Tag Archives: Guam

Typhoon Bavi Intensifies to Equivalent of a Major Hurricane

Typhoon Bavi intensified to the equivalent of a major hurricane on Thursday night.  The threat posed by Bavi prompted the issuance of Typhoon Watches and Tropical Storm Watches for the Marianas.  At 5:00 a.m. EDT on Friday the center of Typhoon Bavi was located at latitude 12.9°N and longitude 153.8°E which put the center about 625 miles (1010 km) east of Guam.  Bavi was moving toward the west at 13 m.p.h. (21 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 955 mb.

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

Tropical Storm Watches are in effect for Alamagan, Pagan, and Agrihan.

A circular eye with a diameter of 21 miles (33 km) was at the center of Typhoon Bavi.  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 Bavi’s circulation.  Storms near the core of Bavi generated strong upper level divergence that pumped large quantities of mass away from typhoon.  The removal of large quantities of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Bavi was fairly symmetrical.  Winds to typhoon force extended out 50 miles (80 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Typhoon Bavi.

The Hurricane Intensity Index (HII) for Typhoon Bavi is 22.1.  The Hurricane Size Index (HSI) is 18.6 and the Hurricane Wind Intensity Size Index (HWISI) is 40.7.  Typhoon Bavi is similar in intensity to Hurricane Jeanne when Jeanne hit South Florida in 2004.  Bavi is not quite as large as Jeanne was.

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

Typhoon Bavi 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 Bavi toward the west during the next 24 hours.  On its anticipated track, Typhoon Bavi could reach the Marianas in less than 60 hours.

Typhoon Bavi will bring strong winds and heavy rain to the Marianas.  Bavi could be capable of causing catastrophic damage.  Heavy rain will cause flash floods in some locations.

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

Typhoon Bavi could cause a storm surge of up to 16 feet (5 meters) along the coast of the Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Maysak was bringing gusty winds and locally heavy rain to Hainan.  At 5:00 a.m. EDT on Friday the center of Tropical Storm Maysak was located at latitude 17.9°N and longitude 109.4°E which put the center about 25 miles (40 km) south of Sanya, China.  Maysak was moving toward the northwest at 6 m.p.h. (10 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 999 mb.

Bavi Strengthens to a Typhoon

Former Tropical Storm Bavi strengthened to a typhoon over the Western North Pacific Ocean east of the Marianas on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Bavi was located at latitude 12.7°N and longitude 156.1°E which put the center about 790 miles (1275 km) east of Guam.  Bavi was moving toward the west-northwest at 14 m.p.h. (22 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 982 mb.

Former Tropical Storm Bavi strengthened to a typhoon on Thursday.  The inner end of a rainband wrapped around the center of Bavi’s circulation.  A circular eye formed at the center of Typhoon Bavi.  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 Bavi’s circulation.  Storms near the center of Bavi generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Typhoon Bavi increased on Thursday as Bavi intensified.  Winds to typhoon force extended out 50 miles (80 km) from the center of Bavi’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) from the center of Typhoon Bavi.

Typhoon Bavi will more through an environment that will be very favorable for intensification during the next 24 hours.  Bavi 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 Bavi will intensify during the next 24 hours.  Bavi could intensify rapidly at times. Typhoon Bavi could strengthen to the equivalent of a major hurricane during the next 24 hours.

Typhoon Bavi 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 Bavi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Bavi could reach the Marianas in less than 72 hours.

Typhoon Bavi will bring strong winds and heavy rain to the Marianas.  Bavi could be capable of causing catastrophic damage.  Heavy rain will cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression 10W strengthened to Tropical Storm Maysak southeast of Hainan.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Maysak was located at latitude 17.6°N and longitude 110.2°E which put the center about 50 miles (80 km) southeast of Sanya, China.  Maysak 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 1002 mb.

Tropical Storm Bavi Intensifies

Tropical Storm Bavi was intensifying over the Western North Pacific Ocean east of the Marianas on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Bavi was located at latitude 11.2°N and longitude 159.7°E which put the center about 1050 miles (1690 km) east of Guam.  Bavi was moving toward the west-northwest at 15 m.p.h. (24 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 996 mb.

Former Tropical Depression 09W intensified on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Bavi.

The circulation around Tropical Storm Bavi exhibited much more organization on Wednesday evening.  The inner end of a rainband wrapped around the western side of the center of Bavi’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Tropical Storm Bavi.  Storms near the center of Bavi generated more upper level divergence that pumped mass away from the tropical storm.  The removal of more mass caused the surface pressure to decrease.

The distribution of wind speeds in Tropical Storm Bavi became more symmetrical on Wednesday.  Winds to tropical storm force extended out 80 miles (130 km) from the center of Bavi’s circulation.

Tropical Storm Bavi will more through an environment that will be very favorable for intensification during the next 24 hours.  Bavi 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.  Tropical Storm Bavi is likely to intensify to a typhoon during the next 24 hours.  Bavi could intensify rapidly at times.  Tropical Storm Bavi is likely to strengthen to the equivalent of a major hurricane by the weekend.

Tropical Storm Bavi 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 Bavi toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Bavi could reach the Marianas in less than four days.

Tropical Storm Bavi is likely to intensify to the equivalent of a major hurricane before it reaches the Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 10W formed over the South China Sea.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression 10W was located at latitude 17.7°N and longitude 112.6°E which put the center about 250 miles (400 km) east-southeast of Sanya, China.  The tropical depression was moving toward the west at 21 m.p.h. (33 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.

Tropical Depression 10W is forecast to strengthen to a tropical storm before it reaches Hainan.  It will bring strong winds and locally heavy rain to Hainan.  Heavy rain could cause flash floods in some locations.

Typhoon Mekkhala Weakens

Typhoon Mekkhala weakened on Tuesday as it moved toward the southern Ryukyu Islands.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Mekkhala was located at latitude 21.3°N and longitude 124.7°E which put the center about 235 miles (380 km) south of Miyakojima, Japan.  Mekkhala was moving toward the north 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 105 m.p.h. (165 km/h).  The minimum surface pressure was 974 mb.

Typhoon Mekkhala weakened on Tuesday.  An upper level ridge over China produced northeasterly winds that blew toward the top of Mekkhala’s circulation.  Those winds caused strong vertical wind shear.  The strong vertical wind shear caused Typhoon Mekkhala to weaken.

The northeasterly winds in the upper levels also blew the tops off of many of the thunderstorms in the northern half of Typhoon Mekkhala.  Thunderstorms were still occurring in bands in the southern half of Mekkhala’s circulation.  Bands in the northern half of Typhoon Mekkhala consisted primarily of showers and lower clouds.  Storms near the center of Mekkhala generated upper level divergence that pumped mass away to the south and west of 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 increased on Tuesday.

Even though Typhoon Mekkhala weakened on Tuesday, the size of Mekkhala’s circulation did not change much.  Winds to typhoon force extended out 65 miles (105 km) from the center of Typhoon Mekkhala.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Mekkhala’s circulation.

Typhoon Mekkhala will move through an environment that will be unfavorable for intensification during the next 24 hours.  Mekkhala will move over water where the Sea Surface Temperatures are near 28°C.  However, the upper level ridge over China will continue to cause strong vertical wind shear.  Typhoon Mekkhala will continue to weaken during the next 24 hours because of the strong vertical wind shear.

Typhoon Mekkhala will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Mekkhala toward the north during the next 24 hours.  On its anticipated track, Typhoon Mekkhala will reach the southern Ryukyu Islands in less than 24 hours.

Typhoon Mekkhala will bring strong winds and locally heavy rain to the southern Ryukyu Islands including Ishigakijima and Miyakojima.  Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Higos weakened to a tropical depression as it moved west of the Marianas.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Higos was located at latitude 15.4°N and longitude 141.3°E which put the center about 225 miles (360 km) west-northwest of Guam.  Higos was moving toward the west-northwest at 11 m.p.h. (17 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 1002 mb.

Tropical Depression Forms West of Guam

Tropical Depression 07W formed over the Western North Pacific Ocean west-southwest of Guam on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Depression 07W was located at latitude 13.1°N and longitude 142.5°E which put the center about 150 miles (240 km) west-southwest of Guam.  Tropical Depression 07W was moving toward the west-northwest at 17 m.p.h. (28 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 1005 mb.

A low pressure system over the Western North Pacific Ocean west-southwest of Guam strengthened on Thursday night and both the Japan Meteorological Agency and the U.S. Joint Typhoon Warning Center classified the system as a tropical depression.

The distribution of thunderstorms in Tropical Depression 07W was asymmetrical.  Thunderstorms were occurring in bands in the southern half of the tropical depression.  Bands in the northern half of Tropical Depression 07W consisted primarily of showers and lower clouds.  Storms near the center of circulation began to generate upper level divergence that pumped mass away to the west of the tropical depression.  The removal of mass caused the surface pressure to decrease.

Tropical Depression 07W will move through an environment mostly favorable for intensification during the next 24 hours.  The tropical depression 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 that is southwest of Japan.  The upper level ridge will produce northeasterly winds that will blow toward the top of the tropical depression.  Those winds will cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Tropical Depression 07W is likely to intensify to a tropical storm during the next 24 hours.  It could strengthen to a typhoon during the weekend.

Tropical Depression 07W will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer the tropical depression toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Depression 07W will move away from the Marianas.

Tropical Storm Hagupit Passes South of Guam

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

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

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.

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.