Category Archives: Tropical Cyclones

Information about tropical cyclones

Tropical Storm Jerry Nears Northern Leeward Islands

Tropical Storm Jerry neared the Northern Leeward Islands on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Jerry was located at latitude 17.3°N and longitude 60.6°W which put the center about 175 miles (285 km) east-southeast of the Northern Leeward Islands.  Jerry was moving toward the west-northwest at 18 m.p.h. (30 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 1001 mb.

Tropical Storm Warnings are in effect for Anguilla, Barbuda, St. Barthelemy, St. Martin, Sint Maarten, and Guadeloupe.

Tropical Storm Watches are in effect for Antigua, St. Kitts, Nevis, Montserrat, Saba, and St. Eustatius.

The circulation around Tropical Storm Jerry was still not well organized on Thursday afternoon.  Strong easterly winds in the lower levels of the atmosphere continued to push the bottom part of Tropical Storm Jerry to the northwest of the middle and upper level circulations.  Bands near the center of the low level circulation consisted primarily of showers and lower clouds. The bands in the western and northern sides of Jerry’s circulation also consisted primarily of showers and lower clouds. Thunderstorms were occurring in bands in the southeastern part of Tropical Storm Jerry.

The strongest winds were occurring in the bands of thunderstorms in the southeastern part of Tropical Storm Jerry.  Winds to tropical storm force extended out 175 miles (280 km) in the eastern side of Jerry’s circulation.  Winds to tropical storm force extended out 80 miles (130 km) in the northwestern quadrant of Tropical Storm Jerry.  The winds in the southwestern quadrant of Jerry were blowing at less than tropical storm force.

Tropical Storm Jerry will move through an environment that will be mostly unfavorable for development during the next 24 hours.  Jerry will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level low that is north of Puerto Rico.  The upper level low will produce westerly winds that will blow toward the top of Jerry’s circulation.  Since strong easterly winds are blowing in the lower levels of the atmosphere, there will continue to be strong vertical wind shear.  The strong vertical wind shear will inhibit intensification.  Tropical Storm Jerry could even weaken during the next 24 hours because of the strong vertical wind shear.

Tropical Storm Jerry will move around the southwestern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Jerry toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Jerry will pass near the Northern Leeward Islands on Thursday night.

Tropical Storm Jerry will bring gusty winds and locally heavy rain to the Northern Leeward Islands.  Heavy rain could cause flash floods in some locations.  Since the strongest winds are in the eastern part of Tropical Storm Jerry, the strongest winds may not hit the Northern Leeward Islands.

Tropical Storm Raymond Forms South of Mexico

Tropical Storm Raymond formed over the Eastern North Pacific Ocean south of Mexico on Thursday.  At 2:00 p.m. EDT on Thursday the center of Tropical Storm Raymond was located at latitude 16.1°N and longitude 101.0°W which put the center about 115 miles (185 km) south-southeast of Zihuatanejo, Mexico.  Raymond was moving toward the northwest at 9 m.p.h. (15 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.

A Tropical Storm Watch is in effect for the portion of the coast from Zihuatanejo to Cabo Corrientes, Mexico.

A low pressure system over the Eastern North Pacific Ocean south of Mexico strengthened on Thursday and the U.S. National Hurricane Center designated the system as Tropical Storm Raymond.

The distribution of thunderstorms in Tropical Storm Raymond was asymmetrical.  Thunderstorms were occurring in bands in the southern and western parts of Raymond’s circulation.  Bands in the northern and eastern parts of Tropical Storm Raymond consisted primarily of shower and lower clouds.  Storms near the center of Raymond started to generate upper level divergence that pumped mass away to the west of the tropical storm.

Tropical Storm Raymond will move through an environment that will be somewhat favorable for intensification during the next 24 hours.  Raymond will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is over Mexico.  The upper level ridge will produce easterly winds that will blow toward the top of Raymond’s circulation.  Those winds will cause strong vertical wind shear.  The strong wind shear will inhibit intensification.  Tropical Storm Raymond could intensify a little on Friday if the upper level winds do not get any stronger.

Tropical Storm Raymond will move around the western side of a high pressure system that is over Mexico.  The high pressure system will steer Raymond toward the northwest during the next 24 hours.  On its anticipated track, the center of Tropical Storm Raymond will move near the coast of Mexico between Zihuatanejo and Cabo Corrientes on Friday.

Tropical Storm Raymond will bring gusty winds and locally heavy rain to coastal sections of Colima, Michoacan, and western Guerrero.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Priscilla continued to weaken west of Baja California.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Priscilla was located at latitude 23.8°N and longitude 114.7°W which put the center about 165 miles (265 km) west-southwest of Cabo San Lazaro, Mexico.  Priscilla was moving toward the north-northwest at 8 m.p.h. (13 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 996 mb.

Tropical Storm Jerry Speeds Toward Northern Leeward Islands

Tropical Storm Jerry was speeding toward the Northern Leeward Islands on Wednesday afternoon.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Jerry was located at latitude 14.8°N and longitude 54.7°W which put the center about 605 miles (970 km) east-southeast of the Northern Leeward Islands.  Jerry was moving toward the west-northwest at 23 m.p.h. (37 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 1000 mb.

Tropical Storm Watches are in effect for Antigua, Barbuda, Anguilla, Saba, St. Eustatius, St. Barthelemy, St, Kitts, Nevis, St. Martin, Sint Maarten, Montserrat, and Guadeloupe.

The circulation around Tropical Storm Jerry was not well organized on Wednesday afternoon.  Strong easterly winds in the lower levels of the atmosphere pushed the bottom part of Tropical Storm Jerry to the west of the middle and upper level circulations.  Bands near the center of the low level circulation consisted primarily of showers and lower clouds.  The bands in the western side of Jerry’s circulation also consisted primarily of showers and lower clouds.  Thunderstorms were still developing in bands in the eastern side of Tropical Storm Jerry.

The strongest winds were occurring in the bands of thunderstorms in the eastern side of Tropical Storm Jerry.  Winds to tropical storm force extended out 175 miles (280 km) in the eastern side of Jerry’s circulation.  Winds to tropical storm force extended out 80 miles (130 km) in the northwestern quadrant of Tropical Storm Jerry.  The winds in the southwestern quadrant of Jerry were blowing at less than tropical storm force.

Tropical Storm Jerry will move through an environment that will be marginally favorable for development during the next 24 hours.  Jerry will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern side of an upper level ridge over the tropical Atlantic Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Jerry’s circulation.  However, the stronger easterly winds in the lower levels of the atmosphere will continue to cause vertical wind shear.  The vertical wind shear will inhibit intensification.  Tropical Storm Jerry could intensify during the next 24 hours if the winds in the lower levels of the atmosphere weaken.

Tropical Storm Jerry will move around the southern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Jerry quickly toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Jerry will approach the Northern Leeward Islands on Thursday afternoon.

Tropical Storm Jerry is likely to bring gusty winds and locally heavy rain to the Northern Leeward Islands on Thursday night and Friday.

Typhoon Halong Passes South of Tokyo

Typhoon Halong passed south of Tokyo on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Typhoon Halong was located at latitude 32.8°N and longitude 140.3°E which put the center about 195 miles (315 km) south of Tokyo, Japan.  Halong was moving toward the northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 946 mb.

Typhoon Halong was starting to weaken as it passed south of Tokyo on Wednesday.  A circular eye with a diameter of 25 miles (40 km) was still present at the center of Halong’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 center of Typhoon Halong.  Storms near the center of Halong generated upper level divergence that pumped mass away to the east of the typhoon.  The removal of mass was less than the inflow of mass in the lower levels of the atmosphere.  So, the surface pressure was increasing.

The circulation around Typhoon Halong increased in size on Wednesday.  Winds to typhoon force extended out 40 miles (65 km) from the center of Halong’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Halong.

The Hurricane Intensity Index (HII) for Typhoon Halong was 23.6.  The Hurricane Size Index (HSI) was 13.9 and the Hurricane Wind Intensity Size Index (HWISI) was 37.5.  Typhoon Halong was similar in intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.  Halong is bigger than Dennis was.

Typhoon Halong will move through an environment that will become more unfavorable for intensification during the next 24 hours.  Halong will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the southern extent of the upper level westerly winds in the middle latitudes.  The upper level westerly winds will blow toward the top of Halong’s circulation.  Those winds will cause the vertical wind shear to increase.  Cooler Sea Surface Temperatures and more vertical wind shear will cause Typhoon Halong to weaken during the next 24 hours.  Halong is likely to make a transition to an extratropical cyclone during the next few days.

The upper level westerly winds will steer Typhoon Halong quickly toward the east during the next 24 hours.  On its anticipated track, Typhoon Halong will move away from Japan on Thursday.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nakri former southwest of Iwo To.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Nakri was located at latitude 22.3°N and longitude 136.0°E which put the center about 625 miles (1010 km) south-southeast of Okinawa.  Nakri was moving toward the northwest at 18 m.p.h. (30 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 1000 mb.

Priscilla Weakens to a Tropical Storm

Former Hurricane Priscilla weakened to a tropical storm over the Eastern North Pacific Ocean south of Baja California on Wednesday afternoon.  At 2:00 p.m. EDT on Wednesday the center of Tropical Storm Priscilla was located at latitude 21.7°N and longitude 112.7°W which put the center about 195 miles (310 km) west-southwest of the southern tip of Baja California.  Priscilla was moving toward the northwest at 7 m.p.h. (11 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 985 mb.

A Tropical Storm Watch was in effect for the portion of the coast from Cabo San Lucas to Cabo San Lazaro, Mexico.

Former Hurricane Priscilla rapidly weakened to a tropical storm south of Baja California on Wednesday.  Thunderstorms around the center of Priscilla’s circulation and in the northern half of the circulation weakened.  Bands in those parts of Tropical Storm Priscilla consisted primarily of showers and lower clouds.  Thunderstorms were still occurring in bands in the southern and western periphery of Priscilla’s circulation.  Weakening of the thunderstorms near the core of Tropical Storm Priscilla greatly reduced the upper level divergence.  With much less upper level divergence the inflow of mass in the lower levels of the atmosphere caused the surface pressure to increase.

The circulation around Tropical Storm Priscilla was still large.  Winds to tropical storm force extended out 160 miles (260 km) from the center of Priscilla’s circulation.

Tropical Storm Priscilla will move through an environment that will become even more unfavorable for intensification during the next 24 hours.  Priscilla will move over water where the Sea Surface Temperatures are near 26°C.  An upper level trough near the west coast of the U.S. will produce southwesterly winds that will blow toward the top of Priscilla’s circulation.  Those winds will cause the vertical wind shear to increase.  The effects of cooler water and increasing vertical wind shear will cause Tropical Storm Priscilla to continue to weaken during the next 24 hours.

Tropical Storm Priscilla will move around the western end of a high pressure system over Mexico.  The high pressure system will steer Priscilla toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Priscilla will move west of Cabo San Lazaro on Thursday.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Octave continued to gradually weaken far to the southwest of Baja California.  At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Octave was located at latitude 15.4°N and longitude 116.2.°W which put the center about 660 miles (1065 km) southwest of the southern tip of Baja California.  Octave was moving toward the east 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 1003 mb.

Hurricane Priscilla Starts to Weaken

Hurricane Priscilla started to weaken on Tuesday evening.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Priscilla was located at latitude 20.6°N and longitude 111.5°W which put the center about 190 miles (305 km) south-southwest of the southern tip of Baja California.  Priscilla was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 962 mb.

A Tropical Storm Watch was in effect for the portion of the coast from Cabo San Lucas to Cabo San Lazaro, Mexico.

Hurricane Priscilla started to weaken on Tuesday evening after Priscilla had strengthened to Category 2 on the Saffir-Simpson Scale earlier in the day.  Hurricane Priscilla appeared to have mixed cooler water to the surface of the Eastern North Pacific Ocean.  A large eye with a diameter of 50 miles (80 km) was still present at the center of Priscilla’s circulation.  However, the ring of thunderstorms surrounding the eye was broken in several places.  Also, many of the thunderstorms in bands in the eastern side of Hurricane Priscilla had weakened.  The bands in the eastern part of Priscilla’s circulation consisted primarily of showers and lower clouds.  Thunderstorms were still occurring in bands in the western half of Hurricane Priscilla.

The circulation around Hurricane Priscilla was still large.  Winds to hurricane force extended out 45 miles (75 km) from the center of Priscilla’s circulation.  Winds to tropical storm force extended out 195 miles (315 km) from the center of Hurricane Priscilla.

The Hurricane Intensity Index (HII) for Hurricane Priscilla was 17.8.  The Hurricane Size Index (HSI) was 17.1 and the Hurricane Wind Intensity Size Index (HWISI) was 34.9.

Hurricane Priscilla will move through an environment that will become more unfavorable for intensification during the next 24 hours.  An upper level trough near the west coast of the U.S. will start to produce southwesterly winds that will blow toward the top of Priscilla’s circulation.  Those winds will cause the vertical wind shear to begin to increase.  In addition, the cooler water mixed to the surface of the ocean by Priscilla’s winds will limit the energy transfer from the ocean to the atmosphere.  The effects of cooler water and increasing vertical wind shear will cause Hurricane Priscilla to weaken during the next 24 hours.

Hurricane Priscilla will move around the western end of a high pressure system over Mexico.  The high pressure system will steer Priscilla toward the north-northwest during the next 24 hours.  On its anticipated track, Hurricane Priscilla will move parallel to the coast of southwestern Baja California on Wednesday.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Octave weakened far to the southwest of Baja California.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Octave was located at latitude 15.2°N and longitude 118.0.°W which put the center about 750 miles (1205 km) southwest of the southern tip of Baja California.  Octave was moving toward the east 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 1000 mb.

Tropical Storm Jerry Forms East of Leeward Islands

Tropical Storm Jerry formed east of the Leeward Islands on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Jerry was located at latitude 11.5°N and longitude 44.6°W which put the center about 1315 miles (2120 km) east-southeast of the Northern Leeward Islands.  Jerry was moving toward the west at 24 m.p.h. (39 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 1006 mb.

A low pressure system over the tropical Atlantic Ocean east of the Leeward Islands strengthened on Tuesday morning and the U.S. National Hurricane Center designated the system at Tropical Storm Jerry.

Tropical Storm Jerry was strengthening on Tuesday morning.  More thunderstorms developed near the center of Jerry’s circulation.  Bands of showers and thunderstorms were revolving around the center of Tropical Storm Jerry.  Storms near the center of Jerry started to generate upper level divergence that pumped mass away from the tropical storm.

The strongest winds were occurring in the eastern side of Tropical Storm Jerry.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Jerry’s circulation.   The winds in the western side of Tropical Storm Jerry were blowing at less than tropical storm force.

Tropical Storm Jerry will move through an environment favorable for intensification during the next 24 hours.  Jerry will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern side of an upper level ridge over the tropical Atlantic Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Jerry’s circulation.  However, the winds in the lower levels of the atmosphere will also blow from the east.  So, there will be less vertical wind shear.  Tropical Storm Jerry will intensify during the next 24 hours.  Jerry is likely to strengthen to a hurricane later this week.

Tropical Storm Jerry will move around the southern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Jerry quickly toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Jerry will approach the Northern Leeward Islands on Thursday.

Typhoon Halong Intensifies to Equivalent of a Major Hurricane

Typhoon Halong intensified to the equivalent of a major hurricane over the Western North Pacific Ocean south of Japan on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Halong was located at latitude 28.4°N and longitude 137.2°E which put the center about 490 miles (785 km) south-southwest of Tokyo, Japan.  Halong was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 942 mb.

Typhoon Halong intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Tuesday morning.  A circular eye with a diameter of 40 miles (65 km) was at the center of Halong’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 Halong.  Storms near the core of Halong generated upper level divergence that pumped mass away from the typhoon in all directions.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Halong was relatively small.  Winds to typhoon force extended out 30 miles (50 km) from the center of Halong’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Halong.

The Hurricane Intensity Index (HII) for Typhoon Halong was 25.1.  The Hurricane Size Index (HSI) was 10.2 and the Hurricane Wind Intensity Size Index (HWISI) was 35.3.  Typhoon Halong was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon Halong will move through an environment that is favorable for intensification during the next 24 hours.  Halong will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge that is south of Japan.  The upper level winds are weak near the middle of the upper level ridge and there will be little vertical wind shear.  Typhoon Halong will intensify during the next 24 hours.

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

Hurricane Priscilla Moves South of Baja California

Hurricane Priscilla moved south of Baja California on Monday night.  At 11:00 p.m. EDT on Monday the center of Hurricane Priscilla was located at latitude 19.1°N and longitude 108.5°W which put the center about 275 miles (445 km) south-southeast of the southern tip of Baja California.  Priscilla was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 972 mb.

A Tropical Storm Watch was in effect for the portion of the coast from Cabo San Lucas to Cabo San Lazaro, Mexico.

Hurricane Priscilla was showing evidence of intensification on Monday evening.  New tall thunderstorms were forming just to the south of the center of Priscilla’s circulation.  Microwave satellite imagery was indicating that an eye might be forming at the center of Hurricane Priscilla.  Bands of showers and thunderstorms were revolving around the center.  Storms near the center of Priscilla generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The circulation around Hurricane Priscilla was very large.  Winds to hurricane force extended out 50 miles (80 km) in the eastern side of Priscilla’s circulation.  Winds to hurricane force extended out 25 miles (40 km) in the western side of Priscilla.  Winds to tropical storm force extended out 185 miles (295 km) from the center of Hurricane Priscilla.

Hurricane Priscilla will move through an environment favorable for intensification during the next 24 hours.  Priscilla will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the middle of an upper level ridge over Mexico and the Eastern North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Priscilla will intensify during the next 24 hours.  Priscilla could strengthen to a major hurricane on Tuesday.

Hurricane Priscilla will move around the western end of a high pressure system over Mexico.  The high pressure system will steer Priscilla slowly toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Priscilla will move closer to the southern part of Baja California on Tuesday.

Elsewhere over the Eastern North Pacific Ocean, former Hurricane Octave weakened back to a tropical storm on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Octave was located at latitude 15.8°N and longitude 120.4°W which put the center about 840 miles (1355 km) southwest of the southern tip of Baja California.  Octave was moving toward the east-southeast at 7 m.p.h. (11 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 998 mb.

Halong Strengthens to a Typhoon

Former Tropical Storm Halong strengthened to a typhoon west of the Ogasawara Islands south of Japan on Sunday night.  At 5:00 a.m. EDT on Monday the center of Typhoon Halong was located at latitude 25.9°N and longitude 140.5°E which put the center about 665 miles (1075 km) south of Tokyo, Japan.  Halong 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 977 mb.

Former Tropical Storm Halong strengthened to a typhoon on Sunday night.  A small circular eye formed at the center of Halong’s circulation.  The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were also occurring in bands in the eastern side of Typhoon Halong.  Bands in the western side of Halong’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Halong generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The distribution of wind speeds in Typhoon Halong was relatively symmetrical.  Winds to typhoon force extended out 25 miles (40 km) from the center of Halong’s circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Typhoon Halong.

Typhoon Halong will move through an environment that is mostly favorable for intensification during the next 24 hours.  Halong will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge that is south of Japan.  The upper level winds are weak near the middle of the upper level ridge and there will be little vertical wind shear.  However, Halong will move into a region of drier air.  The drier air will inhibit the formation of thunderstorms in the western part of Halong’s circulation.  Typhoon Halong is likely to intensify during the next 24 hours if the drier air does not get pulled into the core of Halong.

Typhoon Halong will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Halong toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Halong will move a little closer to Japan.

Elsewhere, the center of Tropical Storm Matmo moved over northeastern Vietnam.  At 5:00 a.m. EDT on Monday the center of Tropical Storm Matmo was located at latitude 22.4°N and longitude 106.2°E which put the center about 25 miles (40 km) east of Na Phac, Vietnam.  Matmo was moving toward the west-northwest at 13 m.p.h. (21 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.