Tag Archives: 27W

Typhoon Mangkhut Strengthens Into Equivalent of Cat. 5 Hurricane

Typhoon Mangkhut strengthened into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Tuesday.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Mangkhut was located at latitude 13.7°N and longitude 138.0°E which put it about 290 miles (470 km) north of Yap.  Mangkhut was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 915 mb.

Typhoon Mangkhut is strong and well organized.  It has a symmetrical circulation with a circular eye at the center.  A ring of strong thunderstorms surround the eye and the strongest winds are occurring in the ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Typhoon Mangkhut.  Storms near the core were generating strong upper level divergence which was pumping large quantities of mass away from the typhoon in all directions.

Typhoon Mangkhut has a large circulation.  Winds to typhoon force extend out about 65 miles (105 km) from the center of circulation.  Winds to tropical storm force extend out about 210 miles (375 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Mangkhut is 35.0.  The Hurricane Size Index (HSI) is 22.1 and the Hurricane Wind Intensity Size Index (HWISI) is 57.1.  Typhoon Mangkhut is capable of causing extensive catastrophic damage.

Typhoon Mangkhut will be moving through an environment very favorable for powerful typhoons.  Mangkhut will be moving over water where the Sea Surface Temperature is near 30°C.  It will move through an area were the upper level winds are weak and there will be little vertical wind shear.  Typhoon Mangkhut could maintain its intensity for several more days unless eyewall replacement cycles cause fluctuations in the wind speed.

Typhoon Mangkhut is moving south a ridge of high pressure over the Western North Pacific Ocean.  The ridge will steer Mangkhut in a general west-northwesterly direction during the next few days.  On its anticipated track Typhoon Mangkhut could approach northern Luzon in about three days.  Mangkhut could be near Hong Kong in about five days.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Barijat was moving southeast of Hong Kong.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Barijat was located at latitude 20.5°N and longitude 116.5°E which put it about 215 miles (345 km) southeast of Hong Kong.  Barijat was moving toward the west-southwest 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 1000 mb.

Tropical Storm Saola Speeding Toward Tokyo

Tropical Storm Saola sped toward Tokyo, Japan on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Saola was located at latitude 32.4°N and longitude 134.4°E which put it about 370 miles (595 km) west-southwest of Tokyo.  Saola was moving toward the northeast at 24 m.p.h. (39 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 979 mb.

Tropical Storm Saola was weakening and making a transition to an extratropical cyclone.  A primary band of showers and thunderstorms wrapped around the eastern side of the circulation.  There were other thinner bands of showers revolving around the core of the circulation.  Strong westerly winds in the upper levels were causing significant vertical wind shear which was tilting the upper part of the circulation toward the northeast.  Cooler drier air appeared to be flowing toward the western part of the circulation.

Westerly winds in the middle latitudes were steering Tropical Storm Saola quickly toward the northeast.  The center of Saola will pass south of Shikoku.  On its anticipated track the center of Tropical Storm Saola will pass near Tokyo in about 12 hours.  Tropical Storm Saola will bring gusty winds and locally heavy rain to Shikoku and central Honshu.  The heavy rain could cause flash floods in some locations.

Typhoon Saola Near Okinawa

The core of Typhoon Saola moved near Okinawa on Friday night.  At 11:00 p.m. EDT on Friday the center of Typhoon Saola was near latitude 26.2°N and longitude 128.2°E which put it about 70 miles (110 km) south of Okinawa.  Saola was moving toward the north at 14 m.p.h. (22 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 979 mb.

The circulation of Typhoon Saola became more well organized on Friday.   The primary rainband wrapped most of the way around the center of circulation.  A large eye was surrounded by a broken ring of showers and thunderstorms.  Low clouds and showers were scattered throughout the large eye.  Several other bands of showers and storms were revolving around the core of Typhoon Saola.  The rainbands were weaker on the northwestern side of Typhoon Saola and there appeared to be cooler, drier air on that side of the typhoon.  Winds to typhoon force extended out about 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.

Typhoon Saola could be near its maximum intensity.  Saola will move over water where the Sea Surface Temperature is near 29°C.  However Typhoon Saola is near the upper level westerly winds in the middle latitudes and the vertical wind shear will increase on Saturday.  Typhoon Saola could strengthen a little more during the next six to twelve hours, but it will start to weaken when the vertical wind shear increases.

Typhoon Saola is moving around the western end of a ridge which is steering Saola toward the north.  When Typhoon Saola reaches the westerly winds of the middle latitudes, those winds will turn Saola toward the east-northeast.  On its anticipated track Typhoon Saola will bring strong winds and heavy rain to Okinawa and the Ryukyu Islands.  The center of Typhoon Saola will be near southern Kyushu in about 12 hours and the center could pass near Tokyo in about 24 hours.

Tropical Storm Saola Strengthens, Moves Toward Okinawa

Tropical Storm strengthened on Thursday as it moved closer to Okinawa.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Saola was located at latitude 22.2°N and longitude 129.4°E which put it about 350 miles (570 km) south-southeast of Okinawa.  Saola was moving toward the north-northwest at 17 m.p.h. (27 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 987 mb.

The circulation of Tropical Storm Saola exhibited more organization in recent hours.  For much of the past several days many of the showers and thunderstorms were in a single primary rainband that wrapped around the outer part of the circulation.  There were few showers or storms near and to the north of the center of circulation.  A broken ring of showers and thunderstorms began to develop around the center during the past few hours.  The ring could represent the initial formation of an eyewall.  Additional bands of showers and thunderstorms also began to form outside the core of Tropical Storm Saola.

Tropical Storm Saola will be moving through an environment that will be favorable for intensification during the next 24 hours.  Saola will move over water where the Sea Surface Temperature is near 29°C.  The winds will be similar in all levels of the atmosphere and there will be little vertical wind shear.  Tropical Storm Saola will intensify on Friday and it could become a typhoon.  After about 24 hours Tropical Storm Saola will reach the upper level westerly winds in the middle latitudes and the vertical wind shear will increase.  More wind shear will start to weaken Saola.

Tropical Storm Saola was moving the western end of a ridge which is steering the tropical storm toward the north-northwest and that general motion is expected to continue for about another 24 hours.  On its anticipated track Tropical Storm Saola will approach Okinawa in about 24 hours.  When Saola nears Okinawa, it will encounter the westerly winds in the middle latitudes.  Those winds will turn Saola toward the northeast.  Tropical Storm Saola will bring gusty winds and locally heavy rain to Okinawa and the Ryukyu Islands.

Tropical Storm Saola Develops West of Guam

Tropical Storm Saola developed west of Guam on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Saola was located at latitude 14.8°N and longitude 134.8°E which put it about 375 miles (605 km) northwest of Yap.  Saola was moving toward the west-northwest 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 997 mb.

The core of the circulation of Tropical Storm Saola became more well organized on Tuesday.  The center of circulation strengthened and more thunderstorms developed close to the center  Bands of showers and thunderstorms formed outside the core of Tropical Storm Saola.  Many of the showers and storms formed southwest of the center.  There were fewer showers and storms northeast of the center.  The storms near the core of Saola began to produce upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Saola will move through an environment that will be somewhat favorable for intensification.  Saola will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of Tropical Storm Saola is producing easterly winds which are blowing toward the top of the circulation.  Those winds are causing moderate vertical wind shear which is inhibiting the intensification of Tropical Storm Saola.  The upper level winds are forecast to weaken which would cause the wind shear to decrease.  The decreased wind shear should allow Tropical Storm Saola to intensify during the next several days and it could eventually strengthen into a typhoon.

The upper level ridge has been steering Tropical Storm Saola toward the west-northwest.  An upper level trough east of Asia is forecast to weaken the ridge.  When the ridge weakens,Tropical Storm Saola will turn more the north.  On its anticipated track Tropical Storm Saola will remain east of the Philippines and Taiwan.  Tropical Storm Saola could approach Okinawa in about 72 hours.  Saola could be a typhoon when it approaches Okinawa.

Typhoon Lan Brings Wind and Rain to Japan

Typhoon Lan brought wind and rain to parts of Japan on Sunday.  At 5:00 p.m. EDT on Sunday the center of Typhoon Lan was located at latitude 35.2°N and longitude 139.1°E which put it about 50 miles southwest of Tokyo, Japan.  Lan was moving toward the northeast at 37 m.p.h. (60 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 960 mb.

Typhoon Lan weakened significantly before it reached Japan.  Lan moved over cooler water south of Japan.  Strong upper level westerly winds caused strong vertical wind shear.  The circulation of Lan pulled drier air into the western half of the circulation.  The combination of cooler water, strong shear and drier air caused the significant weakening.  In addition the shear was strong enough to push the heavier rain to the northeast of the center of Typhoon Lan.

Lan was still a typhoon when it made landfall in Honshu despite the unfavorable environment.  A weather station at the Tokyo International Airport reported a wind speed of 56 m.p.h. (90 km/h).  Some areas in eastern Honshu experienced periods of heavy rain and gusty winds.  The drier air will limit the rainfall after the center of the typhoon passes a given location.

The strong westerly winds will steer Typhoon Lan rapidly toward the northeast.  Lan will move east of Honshu in a few hours.  The strong vertical wind shear and cooler, drier air will cause Typhoon Lan to transition to a strong extratropical cyclone east of Japan.

While Typhoon Lan races across eastern Japan, Tropical Depression 27W organized southeast of Guam.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression 27W was located at latitude 9.3°N and longitude 147.4°E which put it about 360 miles (580 km) southeast of Guam.  It was moving toward 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 gust to 45 m.p.h.  The minimum surface pressure was 1004 mb.

Tropical Depression 27W will move through an environment that will be somewhat favorable for development during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge centered northeast of the Marianas is producing easterly winds which are blowing over the top of the depression.  Those winds are causing moderate vertical wind shear.  The shear is inhibiting the organization of the circulation and it is slowing the development of the depression.  The shear is forecast to decrease during the next several days and the depression could strengthen into a tropical storm if a distinct low level center forms.

Tropical Depression 27W is near the southwestern end of the ridge to its northeast.  The ridge is currently steering the depression toward the west.  It is forecast to move around the end of the ridge and turn more toward the north during the next few days.  On its anticipated track the depression could be near Guam in about 24 hours.  It could be a tropical storm at that time.

Tropical Storm Ma-On Forms East of the Northern Marianas

Tropical Depression 27W intensified into Tropical Storm Ma-On east of the Northern Marianas on Thursday.  At 10:00 a.m. EDT on Thursday the center of Tropical Storm Ma-On was located at latitude 17.7°N and longitude 153.7°E which put it about 405 miles (655 km) south-southeast of Minami Tori Shima.  Ma-On was moving toward the west at 15 m.p.h. (24 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.

More thunderstorms developed near the center of a system originally designated Tropical Depression 27W and the Japan Meteorological Agency named it Tropical Storm Ma-On on Thursday.  Although many of the thunderstorms are still developing east of the center of circulation, a few stronger thunderstorms are forming around the center.  The thunderstorms around the center are beginning to generate upper level divergence which is pumping out mass.  Some additional rainbands appear to be forming in the eastern half of the circulation.

Tropical Storm Ma-On is moving through an environment that is favorable for intensification.  Ma-On is moving over water where the Sea Surface Temperature is near 30°C.  Ma-On is moving under the western end of an upper level ridge.  The upper level winds in that part of the ridge are not too strong and the ridge may be enhancing upper level divergence.  Tropical Storm Ma-On could intensify during the next day or so.  When Ma-On gets farther west, it will approach an upper level trough moving off of Asia.  There are stronger southwesterly winds on the eastern side of the trough and the vertical wind shear will increase at that time.

Tropical Storm Ma-On is moving along the southwestern end of a subtropical high pressure system.  The subtropical high is expected to steer Ma-On in a general west-northwesterly direction during the next two or three days.  On its anticipated track Tropical Storm Ma-On could approach the northernmost Marianas in about 36 hours.  It could bring gusty winds and locally heavy rain.

In-Fa Weakens to a Tropical Storm on Its Way to Iwo To

In-Fa weakened below typhoon intensity on Tuesday as it moved toward Iwo To.  At 10:00 p.m. EST on Tuesday the center of Tropical Storm In-Fa was located at latitude 20.1°N and longitude 135.3°E which put it about 540 miles (870 km) southwest of Iwo To.  In-Fa was moving toward the northeast at 10 m.p.h. (16 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 994 mb.

A large upper level trough that extends south of Japan is producing strong southwesterly winds over the top of Tropical Storm In-Fa.  Those winds are causing strong vertical wind shear which is tilting the upper portion of the circulation of the tropical storm toward the northeast.  The stronger thunderstorms are all located northeast of the center of In-Fa.  It also appears drier air is wrapping around the southwestern part of the circulation.  The strong vertical wind shear will continue to weaken Tropical Storm In-Fa.  As it moves into a cooler environment In-Fa will gradually make a transition to an extratropical cyclone during the next 48 hours.

The upper level trough will continue to steer Tropical Storm In-Fa toward the northeast while it makes the transition to an extratropical cyclone.  On its anticipated track In-Fa could bring tropical storm force winds to Iwo To in 24 to 36 hours.

Typhoon In-Fa Turns Toward Iwo To

Typhoon In-fa turned northeast and started to move toward Iwo To late on Monday.  At 10:00 p.m. EST on Monday the center of Typhoon In-Fa was located at latitude 19.0°N and longitude 132.6°E which put it about 695 miles (1120 km) southwest of Iwo To.  In-Fa was moving toward the northeast at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 956 mb.

Although In-Fa may be beginning to respond to increased vertical wind shear, it remains a well organized typhoon.  There are signs that a cloud filled eye still exists at the core of In-Fa.  The eye is surround by a ring of strong thunderstorms.  The outer portion of In-Fa’s circulation is becoming more asymmetrical, which is probably the result of increased wind shear.  Most of the thunderstorms outside the core are north and east of the center of circulation.  There are few thunderstorms in the southwestern part of In-Fa.

Typhoon In-Fa is currently over water where the Sea Surface Temperature (SST) is near 28°C.  In-Fa will move over increasingly cooler SSTs as it moves northeast.  The strength of the upper level southwesterly winds will increase as In-Fa moves northeast.  The combination of cooler SSTs and more vertical wind shear will cause Typhoon In-Fa to weaken during the next several days.  It could weaken to a tropical storm by Wednesday.

An upper level trough is steering Typhoon In-Fa toward the northeast and that general motion is expected to continue during the next 48 hours.  In-Fa could start to move faster as the upper level winds increase.  In-Fa could be near Iwo To in about 48 hours.

Typhoon In-Fa Passes North of Yap

The center of Typhoon In-Fa passed north of Yap on Saturday.  At 10:00 p.m. EST on Saturday the center of Typhoon In-Fa was located at latitude 13.7°N and longitude 136.0°E which put it about 285 miles (465 km) north-northwest of Yap.  In-Fa was moving toward the west-northwest at 19 m.p.h. (31 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 944 mb.

The structure of Typhoon In-Fa deteriorated slightly on Saturday, but it remains the equivalent of a major hurricane.  Fewer thunderstorms formed in the northwestern quadrant of the circulation and there are indications that a gap may have opened on the northwestern side of the eyewall.  It is possible that some drier air could have been pulled into that part of the circulation.  However, an eye may still exist at the center of circulation and there are multiple bands around the eastern and southern sides of the typhoon.

Typhoon In-Fa is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds over the top of the circulation are light and there is not much vertical wind shear over the core of the typhoon.  Typhoon In-Fa could maintain its intensity or weaken slowly on Sunday.  When it moves farther north, it will encounter stronger southwesterly winds which will increase the vertical wind shear.  When the wind shear increases, the rate of weakening will increase.

A subtropical ridge is steering Typhoon In-Fa toward the west-northwest and that general motion is expected to continue for another day or so.  In-Fa could reach the western end of the ridge and turn northward on Monday.  In 36 to 48 hours the southwesterly upper level winds will start to push the typhoon toward the northeast.  On its anticipated track Typhoon In-Fa could be near Iwo To in about four days.