Tag Archives: Saipan

Typhoon In-Fa Moves Toward Northern Marianas

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Typhoon In-Fa continued to move toward the Northern Marianas on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Typhoon In-Fa was located at latitude 16.1°N and longitude 153.8°E which put the center about 565 miles (910 km) east of Saipan.  In-Fa was moving toward the west-northwest at 18 m.p.h. (30 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 951 mb.

Typhoon In-Fa did not change much on Wednesday.  A circular eye with a diameter of 40 miles (65 km) was at the center of In-Fa’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 In-Fa.  Storms near the center of In-Fa generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure did not change much on Wednesday.

The distribution of wind speeds in Typhoon In-Fa was very symmetrical.  Winds to typhoon force extended out 50 miles (80 km) from the center of In-Fa’s circulation.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Typhoon In-Fa.

The Hurricane Intensity Index (HII) for Typhoon In-Fa is 25.1.  The Hurricane Size Index (HSI) is 18.1 and the Hurricane Wind Intensity Size Index (HWISI) is 43.2.  Typhoon In-Fa is similar in size to Hurricane Ian when Ian hit Southwest Florida in 2022.  In-Fa is not as strong as Ian was.

Typhoon In-Fa will move through an environment that will be favorable for a strong typhoon 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 appears to be in a near equilibrium with its environment.  In-Fa is likely to maintain its intensity during the next 24 hours.

Typhoon In-Fa will move around the southern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer In-Fa toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon In-Fa will approach Alamagan, Pagan, and Agrihan in 24 hours.

Typhoon In-Fa will be the equivalent of a major hurricane when it reaches Alamagan, Pagan, and Agrihan.  In-Fa will bring strong winds and heavy rain to those islands.  Heavy rain is likely to cause flash floods.

Typhoon In-Fa Churns Westward

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Typhoon In-Fa continued to churn westward over the Western North Pacific Ocean east of the Northern Marianas on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Typhoon In-Fa was located at latitude 15.0°N and longitude 159.3°E which put the center about 940 miles (1515 km) east of Saipan.  In-Fa was moving toward the west-northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 945 mb.

An eyewall replacement cycle occurred in the core of Typhoon In-Fa on Tuesday.  The original eye and eyewall disappeared by Tuesday evening.  A new eye with a diameter of 40 miles (65 km) was at the center of In-Fa’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 In-Fa.  Storms near the center of In-Fa generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure did not change much on Tuesday.

The distribution of wind speeds in Typhoon In-Fa was very symmetrical.  Winds to typhoon force extended out 45 miles (75 km) from the center of In-Fa’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon In-Fa.

The Hurricane Intensity Index (HII) for Typhoon In-Fa is 28.3.  The Hurricane Size Index (HSI) is 17.1 and the Hurricane Wind Intensity Size Index (HWISI) is 45.4. Typhoon In-Fa is similar in size to Hurricane Ian when Ian hit Southwest Florida in 2022.  In-Fa is not quite as strong as Ian was.

Typhoon In-Fa will move through an environment that will be 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 could intensify during the next 24 hours unless another eyewall replacement cycle occurs.

Typhoon In-Fa will move around the southern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer In-Fa toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon In-Fa will continue to move toward the Northern Marianas.

Typhoon In-Fa Rapidly Intensifies to Equivalent of a Major Hurricane

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Typhoon In-Fa rapidly intensified to the equivalent of a major hurricane on Monday over the Western North Pacific Ocean east of the Northern Marianas.  At 11:00 a.m. EDT on Monday the center of Typhoon In-Fa was located at latitude 14.1°N and longitude 162.6°E which put the center about 1135 miles (1830 km) east of Saipan.  In-Fa was moving toward the west-northwest at 4 m.p.h. (6 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 946 mb.

Typhoon In-Fa rapidly intensified to the equivalent of a major hurricane on Monday.  A small circular eye with a diameter of 8 miles (13 km) formed at the center of In-Fa’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 In-Fa.  Storms near the center of In-Fa generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon In-Fa was small.  Winds to typhoon force extended out 30 miles (50 km) from the center of In-Fa’s circulation.  Winds to tropical storm force extended out 80 miles (130 km) from the center of Typhoon In-Fa.

The Hurricane Intensity Index (HII) for Typhoon In-Fa is 25.1.  The Hurricane Size Index (HSI) is 9.6 and the Hurricane Wind Intensity Size Index (HWISI) is 34.7.  Typhoon In-Fa is similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon In-Fa will move through an environment that will be 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 could continue to intensify during the next 24 hours unless the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form, then an eyewall replacement cycle could cause In-Fa to weaken.

Typhoon In-Fa will move around the southern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer In-Fa toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon In-Fa will move toward the Northern Marianas.

 

Typhoon Champi Brings Wind and Rain to Guam

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Typhoon Champi brought wind and rain to Guam on Saturday.  At 5:00 p.m. EDT on Saturday the center of Typhoon Champi was located at latitude 13.2°N and longitude 144.3°E which put the center about 40 miles (65 km) south of Guam.  Champi was moving toward the west-northwest at 16 m.p.h. (26 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 934 mb.

Typhoon Warnings are in effect for Guam and Rota,

Tropical Storm Warnings are in effect for Tinian and Saipan.

The core of Typhoon Champi where the strongest winds are occurring passed just to the south of Guam on Saturday.  Bands in the northern side of Champi’s circulation brought strong winds and rain to Guam, Rota, Tinian and Saipan.

A weather station at the Guam International Airport (PGUM) reported a sustained wind speed of 47 m.p.h. (76 km/h) and a wind gust of 72 m.p.h. (116 km/h).

A weather station at Andersen Air Force Base (PGUA) reported a sustained wind speed 0f 46 m.p.h. (74 km/h) and a wind gust of 59 m.p.h. (95 km/h).

Typhoon Champi was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  Winds to typhoon force extended out 60 miles (95 km) from the center of Champi’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Champi.

The Hurricane Intensity Index (HII) for Typhoon Champi is 31.6.  The Hurricane Size Index (HSI) is 18.6 and the Hurricane Wind Intensity Size Index (HWISI) is 50.2.  Typhoon Champi is similar in size and intensity to Hurricane Laura when Laura hit Southwest Louisiana in 2020.

Typhoon Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Champi will move away from Guam on Sunday.

Typhoon Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi 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 that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Typhoon Champi could intensify during the next 24 hours unless the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form and an eyewall replacement cycle occurs, Champi will weaken, at least temporarily.

Typhoon Champi Rapidly Intensified to Equivalent of Major Hurricane

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Typhoon Champi rapidly intensified to the equivalent of a major hurricane as it moved closer to Guam on Friday night.  At 5:00 a.m. EDT on Saturday the center of Typhoon Champi was located at latitude 12.6°N and longitude 146.7°E which put the center about 180 miles (295 km) east-southeast of Guam.  Champi was moving toward the west at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 948 mb.

Typhoon Warnings are in effect for Guam and Rota,

Tropical Storm Warnings are in effect for Tinian and Saipan.

Typhoon Champi rapidly intensified to the equivalent of a major hurricane on Friday night.  A small circular eye with a diameter of 6 miles (10 km) was at the center of Champi’s circulation. Bands of showers and thunderstorms were revolving around the the center of Typhoon Champi.  Storms near the center of Champi 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 speed became more symmetrical when Typhoon Champi rapidly intensified.  Winds to typhoon force extended out 60 miles (95 km) from the center of Champi’s circulation.  Winds to tropical storm force extended out 130 miles (210 km) from the center of Typhoon Champi.

The Hurricane Intensity Index (HII) for Typhoon Champi is 25.1.  The Hurricane Size Index (HSI) is 18.5 and the Hurricane Wind Intensity Size Index (HWISI) is 43.6.  Typhoon Champi is similar in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Champi is bigger than Harvey was.

Typhoon Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi 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 that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear. The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Typhoon Champi will intensify during the next 24 hours.  Champi could strengthen to the equivalent of a Category 5 hurricane on Saturday.

Typhoon Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Champi will reach Guam in less than 12 hours.

Typhoon Champi is could be the equivalent of a Category 5 hurricane when it reaches Guam.  Champi will bring strong winds and heavy rain to Guam, Rota, Tinian and Saipan.  The strongest winds and heaviest rain are likely to affect Guam and Rota.  Typhoon Champi will be capable of causing severe damage in Guam.  Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian and Saipan.

Champi Strengthens to a Typhoon East of Guam

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Former Tropical Storm Champi strengthened to a typhoon east of Guam on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Champi was located at latitude 12.0°N and longitude 149.6°E which put the center about 375 miles (610 km) east-southeast of Guam.  Champi was moving toward the west-northwest at 15 m.p.h. (24 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 984 mb.

Typhoon Warnings are in effect for Guam and Rota,

Tropical Storm Warnings are in effect for Tinian and Saipan.

Former Tropical Storm Champi strengthened to a typhoon on Friday.  The inner end of a rainband wrapped around the center of Typhoon Champi.  A small circular eye formed at the center of Champi’s circulation.  Bands of showers and thunderstorms were revolving around the the center of Typhoon Champi.  Storms near the center of Champi generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the northern side of Typhoon Champi.  Winds to typhoon force extended out 30 miles (50 km) in the northern half of Champi’s circulation.  Winds to tropical storm extended out 100 miles (160 km) from the center of Typhoon Champi.

Typhoon Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi 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 that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear. The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Typhoon Champi will intensify during the next 24 hours.  Champi could strengthen to the equivalent of a major hurricane on Saturday.

Typhoon Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Champi will reach Guam in 24 hours.

Typhoon Champi is could be the equivalent of a major hurricane when it reaches Guam.  Champi is likely to bring strong winds and heavy rain to Guam, Rota, Tinian and Saipan.  The strongest winds and heaviest rain are likely to affect Guam and Rota.  Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian and Saipan.

Tropical Storm Champi Forms east of Guam

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Tropical Storm Champi formed over the Western North Pacific Ocean east of Guam on Thursday.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Champi was located at latitude 11.6°N and longitude 155.8°E which put the center about 795 miles (1285 km) east of Guam.  Champi was moving toward the west-northwest at 12 m.p.h. (19 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 999 mb.

Typhoon Watches are in effect for Guam, Rota, Tinian, and Saipan.

A low pressure system over the Western North Pacific Ocean east of Guam strengthened on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Champi.

Even though Tropical Storm Champi was strengthening on Thursday, the distribution of thunderstorms in Champi was asymmetrical.  Thunderstorms were occurring in bands in the western and southern parts of Champi’s circulation.  Bands in the eastern and southern parts of Tropical Storm Champi consisted primarily of showers and lower clouds.  Storms near the center of Champi began to generate upper level divergence that pumped mass away to the west of the tropical storm.  The removal of mass caused the surface pressure to start to decrease.

The distribution of wind speeds in Tropical Storm Champi was also asymmetrical.  Winds to tropical storm force extended out 85 miles (135 km) in the southern half of Champi’s circulation.  The winds in the northern part of Tropical Storm Champi were blowing at less than tropical storm force.

Tropical Storm Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi 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 that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear will inhibit intensiciation, but the wind shear will not be enough to prevent intensification.  Tropical Storm Champi will intensify during the next 24 hours.  Champi could strengthen to a typhoon by Friday night.

Tropical Storm Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Champi will move toward the Marianas.  Champi could reach the Marianas in 48 hours.

Tropical Storm Champi is likely to be a typhoon when it reaches the Marianas.  Champi is likely to bring strong winds and heavy rain to Guam, Rota, Tinian and Saipan.  Heavy rain is likely to cause flash floods in some locations.

Typhoon Koguma Intensifies to Equivalent of a Major Hurricane

Typhoon Koguma intensified to the equivalent of a major hurricane east of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Koguma was located at latitude 20.5°N and longitude 153.5°E which put the center about 640 miles (1035 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 17 m.p.h. (28 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 961 mb.

Typhoon Koguma intensified to the equivalent of a major hurricane on Friday as it was completing an eyewall replacement cycle.  A new larger eye was forming at the center of Koguma’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

Even though Typhoon Koguma was completing an eyewall replacement cycle, the circulation around Koguma was still small for a typhoon over the Western North Pacific Ocean.  Winds to typhoon force extended out 45 miles (75 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6.  The Hurricane Size Index (HSI) is 16.2 and the Hurricane Wind Intensity Size Index (HWISI) is 36.8.  Typhoon Koguma is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo continued to weaken gradually far to the southeast of Japan.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Nolo was located at latitude 29.7°N and longitude 147.6°E which put the center about 635 miles (1025 km) southeast of Tokyo, Japan.  Nolo was moving toward the northwest at 13 m.p.h. (21 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 991 mb.

Koguma Strengthens to a Typhoon

Former Tropical Storm Koguma strengthened to a typhoon over the Western North Pacific Ocean east of the Northern Marianas on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Koguma was located at latitude 18.4°N and longitude 157.1°E which put the center about 810 miles (1310 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 14 m.p.h. (22 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 980 mb.

Former Tropical Storm Koguma strengthened to a typhoon on Thursday.  The inner end of a rainband wrapped around the southern side of the center of Koguma’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  Storms near the center of Koguma 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 Koguma was fairly symmetrical.  Winds to typhoon force extended out 30 miles (50 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.  Koguma could strengthen to the equivalent of a major hurricane during the weekend.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo was weakening gradually far to the southeast of Japan.

At 5:00 p.m. EDT on Thursday the center of Tropical Storm Nolo was located at latitude 28.1°N and longitude 150.6°E which put the center about 855 miles (1380 km) east-southeast of Tokyo, Japan.  Nolo was moving toward the west-northwest at 17 m.p.h. (28 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 991 mb.

Choi-wan Strengthens to Typhoon West of Northern Marianas

Former Tropical Storm Choi-wan strengthened to a typhoon over the Western North Pacific Ocean west of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Choi-wan was located at latitude 18.0°N and longitude 144.7°E which put the center about 80 miles (130 km) west of Alamagan.  Choi-wan was moving toward the north at 9 m.p.h. (15 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 981 mb.

A Typhoon Warning is in effect for Agrihan and Pagan.

A Tropical Storm Warning is in effect for Tinian, Saipan, and Alamagan.

A Typhoon Watch is in effect for Alamagan.

Former Tropical Storm Choi-wan strengthened to a typhoon on Friday.  The inner end of a rainband wrapped around the center of Typhoon Choi-wan.  Other bands of showers and thunderstorms were revolving around the center of Choi-wan’s circulation.  Storms near the center of Choi-wan 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 Choi-wan was asymmetrical.  Winds to typhoon force extended out 110 miles (175 km) in the southern half of Choi-wan’s circulation.  Winds to tropical storm force extended out 50 miles (80 km) in the northern half of Typhoon Choi-wan.  Winds to tropical storm force extended out 250 miles (400 km) in the southern side of Typhoon Choi-wan.  Winds to tropical storm force extended out 175 miles (280 km) in the northern side of Choi-wan’s circulation.

Typhoon Choi-wan will move through an environment that will be favorable for intensification during the next 24 hours.  Choi-wan Choi-wan 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 Choi-wan will intensify during the next 24 hours.  Choi-wan is likely to strengthen to the equivalent of a major hurricane during the weekend.

Tropical Storm Choi-wan will move around the western end of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Choi-wan toward the north during the next 24 hours.  On its anticipated track, Tropical Storm Choi-wan will move away from the Northern Marianas during the weekend.

Tropical Storm Choi-wan will bring strong winds and heavy rain to Alamagan, Agrihan, Pagan, and Anataham.  Heavy rain could cause floods in some locations. Choi-wan could also bring gusty winds and heavy rain to Tinian and Saipan.  Bands in the southern periphery of Typhoon Choi-wan could drop heavy rain over Guam and Rota.

Flood Watches are in effect for Guam, Rota, Tinian, and Saipan.