about 265 miles (425 km) southeast of Okinawa. In-Fa was moving toward the west-northwest 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 983 mb. Tropical Storm In-Fa is forecast to move toward the west during the next several days and to intensify to a typhoon. In-Fa could be south of Okinawa in 30 hours. It could be over the southwestern Ryukyu Islands in 72 hours and near northern Taiwan in less than four days.

Hurricane Felicia and Tropical Storm Guillermo Weaken

Both Hurricane Felicia and Tropical Storm Guillermo weakened on Monday morning. At 11:00 a.m. EDT on Monday the center of Hurricane Felicia was located at latitude 16.3°N and longitude 132.3°W which put it about 1515 miles (2435 km) east of Hilo, Hawaii. Felicia was moving toward the west at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 990 mb.

Hurricane Felicia weakened rapidly on Monday morning. Felicia moved over water where the Sea Surface Temperatures was near 26°C. The air over the cooler water was also drier. When the drier air entered the small circulation around Hurricane Felicia, thunderstorms in the eyewall and in the rainbands weakened. The eye at the center of Felicia filled with lower clouds. Many of the bands consisted primarily of showers and lower clouds. The strongest thunderstorms were occurring in a small area east of the center of circulation. Winds to hurricane force extended out 15 miles (25 km) from the center. Winds to tropical storm force extended out 45 miles (75 km) from the center of circulation.

Hurricane Felicia will continue to weaken during the next several days. Felicia will move over water where the Sea Surface Temperatures are near 26°C. It will continue to be an environment where the air is relatively dry, which will inhibit the formation of thunderstorms. An upper level trough near Hawaii will produce southwesterly winds that will blow across the top of Felicia. Those winds will cause moderate vertical wind shear and the wind shear will cause Felicia to weaken faster. Hurricane Felicia could weaken to a tropical depression by Tuesday night.

Hurricane Felicia will move south of a subtropical high pressure system over the Eastern North Pacific Ocean. The high will steer Felicia toward the west during the next several days. On its anticipated track the remnants of Hurricane Felicia could pass south of Hawaii at the end of the week.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Guillermo also weakened on Monday morning. At 11:00 a.m. EDT on Monday the center of Tropical Storm Guillermo was located at latitude 19.1°N and longitude 117.8°W which put it about 575 miles (925 km) west-southwest of the southern tip of Baja California. Guillermo was moving toward the west 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 1005 mb.