Category Archives: Tropical Cyclones

Information about tropical cyclones

Tropical Depression Two Strengthens to Tropical Storm Arlene

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Former Tropical Depression Two strengthened to Tropical Storm Arlene over the eastern Gulf of Mexico on Friday afternoon. At 2:00 p.m. EDT on Friday the center of Tropical Storm Arlene was located at latitude 26.7°N and longitude 86.2°W which put it about 265 miles (425 km) west of Ft. Meyers, Florida. Arlene was moving toward the south 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 1002 mb.

An Air Force Reserve Hurricane Hunter reconnaissance plane found sustained wind speeds to tropical storm force in the northeastern part of former Tropical Depression Two on Thursday afternoon and the National Hurricane Center upgraded the system to Tropical Storm Arlene. The distribution of thunderstorms in Tropical Storm Arlene was asymmetrical. Many of the thunderstorms were occurring in bands in the northeastern quadrant of Arlene’s circulation. Bands in the other parts of the tropical storm consisted primarily of showers and lower clouds. Storms near the center of Arlene generated upper level divergence that pumped mass away to the northeast of the tropical storm. Winds to tropical storm force extended out 65 miles (105 km) in the northeastern quadrant of Tropical Storm Arlene. The winds in the other parts of Arlene were blowing at less than tropical storm force.

Tropical Storm Arlene will move into an environment that will become unfavorable for intensification during the next 24 hours. Arlene will move over water where the Sea Surface Temperatures are near 27˚C. However, Tropical Storm Arlene will move under the southern part of an upper level trough over the eastern Gulf of Mexico. The upper level trough will produce westerly winds that will blow toward the top of Arlene’s circulation. Those winds will cause the vertical wind shear to increase. Drier air to the north and west of Tropical Storm Arlene will continue to inhibit the formation of thunderstorms in the western part of Arlene. The vertical wind shear and the drier air are likely to cause Tropical Storm Arlene to start to weaken during the next 24 hours.

Tropical Storm Arlene will be south of a large surface high pressure system over the eastern U.S. The high pressure system will move south on Friday and it will push Tropical Storm Arlene toward the south. On its anticipated track Tropical Storm Arlene will stay west of Florida. Arlene could move near the western end of Cuba by Saturday evening.

Tropical Depression Two Forms over Northeast Gulf of Mexico

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Tropical Depression Two formed over the northeast Gulf of Mexico on Thursday afternoon. At 5:00 p.m. EDT on Thursday the center of Tropical Depression Two was located at latitude 28.0°N and longitude 86.6°W which put it about 250 miles (400 km) west of St. Petersburg, Florida. The tropical depression was moving toward the west-northwest at 2 m.p.h. (3 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1007 mb.

Surface observations from buoys in the Gulf of Mexico and data acquired by a U.S. Air Force Hurricane Hunter reconnaissance plane indicated that a low pressure system over the northeast Gulf of Mexico had formed into a tropical depression on Thursday afternoon. Tropical Depression Two had a broad low level center of circulation. The distribution of thunderstorms in the tropical depression was asymmetrical. Many of the thunderstorms were occurring in bands in the eastern and northern part of Tropical Depression Two. Bands in the western and southern parts of the tropical depression consisted primarily of showers and lower clouds.

The surface center of Tropical Depression Two was slightly east of the axis of an upper level trough over the eastern Gulf of Mexico. The upper level trough was producing southwesterly winds that were blowing toward the top of the tropical depression. Those winds were causing vertical wind shear and the wind shear was contributing to the asymmetrical distribution of thunderstorms. In addition, drier air was north and west of Tropical Depression Two. The drier air was inhibiting the development of thunderstorms in the western part of the depression’s circulation.

Tropical Depression Two will be in an environment only marginally favorable for intensification during the next 24 hours. The tropical depression will be over water where the Sea Surface Temperatures are near 27˚C. However, the upper level trough over the eastern Gulf of Mexico will continue to cause vertical wind shear. The drier air will also continue to inhibit the formation of thunderstorms in the western part of the tropical depression. If the vertical wind shear does not get any stronger, then the tropical depression could strengthen to a tropical storm during the next 24 hours. On the other hand, if the wind shear increases, then the tropical depression could start to weaken.

Tropical Depression Two will be south of a large surface high pressure system over the eastern U.S. The steering currents will be weak during the next 12 hours and the tropical depression may not move much. The high pressure system will move south on Friday and it will start to push Tropical Depression Two toward the south. On its anticipated track Tropical Depression Two will stay southwest of Florida. It could move near the western end of Cuba by Saturday night.

Tropical Storm Mawar Brings Wind and Rain to Okinawa

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Tropical Storm Mawar brought wind and rain to Okinawa on Thursday. At 11:00 a.m. EDT on Thursday the center of Tropical Storm Mawar was located at latitude 26.1°N and longitude 127.5°E which put it about 65 miles (105 km) southwest of Okinawa. Mawar was moving toward the northeast at 13 m.p.h. (20 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 972 mb.

Former Typhoon Mawar weakened to a tropical storm as it moved closer to Okinawa on Thursday. Even though Mawar was a tropical storm, it still produced gusty winds and rain in Okinawa. A weather station in Naha measured a sustained wind speed of 41 m.p.h. (66 km/h). The distribution of thunderstorms was asymmetrical in Tropical Storm Mawar. Most of the thunderstorms were occurring in bands east and south of the center of Mawar. Bands in the northern and western parts of Tropical Storm Mawar consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 250 miles (400 km) from the center of Mawar’s circulation.

Tropical Storm Mawar will move through an environment that will be unfavorable for intensification during the next 48 hours. Mawar will move over water where the Sea Surface Temperatures are near 25˚C. It will move under the eastern part of an upper level trough that is west of Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Mawar’s circulation. Those winds will cause more vertical wind shear. Tropical Storm Mawar will also pull drier air from Asia into the western part of its circulation. More vertical wind shear and drier air will cause Tropical Storm Mawar to gradually weaken.

The upper level trough west of Japan will steer Tropical Storm Mawar toward the northeast during the next 48 hours. On its anticipated track the center of Mawar will pass near Okinawa during the next few hours. Weather conditions in Okinawa will start to improve when Tropical Storm Mawar moves away later today. Mawar will pass south of Honshu after it moves away from Okinawa. Tropical Storm Mawar could pass south of Tokyo in less than 48 hours.

Low Pressure System Develops over Gulf of Mexico

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A weak low pressure system developed over the eastern Gulf of Mexico on Wednesday. The system was designated as Invest 91L by the National Hurricane Center. At 2:00 p.m. EDT on Wednesday the center of Invest 91L was located at latitude 26.4°N and longitude 85.9°W which put it about 275 miles (445 km) west of Naples, Florida. The low pressure system 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 1009 mb.

A weak low pressure system developed over the eastern Gulf of Mexico on Wednesday and the system was designated as Invest 91L. The circulation around Invest 91L was not well organized. There was a broad counterclockwise rotation around the center of the low pressure system. At least one smaller center of rotation, that might have formed in a cluster of thunderstorms that dissipated on Tuesday night, was visible in the eastern side of the broader rotation. There were bands of showers and thunderstorms in the eastern and northern sides of the low pressure system. Bands in the western and southern parts of the system consisted primarily of lower clouds.

Invest 91L will be in an environment only marginally favorable for development of a tropical cyclone during the next 24 hours. The surface low pressure system will be over water where the Sea Surface Temperatures are near 27˚C. It will be under the eastern side of an upper level trough over the northeastern Gulf of Mexico. The upper level trough will produce southwesterly winds that will blow across the top of Invest 91L. Those winds will cause wind shear and the wind shear will inhibit the development of the surface low pressure system. There is also drier air over the northern Gulf of Mexico. The drier air will inhibit the formation of thunderstorms in the northern and western parts of Invest 91L. The National Hurricane Center is indicating that the probability is 20% that Invest 91L develops into a tropical cyclone during the next 48 hours. A reconnaissance plane is tentatively scheduled to investigate the system on Thursday afternoon, if necessary.

Invest 91L will continued to be under the eastern side of the upper level trough over the eastern Gulf of Mexico during the next 24 hours. The steering winds are weak under the upper level trough. So, Invest 91L could move with the upper level trough. The upper level trough is forecast to move slowly toward the east. Invest 91L could move slowly toward the southeast. If Invest 91L develops into a tropical cyclone with taller thunderstorms, then the winds in the middle troposphere could steer it more toward the north. Bands in the eastern side of the low pressure system are likely to bring locally heavy rain to parts of central and south Florida.

Typhoon Mawar Moves South-southeast of Miyakojima

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Typhoon Mawar move south-southeast of Miyakojima on Wednesday morning. At 11:00 a.m. EDT on Wednesday the center of Typhoon Mawar was located at latitude 23.0°N and longitude 125.6°E which put it about 120 miles (195 km) south-southeast of Miyakojima, Japan. Mawar was moving toward the north-northeast at 5 m.p.h. (8 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 981 mb.

Typhoon Mawar continued to weaken slowly as it moved closer to the southern Ryukyu Islands on Wednesday. The circulation around Mawar was pulling drier air from Asia into the western part of the typhoon. Bands in the western half of Typhoon Mawar consisted primarily of showers and lower clouds. Many of the thunderstorms in Mawar were occurring in bands in the eastern half of the typhoon. Storms in the eastern half of Mawar’s circulation generated upper level divergence that pumped mass away to the east of the typhoon. Winds to typhoon force extended out 60 miles (95 km) from the center of Mawar. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation.

Typhoon Mawar will move through an environment that will be less favorable for intensification during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 27˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. The drier air in the western half of Mawar’s circulation air will inhibit the formation of thunderstorms in that part of the typhoon. In addition, since Typhoon Mawar is moving slowly, winds in the lower levels are likely to mix cooler water to the surface of the Pacific Ocean. The effects of the drier air and mixing of cooler water to the surface of the ocean are likely to cause Typhoon Mawar to weaken gradually during the next 24 hours.

Typhoon Mawar will move around the western part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the north-northeast during the next 24 hours. On its anticipated track, the center of Typhoon Mawar will pass a little to the east of Miyakojima in 12 hours. Mawar could approach Okinawa in 24 hours. Mawar is likely to be tropical storm when it reaches Okinawa.

Typhoon Mawar Slows South of the Ryukyu Islands

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Typhoon Mawar slowed over the Western North Pacific Ocean south of the Ryukyu Islands on Tuesday. At 11:00 a.m. EDT on Tuesday the center of Typhoon Mawar was located at latitude 20.9°N and longitude 125.0°E which put it about 260 miles (420 km) south of Miyakojima, Japan. Mawar was moving toward the north at 3 m.p.h. (5 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 978 mb.

Typhoon Mawar weakened as it moved slowly toward the Ryukyu Islands on Tuesday. The circulation around Mawar appeared to pull drier air from Asia into the northwestern part of the typhoon. Thunderstorms in bands in the northwestern quadrant of Typhoon Mawar weakened on Tuesday. The northwestern part of the eyewall also weakened. Most of the remaining thunderstorms were occurring in the southern half of Typhoon Mawar. Storms near the center of Mawar’s circulation generated upper level divergence that pumped mass away from the typhoon. The divergence of mass in the upper levels was less than the convergence of mass in the lower levels of Typhoon Mawar and the surface pressure continued to increase.

Even though Typhoon Mawar was weaker, it continued to have a large circulation after several eyewall replacement cycles. Winds to typhoon force extended out 70 miles (110 km) from the center of Mawar. Winds to tropical storm force extended out 225 miles (360 km) from the center of circulation.

Typhoon Mawar will move through an environment that will become less favorable for intensification during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Drier air will persist northwest of Typhoon Mawar. The drier air will inhibit the formation of thunderstorms in the northern half of Mawar’s circulation. In addition, since Typhoon Mawar is moving slowly, winds in the lower levels are likely to mix cooler water to the surface of the Pacific Ocean. The effects of the drier air and mixing of cooler water to the surface of the ocean are likely to cause Typhoon Mawar to weaken gradually during the next 24 hours.

Typhoon Mawar will move around the western part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar slowly toward the north during the next 36 hours. On its anticipated track, the center of Typhoon Mawar will be near Miyakojima in 36 hours. Mawar could be near Okinawa in less than 72 hours.

Typhoon Mawar Moves Toward Southern Ryukyu Islands

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Typhoon Mawar moved toward the southern Ryukyu Islands on Monday morning. At 11:00 a.m. EDT on Monday the center of Typhoon Mawar was located at latitude 19.8°N and longitude 125.5°E which put it about 330 miles (535 km) south of Miyakojima, Japan. Mawar was moving toward the north-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h). The minimum surface pressure was 956 mb.

Typhoon Mawar was in an equilibrium with its environment during much of the past 24 hours. The inner end of a rainband recently wrapped around the existing eye and eyewall and another pair of concentric eyewalls developed. The inner eye had a diameter of 30 miles (50 km). The inner eyewall was surrounded by a clear area, called a moat, and a much larger outer eyewall. Bands of showers and thunderstorms were revolving around the concentric eyewalls. The strongest rainbands were in the southern half of Mawar’s circulation. Storms near the concentric eyewalls generated upper level divergence that pumped mass away from the typhoon. The upper level divergence pumped away an amount of mass that was nearly equal to the mass converging in the lower levels of Mawar’s circulation. Since the upper level divergence was nearly equal to the lower level convergence, Typhoon Mawar maintained a nearly steady intensity during the past 24 hours.

The circulation around Typhoon Mawar continued to be large. Winds to typhoon force extended out 70 miles (110 km) from the center of Mawar’s circulation. Winds to tropical storm force extended out 250 miles (400 km) from the center of Mawar. The Hurricane Intensity Index (HII) for Typhoon Mawar was 20.6. The Hurricane Size Index (HSI) was 21.1 and the Hurricane Wind Intensity Size Index (HWISI) was 41.7. Typhoon Mawar was similar in intensity to Hurricane Rita when Rita hit Southwest Louisiana in 2005. Mawar was a little smaller than Rita was.

Typhoon Mawar will move through an environment favorable for a strong typhoon during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Although the environment is favorable, the formation of concentric eyewalls is likely to start an eyewall replacement cycle that will cause Typhoon Mawar to weaken gradually during the next 24 hours.

Typhoon Mawar will move around the western part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the north during the next 36 hours. The steering winds will weaken as Mawar moves around the western end of the high pressure system. On its anticipated track, Typhoon Mawar will move slowly toward the southern Ryukyu Islands during the next 36 hours.

Typhoon Mawar Moves South of Ryukyu Islands

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Typhoon Mawar moved south of the Ryukyu Islands on Sunday morning. At 5:00 a.m. EDT on Sunday the center of Typhoon Mawar was located at latitude 17.7°N and longitude 125.7°E which put it about 505 miles (815 km) southeast of Ishigakijima, Japan. Mawar was moving toward the west-northwest at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 951 mb.

Typhoon Mawar continued to weaken gradually on Sunday morning as it moved over the Western North Pacific Ocean south of the Ryukyu Islands. A circular eye with a diameter of 20 miles (32 km) was present at the center of Mawar’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Numerous bands of showers and thunderstorms were revolving around the center of Typhoon Mawar. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm in all directions. The upper level divergence was still not removing as much mass as was converging in the lower levels of Mawar’s circulation which caused the surface pressure to continue to increase slowly.

Typhoon Mawar continued to be a large typhoon even though it was gradually weakening. Winds to typhoon force extended out 80 miles (130 km) from the center of Mawar’s circulation. Winds to tropical storm force extended out 250 miles (400 km) from the center of Mawar. The Hurricane Intensity Index (HII) for Typhoon Mawar was 22.1. The Hurricane Size Index (HSI) was 26.6 and the Hurricane Wind Intensity Size Index (HWISI) was 48.7. Typhoon Mawar was similar in size and intensity to Hurricane Jeanne when Jeanne hit South Florida in 2004.

Typhoon Mawar will move through an environment favorable for a strong typhoon during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Although the environment is favorable, Typhoon Mawar will continue to weaken gradually as long as the upper level divergence is removing less mass than is converging in the lower levels. Typhoon Mawar is forecast to continue to weaken during the next 24 hours.

Typhoon Mawar will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the west-northwest during the next 24 hours. Typhoon Mawar will move toward the north when it reaches the western end of the high pressure system early next week. On its anticipated track, Typhoon Mawar will move toward the southern Ryukyu Islands next week.

Typhoon Mawar Weakens a Little

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Typhoon Mawar weakened a little on Saturday as it moved over the Western North Pacific Ocean south of the Ryukyu Islands. At 11:00 a.m. EDT on Saturday the center of Typhoon Mawar was located at latitude 16.9°N and longitude 130.4°E which put it about 650 miles (1050 km) southeast of Ishigakijima, Japan. Mawar was moving toward the west-northwest at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 926 mb.

Typhoon Mawar weakened a little after it went through another eyewall replacement cycle. The previous inner eye and eyewall dissipated. However, a circular eye with a diameter of 30 miles (50 km) was present at the center of Mawar’s circulation. The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Numerous bands of showers and thunderstorms were revolving around the center of Typhoon Mawar. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm in all directions. The upper level divergence was not able to remove as much mass as was converging in the lower levels of Mawar’s circulation which caused the surface pressure to increase slowly.

The recent eyewall replacement cycle caused the size of the circulation around Typhoon Mawar to remain large. Winds to typhoon force extended out 80 miles (130 km) from the center of Mawar’s circulation. Winds to tropical storm force extended out 275 miles (445 km) from the center of Mawar. The Hurricane Intensity Index (HII) for Typhoon Mawar was 31.6. The Hurricane Size Index (HSI) was 30.0 and the Hurricane Wind Intensity Size Index (HWISI) was 61.6. Typhoon Mawar was similar in size and intensity to Hurricane Wilma when Wilma was over the Northwest Caribbean Sea in 2005.

Typhoon Mawar will move through an environment favorable for a powerful typhoon during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Although the environment is favorable, the recent eyewall replacement cycle partially disrupted the inner core of Typhoon Mawar. Since the upper level divergence is removing less mass than is converging in the lower levels, the surface pressure is likely to increase slowly. If the surface pressure continues to increase, Typhoon Mawar will weaken gradually during the next 24 hours.

Typhoon Mawar will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the west-northwest during the next 24 hours. On its anticipated track, Typhoon Mawar could move south of Ishigakijima, Japan in 48 hours.

Typhoon Mawar Moves Southeast of Ryukyu Islands

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Typhoon Mawar moved southeast of the Ryukyu Islands on Friday morning. At 11:00 a.m. EDT on Friday the center of Typhoon Mawar was located at latitude 15.8°N and longitude 135.8°E which put it about 930 miles (1500 km) southeast of Okinawa. Mawar was moving toward the west-northwest at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 165 m.p.h. (270 km/h) and there were wind gusts to 200 m.p.h. (320 km/h). The minimum surface pressure was 910 mb.

Concentric eyewalls formed in the core of Typhoon Mawar on Friday morning and another eyewall replacement cycle was underway. The inner eye had a diameter of 30 miles (50 km). The inner eye was surrounded by a larger, outer eyewall. Bands of showers and thunderstorms were revolving around the concentric eyewalls. Storms near the core of Mawar’s circulation generated strong upper level divergence that pumped mass away from the tropical storm in all directions. The removal of large quantities of mass allowed the surface pressure to remain very low.

The formation of concentric eyewalls caused the size of the circulation around Typhoon Mawar to increase again. Winds to typhoon force extended out 115 miles (185 km) from the center of Mawar’s. Winds to tropical storm force extended out 215 miles (345 km) from the center of Mawar. The Hurricane Intensity Index (HII) for Typhoon Mawar was 36.8. The Hurricane Size Index (HSI) was 33.5 and the Hurricane Wind Intensity Size Index (HWISI) was 70.3. Typhoon Mawar was similar in size and intensity to Hurricane Katrina when Katrina was a Category 5 hurricane on the Saffir-Simpson Scale over the Gulf of Mexico in 2005.

Typhoon Mawar will move through an environment favorable for a powerful typhoon during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Although the environment is favorable, Typhoon Mawar is likely to weaken while the eyewall replacement cycle occurs. The low level inflow will become more concentrated in the larger outer eyewall and the inner eyewall will weaken. Since the strongest winds are occurring in the inner eyewall, Mawar will weaken when the inner eyewall dissipates. Typhoon Mawar could start to strengthen again once the inner eyewall dissipates and the outer eyewall begins to contract around the center of circulation.

Typhoon Mawar will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the west-northwest during the next 24 hours. On its anticipated track, Typhoon Mawar could move southeast of Ishigakijima, Japan in three or four days.