Monthly Archives: October 2015

Typhoon Koppu Still Affecting Northern Luzon

The center of Typhoon Koppu moved across northern Luzon on Sunday and it is still affecting that region.  At 11:00 p.m. EDT on Sunday the center of Typhoon Koppu was located at latitude 17.5°N and longitude 120.3°E which put it about 200 miles (320 km) north-northwest of Manila, Philippines and just west of the coast of northwestern Luzon.  Koppu was moving toward the north-northeast at 5 m.p.h. (8 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. (170 km/h).  The minimum surface pressure was 968 mb.

Passage over northern Luzon weakened Typhoon Koppu and its structure is asymmetrical.  Most of the stronger thunderstorms are located in the western half of the circulation.  Much of the eastern half of the circulation is still over Luzon and there are few thunderstorms there.  The center of circulation is just west of Luzon.  Since it is back over water, the core of the typhoon could start to reorganize.  Intensification will be limited because of the large proportion of the circulation which is over land.

Koppu is near the western end of a subtropical ridge, which is causing the typhoon to move slowly northward.  That motion could continue for another 24 to 36 hours.  Eventually the ridge is expected to strengthen and push Typhoon Koppu northward at a faster speed.  Typhoon Koppu will continue to bring heavy rain to parts of northern Luzon for another day or two.

Strong Typhoon Champi Intensifies South of Iwo To

Typhoon Champi intensified rapidly on Sunday and it reached the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  At 5:00 p.m. EDT on Sunday the center of Typhoon Champi was located at latitude 20.3°N and longitude 140.3°E which put it about 325 miles (525 km) south-southwest of Iwo To.  Champi was moving toward the north-northeast at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 924 mb.

The circulation of Typhoon Champi is very well organized.  It has a well defined eye and there could be a rainband wrapping around the center to create concentric eyewalls.  Multiple spiral bands are revolving around the center of circulation.  Winds to typhoon force extend out 40 miles (65 km) from the center.  Well developed upper level divergence is pumping out mass in all directions.

Typhoon Champi is moving over water where the Sea Surface Temperature is near 29°C.  The winds in the upper levels are relatively light and there is not much vertical wind shear.  Champi will remain in a favorable environment for another 24 to 48 hours.  Eyewall replacement cycles could cause fluctuations in intensity during that period.  When it moves north of latitude 25°N, Champi will encounter the upper level westerly winds in the middle latitudes which will cause significant vertical wind shear.  Champi will weaken as the wind shear increases.

Champi is moving slowly northward as it curves around the western end of a subtropical ridge.  It will continue to move northward for another day or two.  When it begins to be affected by the upper level westerly winds, Champi will accelerate toward the northeast.  On its anticipated track Typhoon Champi will approach Iwo To in 48 to 60 hours.  Champi will be a large, strong typhoon at that time.

Olaf Becomes a Hurricane Between Baja and Hawaii

The core of the circulation of Olaf consolidated on Sunday and the National Hurricane Center upgraded it to a hurricane.  At 11:00 a.m. EDT on Sunday the center of Hurricane Olaf was located at latitude 9.5°N and longitude 133.2°W which put it about 1620 miles (2610 km) east-southeast of Hilo, Hawaii.  Olaf was moving toward the west at 12 m.p.h. (19 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 989 mb.

The circulation of Hurricane Olaf consists of a small core of thunderstorms around the center of circulation and a primary rainband that spirals around the western and southern sides of the hurricane.  The core of thunderstorms is producing some upper level divergence, but upper level winds are inhibiting the outflow on the western side of the center.

Hurricane Olaf is moving over water where the Sea Surface Temperature is near 30°C and there is plenty of energy in the upper ocean to support intensification.  However, an upper level trough north of Olaf is producing westerly winds which are blowing over the top of the hurricane.  The upper level winds are blocking upper level outflow on the western side of Olaf and the vertical wind shear is inhibiting the intensification of Olaf.  If the wind shear decreases, then further intensification will be possible.

A subtropical ridge is steering Hurricane Olaf toward the west and that general motion is expected to continue for another day or two.  When Olaf reaches the western end of the ridge, it will start to turn more toward the north.

Dangerous Typhoon Koppu Making Landfall in Northern Luzon

Typhoon Koppu intensified rapidly during the past 12 hours and it is making landfall near Baler in northern Luzon as the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  At 11:00 a.m. EDT on Saturday the center of Typhoon Koppu was located at latitude 16.0°N and longitude 122.9°E which put it about 170 miles (275 km) east-northeast of Manila, Philippines.  Koppu was moving toward the west-northwest at 7 m.p.h. (11 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 918 mb.  Typhoon Koppu has a Hurricane Intensity Index (HII) of 31.6, a Hurricane Size Index (HSI) of 17.5 and a Hurricane Wind Intensity Size Index (HWISI) of 49.1, which means it is capable of producing regional significant wind damage.  In addition the slow movement of Koppu means it will produce very heavy rainfall which will create the potential for serious flooding and landslides.

Koppu will continue to move toward the west-northwest for another 12 to 24 hours.  Then it will reach the western end of the subtropical ridge that has been steering it and start to move toward the north.  Although Typhoon Koppu will weaken as it moves across northern Luzon, it will be over that area for 36 to 48 hours.  Koppu has the potential to cause widespread damage due to winds, floods and landslides.

Typhoon Koppu Continues to Intensify and Threaten Luzon

Typhoon Koppu continued to intensify on Friday and it maintained its steady course toward northern Luzon.  At 5:00 p.m. EDT on Friday the center of Typhoon Koppu was located at latitude 15.8°N and longitude 124.5°E which put it about 270 miles (435 km) east-northeast of Manila, Philippines.  Koppu was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 947 mb.

Typhoon Koppu is evolving into a large well organized typhoon.  An eye has formed at the center of the circulation and multiple rain bands spiral around the core of the typhoon.  Upper level divergence is pumping mass away from the center of circulation.  Koppu is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is not much vertical wind shear.  Koppu is likely to continue to intensify until it begins to interact with northern Luzon.

A subtropical ridge is steering Koppu toward the west and that steering pattern is expected to continue for another 24 to 36 hours.  On its anticipated track the center of Typhoon Koppu will be very near the northeastern coast of Luzon in about 24 hours.  Koppu will bring strong winds, heavy rain and a storm surge to northern Luzon.  The large size of Koppu and its relatively slow movement means that it could produce very heavy rainfall.  Serious flooding and numerous mudslides are possible across northern Luzon.

Intensifying Typhoon Koppu Moving Toward Northern Luzon

Typhoon Koppu intensified on Thursday as it continued to move steadily toward Northern Luzon.  At 11:00 p.m. EDT the center of Typhoon Koppu was located at latitude 15.6°N and longitude 126.9°E which put it about 425 miles (685 km) east of Manila, Philippines.  Koppu was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 969 mb.

Typhoon Koppu is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds lessened on Thursday which decreased the vertical wind shear and allowed Koppu to intensify more quickly.  The core of the circulation consolidated and there are suggestions that an eyewall may be forming.  Koppu is expected to move through a favorable environment until it reaches northern Luzon and further intensification is very likely.

A subtropical ridge is steering Koppu toward the west and that general steering pattern is expected to continue for another 36 to 48 hours.  On its anticipated track, Typhoon Koppu will approach northern Luzon in 36 to 42 hours.  It could bring strong winds, heavy rain and a storm surge when it reaches that area.  The heavy rain could produce floods and mudslides as Koppu moves over northern Luzon.

Tropical Storm Champi Passing Through the Northern Marianas

Tropical Storm Champi is bringing gusty winds and heavy rain as it moves through the Northern Marianas.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Champi was centered near latitude 15.9°N and longitude 146.3°E which put it about 80 miles (135 km) east-northeast of Saipan.  Champi was moving toward the west at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 980 mb.  A Tropical Storm Warning remains in effect for Rota, Tinian, Saipan, Alamagan, Pagan and Agrihan.  The weather station at the airport on Saipan was reporting southwesterly winds at 46 m.p.h. (74 km/h) with gusts to 78 m.p.h. (126 km/h).

Although an upper level ridge north of Champi continued to cause vertical wind shear over the tropical storm, it slowly intensified on Thursday.  More thunderstorms formed near the center of circulation and those storms are generating more upper level divergence.  The core of the circulation is consolidating and more spiral bands are forming outside the core.  Champi is on the threshold of becoming a typhoon.  It is moving over water where the Sea Surface Temperature is near 29°C.  Champi is likely to move into an area where the upper level winds are lighter during the weekend and it will continue to intensify during the next several days.

A subtropical ridge is steering Champi toward the west and that motion is expected to continue for the next 12 to 24 hours.  After that time Champi will reach the western end of the ridge and turn toward the north.  Champi could be a strong typhoon south of Iwo To in about three days.

Tropical Storm Champi Intensifies, Warnings Issued for Northern Marianas

Tropical Storm Champi intensified on Wednesday and the National Weather Service issued watches and warnings for the northern Marianas.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Champi was located at latitude 15.5°N and longitude 151.9°E which put it about 450 miles (730 km) east of Saipan.  Champi was moving toward the west-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 984 mb.  Tropical Storm Warnings have been issued for Rota, Tinian, Saipan, Alamagan, Pagan and Agrihan.  A Typhoon Watch has been issued for Alamagan, Pagan and Agrihan.

The circulation of Tropical Storm Champi is still organizing.  An upper level ridge north of the tropical storm is causing easterly winds to blow over the top of Champi.  The resulting vertical wind shear is causing most of the stronger thunderstorms to form in the western half of the circulation.  Champi is over water where the Sea Surface Temperature is near 29°C.  The vertical wind shear will inhibit intensification on Thursday, but Champi could reach typhoon intensity within 24 hours.  It is expected to move into an area where the upper level winds are lighter on Friday and the rate of intensification could increase.

A subtropical ridge is steering Champi on a track that is a little north of due west.  That general motion is expected to continue for the next several days.  Champi will reach the western end of the subtropical ridge and turn toward the north later in the weekend.  On its anticipated track Champi will approach the northern Marianas in 24 to 30 hours.  It could bring strong winds and heavy rain to those islands.  Since the strongest thunderstorms are west of the center of circulation, conditions could start to deteriorate on some of the islands in less than 24 hours.

Tropical Storm Koppu Forms North of Yap

In spite of significant vertical wind shear a surface circulation has been consolidating inside an area of thunderstorms north of Yap.  The system has been designated Tropical Storm Koppu.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Koppu was located at latitude 15.7°N and longitude 137.1°E which put it about 430 miles (690 km) north of Yap.  Koppu was moving toward the west at 14 m.p.h. (23 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 993 mb.

Significant vertical wind shear is inhibiting the organization of Tropical Storm Koppu.  An upper level ridge north of Koppu is generating strong northeasterly winds over the top of the tropical storm.  The vertical wind shear is causing most of the strong thunderstorms to be located southwest of the center of circulation.  The only other deep convection is occurring in a band that is west of the core of the circulation.

Koppu is over water where the Sea Surface Temperature is near 30°C and so there is plenty of energy in the upper ocean.  The wind shear will inhibit intensification for another 24 to 48 hours before it starts to subside.  Koppu could intensify much more quickly later this week when it moves into an area where the upper level winds are lighter.  Koppu could become a typhoon withing 36 to 48 hours and it could be a strong typhoon by the end of the week.

A subtropical ridge is steering Tropical Storm Koppu quickly to the west.  That general motion is expected to continue for the rest of the week.  On its anticipated track Koppu could be approaching northern Luzon in about three or four days.  It could be a significant typhoon by that time.

Tropical Storm Nora Moves Into the Central Pacific

Tropical Storm Nora moved west of longitude 140°W on Sunday which meant that it officially crossed from the Eastern North Pacific into the Central North Pacific Ocean.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Nora was located at latitude 13.5°N and longitude 143.8°W which put it about 860 miles (1385 km) east-southeast of Hilo, Hawaii.  Nora was moving toward the west-northwest at 9 m.p.h. (15 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 m.p.h.).  The minimum surface pressure was 993 mb.

Nora is a small tropical storm.  Wind to tropical storm force only extend out about 70 miles (110 km) from the center of circulation.  Most of the stronger thunderstorms are located northwest of the center of circulation and there is not much deep convection in the other parts of Nora.  Although Nora is over water where the Sea Surface Temperature is near 29°C, southerly winds in the upper levels appear to be causing vertical wind shear.  The wind shear is likely to increase as an upper level trough north of Hawaii gets closer to Nora.

Tropical Storm Nora is nearing the western end of a subtropical ridge which has been steering it toward the west.  If the vertical structure of Nora remains intact, the tropical storm should turn toward the north during the next day or two.  After that time the upper level trough north of Hawaii could sweep Nora toward the northeast.  An alternate and possibly more likely scenario, given the small size of Tropical Storm Nora, is that the vertical wind shear blows the upper portion of the circulation north of the surface circulation.  If that happens, then the surface circulation will be steered westward until it dissipates by the winds in the lower atmosphere.