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Tropical Depression Pulasan Moves Near Shanghai

Tropical Depression Pulasan moved near Shanghai on Thursday.  At 11:00 a.m. EDT on Thursday the center of Tropical Depression Pulasan was located at latitude 30.8°N and longitude 121.6°E which put the center about 50 miles (80 km) south-southeast of Shanghai, China.  Pulasan was moving toward the 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 998 mb.

Former Tropical Storm Pulasan weakened to a tropical depression as it approached Shanghai on Thursday.  Pulasan brought gusty winds and heavy rain to the region around Shanghai.

The distribution of thunderstorms in Tropical Depression Pulasan was asymmetrical.  Thunderstorms were occurring in bands in the northern side of Pulasan’s circulation.  The bands in the southern side of the circulation consisted primarily of showers and lower clouds.

Tropical Depression Pulasan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Pulasan toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Depression Pulasan will move north of Shanghai.

Tropical Storm Pulasan will continue to bring gusty winds and locally heavy rain to the area north of Shanghai during the next 12 hours.  Heavy rain could cause floods in some locations.

Tropical Storm Pulasan Forms Southeast of Ryukyu Islands

Tropical Storm Pulasan formed over the Western North Pacific Ocean southeast of the Ryukyu Islands on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Pulasan was located at latitude 19.3°N and longitude 137.8°E which put the center about 450 miles (725 km) south-southwest of Iwo To.  Pulasan was moving toward the west-northwest at 22 m.p.h. (35 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 997 mb.

The circulation around Tropical Storm Pulasan was very large, but there were not many thunderstorms present.  Bands revolving around the center of Pulasan’s circulation consisted primarily of showers and lower clouds.  Thunderstorms were occurring in a band in the far eastern periphery of Tropical Storm Pulasan.  Thunderstorms were also occurring in a band in the far southern periphery of Pulasan’s circulation.

The circulation around Tropical Storm Pulasan was very large, but the distribution of wind speeds was asymmetrical.  Winds to tropical storm force extended out 265 miles (425 km) in the eastern side of Pulasan’s circulation.  The winds in the western side of Tropical Storm Pulasan were blowing at less than tropical storm force.

Tropical Storm Pulasan will move through an environment marginally favorable for intensification during the next 24 hours.  Pulasan will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the eastern side of a large upper level low centered east of Taiwan.  The upper level low will produce southwesterly winds that will blow toward the top of Pulasan’s circulation.  Those winds will cause strong vertical wind shear.  The strong wind shear will inhibit intensification.  Tropical Storm Pulasan could intensify a little during the next 24 hours if the wind shear does not get any stronger.

Tropical Storm Pulasan will move around the northern side of a large counterclockwise circulation sometimes called a monsoon gyre.  The large counterclockwise circulation will steer Pulasan quickly toward the west-northwest during the next 36 hours.  On its anticipated track Tropical Storm Pulasan will be near the Ryukyu Islands in 36 hours.

Tropical Storm Pulasan will bring gusty winds and locally heavy rain to the Ryukyu Islands.  Heavy rain could cause flash floods in some locations.

Elsewhere, former Typhoon Bebinca weakened to a tropical depression over eastern China.  At 11:00 p.m. EDT on Monday the center of Tropical Depression Bebinca was located at latitude 32.0°N and longitude 117.0°E which put the center about 100 miles (160 km) west of Nanjing, China.  Bebinca was moving toward the west-northwest at 12 m.p.h. (19 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 1004 mb.

Typhoon Bolaven Passes East of Iwo To

Typhoon Bolaven passed east of Iwo To on Thursday evening. At 11:00 p.m. EDT on Thursday the center of Typhoon Bolaven was located at latitude 26.2°N and longitude 147.8°E which put it about 350 miles (570 km) east of Iwo To. Bolaven was moving toward the northeast at 23 m.p.h. (37 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (285 km/h). The minimum surface pressure was 928 mb.

Concentric eyewalls developed at the center of Typhoon Bolaven on Thursday. The inner end of a rainband wrapped around the existing small eye and eyewall. The larger outer eyewall surrounded the inner eye and eyewall. Bands of showers and thunderstorms revolved around the concentric eyewalls. Storms near the eyewalls generated upper level divergence that pumped mass away to the northeast of the typhoon.

The size of Typhoon Bolaven increased when the concentric eyewalls developed. Winds to typhoon force extended out 60 miles (95 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 265 miles (425 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 29.9. The Hurricane Size Index (HSI) was 21.3 and the Hurricane Wind Intensity Size Index (HWISI) was 51.2.

Typhoon Bolaven will move through an environment that will become more unfavorable for a powerful typhoon during the next 24 hours. Bolaven will move over water where the Sea Surface Temperatures are near 27°C. It will move under the eastern side of an upper level trough near Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Bolaven’s circulation. Those winds will cause the vertical wind shear to increase. Typhoon Bolaven is likely to weaken during the next 24 hours as it goes through an eyewall replacement cycle and the vertical wind shear increases. Bolaven could make a transition to a strong extratropical cyclone when it moves over cooler water south of Alaska.

The upper level trough near Japan will steer Typhoon Bolaven quickly toward the northeast during the next 24 hours. On its anticipated track, Typhoon Bolaven will pass far to the east of Japan on Friday. Bolaven could move south of the Aleutian Islands during the weekend.

Typhoon Bolaven Gets Even Stronger

Typhoon Bolaven got even stronger on Wednesday morning. At 11:00 a.m. EDT on Wednesday the center of Typhoon Bolaven was located at latitude 19.3°N and longitude 142.9°E which put it about 420 miles (675 km) south-southeast of Iwo To. Bolaven was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 180 m.p.h. (290 km/h) and there were wind gusts to 220 m.p.h. (355 km/h). The minimum surface pressure was 904 mb.

Typhoon Bolaven grew even more powerful on Wednesday morning. A circular eye with a diameter of 16 miles (26 km) was at the center of Bolaven’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Bolaven. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass caused the surface pressure to decrease to 904 mb.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 45 miles (65 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 195 miles (315 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 42.2. The Hurricane Size Index (HSI) was 18.4 and the Hurricane Wind Intensity Size Index (HWISI) was 60.6. Typhoon Bolaven was similar in intensity to Hurricane Dorian in 2019. Bolaven was bigger than Dorian was.

Typhoon Bolaven will move through an environment favorable for a very powerful typhoon during the next 24 hours. Bolaven 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 Bolaven could maintain its intensity during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north during the next 24 hours. On its anticipated track, the Typhoon Bolaven will move closer to Iwo To.

Typhoon Bolaven Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Tuesday evening. At 11:00 p.m. EDT on Tuesday the center of Typhoon Bolaven was located at latitude 17.5°N and longitude 143.8°E which put it about 245 miles (390 km) north-northwest of Guam. Bolaven was moving toward the north-northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 920 mb.

Typhoon Warnings were in effect for Rota, Tinian and Saipan. Tropical Storm Warnings were in effect for Agrihan, Pagan and Alamagan.

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane west of the Marianas on Tuesday evening. A small circular eye with a diameter of 14 miles (22 km) was at the center of Bolaven’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 25 miles (40 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 35.0. The Hurricane Size Index (HSI) was 11.5 and the Hurricane Wind Intensity Size Index (HWISI) was 46.5.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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 Bolaven could continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north-northwest during the next 24 hours. On its anticipated track, the Typhoon Bolaven will stay west of the Marianas during the next 24 hours.

Typhoon Bolaven Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Bolaven rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean north of Guam on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Typhoon Bolaven was located at latitude 16.4°N and longitude 144.3°E which put it about 100 miles (160 km) northwest of Tinian. Bolaven was moving toward the north-northwest at 11 m.p.h. (17 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. (230 km/h). The minimum surface pressure was 959 mb.

A Typhoon Warning was in effect for Rota, Tinian and Saipan. A Typhoon Watch was in effect for Guam. A Tropical Storm Warning was in effect for Guam.

Typhoon Bolaven brought strong winds and heavy rain to Guam, Rota, Tinian and Saipan. The center of Bolaven passed between Rota and Tinian and the strongest winds likely occurred in those places. A weather station in Saipan reported a sustained wind speed of 49 m.p.h. (79 km/h) and a wind gust of 68 m.p.h. (110 km/h). A weather station at Guam International Airport reported a sustained wind speed of 32 m.p.h. (52 km/h) and a wind gust of 46 m.p.h. (74 km/h). That weather station also measured 4.54 inches (115.3 mm) of rain.

Typhoon Bolaven began to intensify rapidly as it moved west of the Marianas. A small circular eye with a diameter of 14 miles (22 km) developed at the center of Bolaven’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Bolaven increased when it intensified on Tuesday. Winds to typhoon force extended out 25 miles (40 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 20.6. The Hurricane Size Index (HSI) was 11.5 and the Hurricane Wind Intensity Size Index (HWISI) was 32.1.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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 Bolaven will intensify during the next 24 hours. Bolaven could intensify rapidly at times. Typhoon Bolaven could strengthen to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north-northwest during the next 24 hours. On its anticipated track, the Typhoon Bolaven will stay west of the Marianas during the next 24 hours.

Bolaven Strengthens to a Typhoon East of Guam

Former Tropical Storm Bolaven strengthened to a typhoon east of Guam on Monday night. At 11:00 p.m. EDT on Monday the center of Typhoon Bolaven was located at latitude 14.0°N and longitude 146.0°E which put it about 110 miles (175 km) east of Guam. Bolaven was moving toward the northwest 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.

A Typhoon Warning was in effect for Rota, Tinian and Saipan. A Typhoon Watch was in effect for Guam. A Tropical Storm Warning was in effect for Guam.

Former Tropical Storm Bolaven strengthened to a typhoon as it neared the Marianas on Monday night. A circular eye formed at the center of Bolaven’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Bolaven increased when it intensified on Monday. Winds to typhoon force extended out 35 miles (55 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 140 miles (220 km) from the center of circulation.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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 Bolaven will intensify during the next 24 hours. Bolaven could intensify rapidly at times.

Typhoon Bolaven will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the northwest during the next 24 hours. On its anticipated track, the center Typhoon Bolaven will pass near Rota in a few hours.

Typhoon Bolaven will bring strong winds and heavy rain to Rota, Tinian and Saipan. The strongest winds are likely to occur in Rota and Tinian. Bolaven will also produce gusty winds and heavy rain in Guam. The strong winds will be capable of causing damage and electricity outages are likely. Heavy rain will cause flash floods in some locations.

Tropical Storm Bolaven Moves Toward the Marianas

Tropical Storm Bolaven moved toward the Marianas on Sunday night. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Bolaven was located at latitude 11.1°N and longitude 149.9°E which put it about 410 miles (660 km) east-southeast of Guam. Bolaven was moving toward the west-northwest at 10 m.p.h. (16 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 992 mb.

A Typhoon Watch was in effect for Guam, Rota, Tinian and Saipan. A Tropical Storm Warning was also in effect for Guam.

Tropical Storm Bolaven strengthened on Sunday. The inner end of a rainband wrapped around the center of Bolaven’s circulation. Bands of showers and thunderstorms revolved 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 70 miles (100 km) from the center of Bolaven.

Tropical Storm Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds that will blow toward the top of Bolaven’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification. Tropical Storm Bolaven is likely to intensify to a typhoon during the next 24 hours.

Tropical Storm Bolaven will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Bolaven will move closer to the Marianas. Bolaven could reach the Marianas in less than 36 hours. Bolaven will very likely be a typhoon when it reaches the Marianas.

Elsewhere over the Western North Pacific Ocean, former Typhoon Koinu made landfall on the coast of China west of Hong Kong on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Koinu was located at latitude 21.5°N and longitude 112.9°E which put it about 75 miles (120 km) west-southeast of Hong Kong. Koinu was moving toward the west at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 988 mb.

Typhoon Koinu Lingers Near Hong Kong

Typhoon Koinu lingered over the Western North Pacific Ocean near Hong Kong on Saturday. At 11:00 p.m. EDT on Saturday the center of Typhoon Koinu was located at latitude 21.4°N and longitude 114.4°E which put it about 65 miles (105 km) south-southeast of Hong Kong. Koinu was moving toward the west-northwest at 4 m.p.h. (6 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 968 mb.

Typhoon Koinu weakened gradually on Saturday as it lingered near Hong Kong. Since Koinu moved very slowly, the strong winds in the lower atmosphere mixed cooler water to the surface of the ocean. Koinu was unable to extract as much energy from the cooler water and the typhoon weakened. Thunderstorms in Typhoon Koinu did not rise quite as high into the atmosphere.

Even though Typhoon Koinu weakened on Saturday, it still exhibited a well organized circulation. A very small eye was present at the center of Koinu’s circulation. The inner end of a rainband wrapped around the existing eye and eyewall, and concentric eyewalls could be developing. Bands of showers and thunderstorms revolved around the small core of Typhoon Koinu. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Koinu decreased as Koinu gradually weakened. Winds to typhoon force extended out 25 miles (40 km) from the center of Koinu’s circulation. Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Koinu was 16.5. The Hurricane Size Index (HSI) was 8.6. and the Hurricane Wind Intensity Size Index (HWISI) was 25.1.

Typhoon Koinu will move through an environment somewhat unfavorable for intensification during the next 24 hours. Koinu will move over water where the Sea Surface Temperatures are near 27°C. It will move under axis of an upper level ridge over China. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. However, strong winds in the lower atmosphere will continue to mix cooler water to the surface of the ocean. In addition, the circulation around the northern side of Typhoon Koinu could draw in some drier air from China. Typhoon Koinu is likely to continue to weaken gradually during the next 24 hours due to the mix of cooler water to the surface of the ocean.

Typhoon Koinu will move will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu slowly toward the west during the next 24 hours. On its anticipated track the center Typhoon Koinu will move south of Hong Kong on Sunday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 15W strengthened to Tropical Storm Bolaven east-southeast of Guam. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Bolaven was located at latitude 9.6°N and longitude 152.9°E which put it about 630 miles (1020 km) east-southeast of Guam. Bolaven was moving toward the west-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 1000 mb. Typhoon Watches were in effect for Guam, Rota, Tinian and Saipan.

Typhoon Koinu Moves Southeast of Hong Kong

Typhoon Koinu moved southeast of Hong Kong on Friday night. At 11:00 p.m. EDT on Friday the center of Typhoon Koinu was located at latitude 21.1°N and longitude 115.3°E which put it about 115 miles (185 km) southeast of Hong Kong. Koinu was moving toward the west-southwest at 4 m.p.h. (6 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 952 mb.

Typhoon Koinu intensified back to the equivalent of a major hurricane over the South China Sea southeast of Hong Kong on Friday. A circular eye with a diameter of 12 miles (19 km) was at the center of Koinu’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms revolved around the core of Typhoon Koinu. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

Wins to typhoon force extended out 40 miles (65 km) from the center of Typhoon Koinu. Winds to tropical storm force extended out 285 miles (460 km) in the northeast quadrant of Koinu’s circulation. Winds to tropical storm force extended out 130 miles (210 km) in the other parts of Typhoon Koinu. The Hurricane Intensity Index (HII) for Typhoon Koinu was 22.1. The Hurricane Size Index (HSI) was 14.9 and the Hurricane Wind Intensity Size Index (HWISI) was 37.0. Typhoon Koinu was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon Koinu will move through an environment somewhat favorable for a strong typhoon during the next 24 hours. Koinu will move over water where the Sea Surface Temperatures are near 28°C. It will move under the southern part of an upper level ridge over China. The ridge will produce easterly winds that will blow toward the top of Koinu’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification. The circulation around the northern side of Typhoon Koinu could draw in some drier air from China. Typhoon Koinu could maintain its intensity during the next 24 hours if the drier air does not reach the inner core of the circulation. Koinu is likely to weaken if the drier penetrates to the core of the circulation.

Typhoon Koinu will move will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu slowly toward the west-southwest during the next 24 hours. On its anticipated track the center Typhoon Koinu will move south of Hong Kong on Saturday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 15W formed east-southeast of Guam. At 11:00 p.m. EDT on Friday the center of Tropical Depression 15W was located at latitude 9.9°N and longitude 154.2°E which put it about 700 miles (1130 km) east-southeast of Guam. The tropical depression was moving toward the west-northwest at 13 m.p.h. (21 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.