Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Storm Hagupit Passes North of Palau

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Tropical Storm Hagupit passed north of Palau on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Hagupit was located at latitude 10.4°N and longitude 132.9°E which put the center about 220 miles (355 km) north-northwest of Koror, Palau.  Hagupit was moving toward the northwest at 10 m.p.h. (16 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 1004 mb.

Tropical Storm Hagupit maintained its intensity while it passed north of Palau on Saturday.  Even though Tropical Storm Hagupit maintained its maximum wind speed, some of the thunderstorms in Hagupit’s circulation dissipated.  Thunderstorms were still occurring in bands in the eastern side of Tropical Storm Hagupit.  Bands in the western side of Hagupit’s circulation consisted primarily of showers and lower clouds.  Thunderstorms near the center of Hagupit generated less upper level divergence that pumped less mass away from the tropical storm.  The removal of less mass caused the surface pressure to increase.

Tropical Storm Hagupit will move into an environment that will be unfavorable for intensification during the next 24 hours.  Hagupit will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern end of an upper level trough that is south of Japan.  The upper level trough will produce westerly winds that will blow toward the top of Hagupit’s circulation.  Those winds will cause more vertical wind shear.  Tropical Storm Hagupit is likely to weaken to a tropical depression on Sunday.

Tropical Storm Hagupit will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.   The high pressure system will steer Hagupit toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Hagupit will move farther away from Palau.

Tropical Storm Hagupit Produces Gusty Winds on Yap

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Tropical Storm Hagupit produced gusty winds on Yap on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Hagupit was located at latitude 8.8°N and longitude 136.6°E which put the center about 90 miles (145 km) southwest of Yap.  Hagupit was moving toward the west at 10 m.p.h. (16 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.

Even though the center of Tropical Storm Hagupit passed south of Yap on Friday, Hagupit still produced gusty winds on Yap.  A weather station at the Yap International Airport (PTYA) reported a wind gust of 40 m.p.h. (65 km/h) on Friday.

Tropical Storm Hagupit weakened a little on Friday.  Some of the thunderstorms in bands in the western half of Hagupit’s circulation dissipated.  Numerous thunderstorms were still occurring in bands in the eastern side of Tropical Storm Hagupit.  Thunderstorms near the center of Hagupit generated a little less upper level divergence that pumped less mass away from the tropical storm.  The removal of less mass caused the surface pressure to increase.

The strongest winds were occurring in the northeastern part of Tropical Storm Hagupit.  Winds to tropical storm force extended out 85 miles (135 km) in the northeastern quadrant of Hagupit’s circulation.  The winds in the other parts of Tropical Storm Hagupit were blowing at less than tropical storm force.

Tropical Storm Hagupit will move into an environment that will become more unfavorable for intensification during the next 24 hours.  Hagupit will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern end of an upper level trough that is south of Japan.  The upper level trough will produce westerly winds that will blow toward the top of Hagupit’s circulation.  Those winds will cause the vertical wind shear to increase.  Tropical Storm Hagupit will weaken when the vertical wind shear increases.

Tropical Storm Hagupit will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Hagupit toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Hagupit will move away from Yap.  Hagupit will pass north of Palau during the weekend.

Tropical Storm Hagupit will continue to produce gusty winds on Yap during the next few hours until Hagupit moves farther away,  Hagupit will also bring passing showers and thunderstorms to Yap.  Locally heavy rainfall could cause flash floods in some locations.

Tropical Storm Hagupit Approaches Yap

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Tropical Storm Hagupit was approaching Yap on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Hagupit was located at latitude 8.6°N and longitude 139.5°E which put the center about 145 miles (230 km) east-southeast of Yap.  Hagupit was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (80 km/h).  The minimum surface pressure was 999 mb.

Tropical Storm Hagupit was intensifying as it approached Yap on Thursday night.  More thunderstorms were developing near the center of Hagupit’s circulation.  Bands of showers and thunderstorms were revolving around the center of Tropical Storm Hagupit.  Storms near the center of Hagupit generated more upper level divergence that pumped mass away from the tropical storm.  The removal of more mass caused the surface pressure to decrease.

Even though Tropical Storm Hagupit was intensifying, the distribution of wind speeds continued to be asymmetrical.  Winds to tropical storm force extended out 110 miles (175 km) in the northern side of Hagupit’s circulation.  The winds in the southern half of Tropical Storm Hagupit were blowing at less that tropical storm force.

Tropical Storm Hagupit will move through an environment favorable for intensification during the next 24 hours.  Hagupit 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 the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Hagupit’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Storm Hagupit will intensify during the next 24 hours.

Tropical Storm Hagupit will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Hagupit toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Hagupit will reach Yap within 12 hours.

Tropical Storm Hagupit will bring strong winds and locally heavy rain to Yap.  Heavy rain could cause flash floods in some locations.  Tropical Storm Hagupit could cause a storm surge of up to 6 feet (1.8 meters) along the coast of Yap.

Tropical Storm Hagupit Passes South of Guam

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Tropical Storm Hagupit passed well to the south of Guam on Wednesday night.  At 5:00 a.m. EDT on Thursday the center of Tropical Storm Hagupit was located at latitude 7.2°N and longitude 142.5°E which put the center about 355 miles (575 km) east-southeast of Yap.  Hagupit was moving toward the west 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 1001 mb.

Tropical Storm Hagupit exhibited a little more organization on Thursday morning.  Thunderstorms were once again forming in bands in all parts of Hagupit’s circulation.  Thunderstorms near the center of Hagupit generated more upper level divergence that pumped mass away from the tropical storm.  The removal of more mass caused the surface pressure to decrease slightly.

Even though Tropical Storm Hagupit looked more organized on satellite images, the distribution of wind speeds continued to be asymmetrical.  Winds to tropical storm force extended out 115 miles (185 km) in the northern side of Hagupit’s circulation.  The winds in the southern half of Tropical Storm Hagupit were blowing at less that tropical storm force.

Tropical Storm Hagupit will move through an environment favorable for intensification during the next 24 hours.  Hagupit 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 the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Hagupit’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Storm Hagupit will intensify slowly during the next 24 hours.

Tropical Storm Hagupit will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Hagupit toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Hagupit will approach Yap in 24 hours.

Tropical storm Hagupit will bring strong winds and locally heavy rain to Yap.  Heavy rain could cause flash floods in some locations.

Depression Strengthens to Tropical Storm Hagupit

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Former Tropical Depression 05W strengthened to Tropical Storm Hagupit over the Western North Pacific Ocean south of the Marianas on Tuesday night.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Hagupit was located at latitude 7.4°N and longitude 146.5°E which put the center about 435 miles (705 km) south-southeast of Guam.  Hagupit was moving toward the west at 7 m.p.h. (11 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.

Former Tropical Depression 05W strengthened on Tuesday night and the Japan Meteorological Agency designated the system as Tropical Storm Hagupit.

Thunderstorms continued to develop near the center of Tropical Storm Hagupit.  However, the distribution of thunderstorms around the rest of Hagupit’s circulation became a little more asymmetrical during the past 12 hours.  Thunderstorms were still occurring in bands in the eastern side of Tropical Storm Hagupit.  Bands in the western side of Hagupit’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Hagupit generated some upper level divergence that pumped mass away from the tropical storm.  The removal of mass in the upper levels was nearly matched by the inflow of mass in the lower levels of the atmosphere.  So, the surface pressure was not changing much.

The distribution of wind speeds in Tropical Storm Hagupit was also asymmetrical.  Winds to tropical storm force extended out 100 miles (160 km) in the northeastern quadrant of Hagupit’s circulation.  The winds in the other parts of Tropical Storm Hagupit were blowing at less than tropical storm force.

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

Tropical Storm Hagupit will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Hagupit toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Hagupit will pass south of Guam.  Hagupit could approach Yap in 48 hours.  Hagupit will likely be a tropical storm when it approaches Yap.

Tropical Depression 05W Forms Southeast of the Marianas

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Tropical Depression 05W formed over the Western North Pacific Ocean southeast of the Marianas on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Depression 05W was located at latitude 8.4°N and longitude 147.8°E which put the center about 100 miles (160 km) north-northwest of Puluwat.  Tropical Depression 05W was moving toward the west at 8 m.p.h. (13 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 1003 mb.

A low pressure system over the Western North Pacific Ocean southeast of the Marianas strengthened on Tuesday.  Both the Japan Meteorological Agency and the U.S. Joint Typhoon Warning Center designated the system as a tropical depression.

More thunderstorms formed near the center of Tropical Depression 05W on Tuesday afternoon.  More thunderstorms also developed in bands revolving around the center of the tropical depression.  Storms near the center of circulation started to generate upper level divergence that pumped mass away from the tropical depression.  The removal of mass caused the surface pressure to decrease.

Tropical Depression 05W will move through an environment favorable for intensification during the next 24 hours.  The tropical depression 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 the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of the tropical depression.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Depression 05W will intensify to a tropical storm during the next 24 hours.  It could strengthen to a typhoon later this week.

Tropical Depression 05W will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer the tropical depression toward the west during the next 24 hours.  On its anticipated track, Tropical Depression 05W will pass south of Guam.  The tropical depression could approach Yap in 36 hours.  It will likely be a tropical storm when it approaches Yap.

Sinlaku Weakens to a Tropical Storm

Former Typhoon Sinlaku weakened to a tropical storm on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Sinlaku was located at latitude 25.8°N and longitude 149.2°E which put the center about 450 miles (730 km) east of Iwo To.  Sinlaku was moving toward the northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 983 mb.

Former Typhoon Sinlaku weakened to a tropical storm as it moved over cooler water on Saturday.  Many of the remaining thunderstorms in Tropical Storm Sinlaku dissipated on Saturday.  There were still some thunderstorms in bands in the eastern side of Sinlaku’s circulation.  The bands in the other parts of Tropical Storm Sinlaku consisted primarily of showers and lower clouds.  There was very little upper level divergence from Tropical Storm Sinlaku.  The convergence of mass in the lower levels of the atmosphere caused the surface pressure to continue to increase.

The circulation around Tropical Storm Sinlaku was still large.  Winds to tropical storm force extended out 250 miles (400 km) from the center of Sinlaku’s circulation.

Tropical Storm Sinlaku will move through an environment that will be unfavorable for intensification during the next 24 hours . Sinlaku will move over water where the Sea Surface Temperatures are near 23°C.  It will move under the southeastern part of an upper level trough that is southeast of Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Sinlaku’s circulation.  Those winds will cause moderate vertical wind shear.  Sinlaku will also continue to pull drier air into its circulation.  The drier air will continue to to inhibit the development of new thunderstorms in the rainbands revolving around the center of Sinlaku’s circulation.  The cooler Sea Surface Temperatures, moderate vertical wind shear and drier air will cause Tropical Storm Sinlaku to continue to weaken during the next 24 hours.

Tropical Storm Sinlaku will move around the northwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northeast during the next 24 hours.  On its anticipated track, Tropical Storm Sinlaku will continue to move away from Iwo To.

Typhoon Sinlaku Moves Away from the Marianas

Typhoon Sinlaku started to move away from the Marianas on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Sinlaku was located at latitude 21.2°N and longitude 146.4°E which put the center about 180 miles (290 km) north-northeast of Agrihan.  Sinlaku was moving toward the northeast at 7 m.p.h. (11 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 974 mb.

Typhoon Sinlaku continued to weaken as it moved away from the Marianas on Friday.  An eye was no longer visible at the center of Sinlaku’s circulation.  Thunderstorms were still occurring near the center of Typhoon Sinlaku.  Thunderstorms were also occurring in bands in the eastern and southern parts of Sinlaku’s circulation.  Bands in the western and northern parts of Typhoon Sinlaku consisted primarily of showers and lower clouds.  Storms near the center of Sinlaku still generated some upper level divergence that pumped mass away from the typhoon.  However, the removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So the surface pressure continued to increase.

The circulation around Typhoon Sinlaku was still large.  Winds to typhoon force extended out 65 miles (105 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 270 miles (435 km) from the center of Typhoon Sinlaku.

Typhoon Sinlaku will move through an environment that will be unfavorable for intensification during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 25°C.  It will move under the southeastern part of an upper level trough that is southeast of Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Sinlalu’s circulation.  Those winds will cause the moderate vertical wind shear.  Sinlaku also continue to pull drier air into its circulation.  The drier air will continue to to inhibit the development of new thunderstorms in the rainbands revolving around the center of Sinlaku’s circulation.  The cooler Sea Surface Temperatures, more vertical wind shear and drier air will cause Typhoon Sinlaku to continue to weaken during the next 24 hours.

Typhoon Sinlaku will move around the northwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northeast during the next 24 hours.  On its anticipated track, will continue to move away from the Marianas.

Typhoon Sinlaku Still Bringing Wind and Rain to Northern Marianas

Typhoon Sinlaku was still bringing wind and rain to the Northern Marianas on Thursday.  At 5:00 a.m. EDT on Thursday the center of Typhoon Sinlaku was located at latitude 18.0°N and longitude 144.6°E which put the center about 90 miles (145 km) west of Alamagan.   Sinlaku was moving toward the north at 7 m.p.h. (11 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 953 mb.

Typhoon Warnings remain in effect for Rota, Tinian, Saipan, Pagan, Alamagan, and Agrihan.

Typhoon Sinlaku was weakening gradually as it moved just to the west of the Northern Marianas.  The circulation around Sinlaku was pulling drier air into the typhoon.  There were fewer clouds in the regions between the rainbands.  Typhoon Sinlaku also appeared to be in the going through another eyewall replacement cycle.

The circulation around Typhoon Sinlaku was still well organized even though Sinlaku was weakening.  A circular eye with a diameter of 35 miles (55 km) was still visible at the center of Sinlaku’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Sinlaku.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was less than the convergence of mass in the lower levels.  So, the surface pressure was continuing to increase gradually.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 90 miles (145 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 290 miles (470 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 20.6.  The Hurricane Size Index (HSI) is 32.7 and the Hurricane Wind Intensity Size Index (HWISI) is 53.2.  Typhoon Sinlaku is similar in intensity to Hurricane Irma when Irma hit Southwest Florida in 2017.  Sinlaku is bigger than Irma was.

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the north-northeast during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will move over the northernmost islands in the Northern Marianas during the nest 24 hours.  Sinlaku will start to move away from the Marianas on Friday.

Typhoon Sinlaku will move through an environment that will become more unfavorable for a strong typhoon during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the southeastern part of an upper level trough that is southeast of Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Sinlalu’s circulation.  Those winds will cause the vertical wind shear to increase.  Typhoon Sinlaku will also continue to pull drier air into its circulation.  The drier air will continue to to inhibit the development of new thunderstorms in the rainbands revolving around the center of Sinlaku’s circulation.  The cooler Sea Surface Temperatures, more vertical wind shear and drier air will cause Typhoon Sinlaku to continue to weaken during the next 24 hours.

Typhoon Sinlaku will continue to bring strong winds and heavy rain to the Northern Marianas during the next 24 hours.  Heavy rain is likely to cause flash floods in some locations.

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

Typhoon Sinlaku could also cause a storm surge of up to 10 feet (3 meters).

Typhoon Sinlaku Continues to Bring Wind and Rain to Northern Marianas

Typhoon Sinlaku continued to bring strong winds and heavy rain to the Northern Marianas on Wednesday.  At 5:00 a.m. EDT on Wednesday the center of Typhoon Sinlaku was located at latitude 16.2°N and longitude 144.8°E which put the center about 80 miles (130 km) northwest of Saipan.  Sinlaku was moving toward the northwest at 6 m.p.h. (10 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 944 mb.

Typhoon Warnings remain in effect for Rota, Tinian, Saipan, Pagan, Alamagan, and Agrihan.

A Tropical Storm Warning remains in effect for Guam.

A Typhoon Watch also remains in effect for Guam.

Typhoon Sinlaku completed an eyewall replacement cycle on Wednesday.  A circular eye with a diameter of 35 miles (55 km) was present at the  center of Sinlaku’s circulation.  Bands of showers and thunderstorms were revolving around the core of Typhoon Sinlaku.  Storms near the core of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was less than the convergence of mass in the lower levels.  So, the surface pressure was continuing to increase gradually.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 75 miles (120 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 275 miles (445 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 23.6.  The Hurricane Size Index (HSI) is 28.3 and the Hurricane Wind Intensity Size Index (HWISI) is 51.9.  Typhoon Sinlaku is similar in size and intensity to Hurricane Wilma when Wilma hit South Florida in 2005.

A weather station at the Guam International Airport recently reported a sustained wind speed of 28 m.p.h. (45 km/h) and a wind gust of 45 m.p.h. (73 km/h).  There were no recent reports from weather stations on Rota, Tinian, or Saipan.

Typhoon Sinlaku was moving slowly west of the Northern Marianas.  The slow movement was prolonging the period destructive wind and rain in Tinian and Saipan.  Sinlaku was capable of causing major damage.  Prolonged heavy rain is likely to cause flash floods.

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

Typhoon Sinlaku could cause a storm surge of up to 10 feet (3 meters).

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the north-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will move very slowly away from Tinian and Saipan.  Sinlaku will move parallel of the Northern Marianas on Wednesday.

Typhoon Sinlaku will move through an environment that will be marginally favorable for a strong typhoon during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the middle of an upper level ridge that is over the Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will move into a region where the air is drier.  The drier air is likely to inhibit the development of thunderstorms in the northern and western parts of Sinlaku’s circulation.  Typhoon Sinlaku is likely to continue to weaken gradually during the next 24 hours because of the recently completed eyewall replacement cycle and the drier air.