Author Archives: jay_hobgood

Typhoon Soudelor Becomes Equivalent of a Category 5 Hurricane

Typhoon Soudelor continued to intensify rapidly on Monday and it reached the equivalent of a Category 5 Hurricane on the Saffir-Simpson Scale.  At 5:00 p.m. EDT on Monday the center of Typhoon Soudelor was located at latitude 18.0°N and longitude 140.1°E which put it about 1020 miles (1640 km) east-southeast of Okinawa.  Soudelor was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 215 m.p.h. (350 km/h).  The minimum surface pressure was 907 mb.  The Hurricane Intensity Index (HII) for Soudelor was 40.4, the Hurricane Size Index was 13.6 and the Hurricane Wind Intensity Size Index was 54.0.  These indices mean that Soudelor is capable of producing regional catastrophic damage.

The upper level winds around Soudelor are very light and there is almost no vertical wind shear.  The typhoon has strong upper level divergence in all directions which is pumping out mass and causing the surface pressure to decrease rapidly.  It is over water where the Sea Surface Temperature is near 31°C and the circulation is extracting plenty of energy from the upper ocean.  The environment would support further intensification, but Soudelor is already a very powerful typhoon.  Soudelor rapidly completed an eyewall replacement cycle earlier today and future cycles could produce fluctuations in intensity.  Soudelor could remain a very intense typhoon for several more days.

A strong subtropical ridge is steering Typhoon Soudelor toward the west-northwest and that general steering pattern is expected to continue for the next few days.  On its anticipated track Soudelor could be near the southernmost islands of Japan in three days, near northern Taiwan in four days and near the coast of China in less than five days.  Although it is likely to weaken before it reaches any of those locations, it could still be a powerful typhoon at that time.

Hurricane Guillermo Weakening As It Moves Toward Hawaii

A reconnaissance aircraft confirmed a weakening trend in Hurricane Guillermo that had been suggested by satellite imagery.  At 11:00 p.m. EDT on Sunday the center of Hurricane Guillermo was located at latitude 15.5°N and longitude 145.0°W which put it about 725 miles (1165 km) east-southeast of Hilo, Hawaii.  Guillermo was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 85 m.p.h. (145 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 981 mb.

An upper level trough north of Guillermo is producing southwesterly winds over the top of the circulation.  Those winds are causing vertical wind shear and are inhibiting the upper level divergence on the western side of the circulation.  In addition Guillermo is gradually moving over cooler Sea Surface Temperatures (SSTs).  A combination of wind shear and cooler SSTs will continue to weaken the hurricane.

A subtropical ridge is steering Guillermo toward the west-northwest and that general motion is expected to continue.  On its anticipated track Guillermo would approach the Big Island of Hawaii in about 72 hours.  It will likely be a tropical storm at that time.

Typhoon Soudelor Intensifies Rapidly and Moves Over Saipan

Typhoon Soudelor intensified rapidly during the 12 hours before it moved directly over Saipan.  At 11:00 a.m. EDT on Sunday the center of Typhoon Soudelor was located at latitude 15.3°N and longitude 145.3°E which put it about 25 miles (40 km) west-northwest of Saipan.  It was moving toward the west-northwest at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 956 mb.  The airport on Saipan measured sustained wind to 54 m.p.h. (87 km/h) and wind gusts to 91 m.p.h. (147 km/h).  However, there were several observations when no wind speed was reported.  The minimum surface pressure reported was 958 mb.

Typhoon Soudelor organized quickly after the primary band wrapped completely around the center of circulation.  A tiny (4 mile wide) pinhole eye developed at the center of circulation and there are multiple bands of thunderstorms rotating around the center.   Soudelor is over warm Sea Surface Temperatures and there is little vertical wind shear.  Further intensification is likely and Soudelor could reach Super Typhoon status.

A subtropical ridge is steering Soudelor toward the west-northwest and that general motion is expected to continue for the next few days.  On its anticipated track Soudelor could approach the southernmost islands of Japan or Taiwan in four or five days.

Hurricane Guillermo Crosses Into the Central Pacific

Hurricane Guillermo moved west of longitude 140°W on Saturday, which means it officially crossed into the Central Pacific Ocean.  The responsibility for issuing advisories on Guillermo shifted from the National Hurricane Center in Miami, Florida to the Central Pacific Hurricane Center in Honolulu, Hawaii when Guillermo moved west of 140°W.  At 11:00 p.m. EDT on Saturday the center of Hurricane Guillermo was located at latitude 14.0°N and longitude 141.0°W which put it about 1010 miles (1625 km) east-southeast Hilo, Hawaii.  Guillermo was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 970 mb.

The structure of Hurricane Guillermo appeared to become less organized on Saturday.  There are fewer thunderstorms and the spiral bands appear to be weaker.  Guillermo is nearing water where the Sea Surface Temperature is near 27°C, and it will gradually move over even cooler water.  Westerly winds in the upper levels appear to be generating some vertical wind shear over the northern portion of the circulation.  Guillermo is still producing upper level divergence near the center of circulation, but the divergence appears to less over the western half of the hurricane.  The circulation may be pulling some drier more stable air into the western part of the circulation.  Guillermo will be moving into a less favorable environment and weakening is likely.

A subtropical ridge is steering Guillermo toward the west-northwest and that general motion is expected to continue during the next several days.  On its anticipated track Guillermo could approach the Big Island of Hawaii in about four days.  It is likely to be a tropical storm at that time.

Soudelor Almost a Typhoon as It Nears the Marianas

Tropical Storm Soudelor intensified on Saturday and it has almost reached typhoon status.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Soudelor was located at latitude 14.8°N and longitude 147.7°E which put it about 170 miles (275 km) east-southeast of Saipan.  Soudelor was moving toward the west-northwest at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 978 mb.  A Typhoon Warning has been issued for Saipan and Tinian.  A Tropical Storm Warning has been issued for Rota.  A Typhoon Watch has been issued for Agrihan, Pagan and Alamagan.

The structure of Tropical Storm Soudelor improved on Saturday.  A long spiral band wrapped almost entirely around the center of circulation and numerous other spiral bands were apparent on satellite imagery.  There are more thunderstorms on the western side of the circulation.  Soudelor is moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of the tropical storm is causing light easterly winds over the circulation.  However, the vertical wind shear is modest and upper level divergence is increasing.  Soudelor is in a favorable environment.  Further intensification is likely and rapid intensification is possible.  Soudelor will very likely be a typhoon when it moves through Marianas.

A subtropical ridge is steering Soudelor toward the west-northwest and that pattern is expected to continue during the next few days.  On its anticipated track Soudelor will be near Saipan and Tinian in about 12 hours.  It could bring strong winds to those locations and other nearby islands.

Guillermo Intensifies Into a Hurricane

Guillermo intensified rapidly during the past 24 hours and it is now a hurricane.  At 5:00 p.m. EDT on Friday the center of Hurricane Guillermo was located at latitude 12.7°N and longitude 134.8°W which put it about 1430 miles (2300 km) east of Hilo, Hawaii.  Guillermo was moving toward the west-northwest at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 970 mb.

Guillermo moved through a very favorable environment of warm Sea Surface Temperatures and little vertical wind shear which allowed it to intensify rapidly from a tropical storm into a hurricane.  An eye was visible earlier today on satellite images, but it is either obscured or has filled with clouds on the most recent images.  The hurricane is moving over water where the Sea Surface Temperature (SST) is near 29°C.  The upper level winds are light, but the rapid movement toward the west-northwest may be generating some vertical wind shear.  If Guillermo moves more slowly, it has about another 24 hours before it starts to move over cooler SSTs.  Once Guillermo gets west of longitude 140°W, it will gradually move over cooler SSTs.  As it moves farther north, it will also get closer to stronger upper level winds blowing from the west.  The combination of cooler SSTs and more vertical wind shear are likely to weaken Guillermo as it approaches Hawaii.

A subtropical ridge north of Guillermo is steering the hurricane toward the west-northwest and that steering is likely to continue for several more days,  In a few days a trough approaching from the west will turn Guillermo toward the northwest.  On its anticipated track Guillermo could approach Hawaii in about five days.  The higher probability is that a weaker Guillermo will move north of Hawaii, but the guidance from numerical models has been changing today.

Tropical Storm Guillermo Forms East- Southeast of Hawaii

An area of low pressure organized on Wednesday well east-southeast of Hawaii and it has been classified as Tropical Storm Guillermo.  At 5:00 a.m. EDT on Thursday the center of Tropical Storm Guillermo was located at latitude 8.5°N and longitude 126.3°W which put it about 2070 miles (3340 km) east-southeast of Hilo, Hawaii and about 1475 miles (2370 km) southwest of the southern tip of Baja California.  Guillermo was moving toward the northwest 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.

Guillermo formed at an unusually low latitude over the eastern North Pacific.  It is over an area where the Sea Surface Temperatures (SSTs) are near 29°C.  The upper level winds are light over the circulation and there is not much vertical wind shear.  Guillermo will be moving through an environment favorable for intensification during the next two or three days and a period of rapid intensification will be possible when it nears hurricane intensity.  Guillermo will move over cooler SSTs when it gets closer to Hawaii and the wind shear may also increase.

A subtropical ridge north of Guillermo is steering the tropical storm toward the northwest and the ridge is expected to continue to steer the tropical storm toward the west-northwest during the next 48 to 72 hours.  Later in the weekend an upper level trough approaching from the west could turn Guillermo more toward the northwest.

Tropical Cyclone 02B Forms Near Bangladesh

An area of low pressure over the extreme northern portion of the Bay of Bengal developed enough characteristics of a tropical cyclone to be designated Tropical Cyclone 02B.  At 5:00 a.m. EDT on Wednesday the center of Tropical Cyclone 02B was located at latitude 21.3°N and longitude 91.4°E which put it about 80 miles south-southwest of Chittagong, Bangladesh.  It was moving toward the north-northeast at 4 m.p.h.  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1001 mb.

The circulation around Tropical Cyclone 02B slowly organized during the past several days and it now has the structure of a tropical cyclone.  There are several spiral bands of thunderstorms, although most of the thunderstorms are south of the center due to the proximity to land.  The tropical cyclone is over very warm water where the Sea Surface Temperature is near 31°C, and it has enough energy to intensify.  However, a large upper level ridge over Asia is generating moderate northeasterly winds over the circulation which is producing moderate vertical wind shear.  Proximity to land will also be an inhibiting factor.  Some modest intensification is possible before the center moves over land.

Tropical cyclone 02B is moving around the western end of a subtropical ridge which is steering it northward toward the coast of Bangladesh.  That general steering pattern is expected to continue for another 24 hours.  Then the easterly winds associated with the upper level ridge over Asia are expected to turn Tropical Cyclone 02B toward the west.  On its anticipated track Tropical Cyclone 02B could make landfall over Bangladesh in approximately 24 hours.  Given the bathymetry of the northern Bay of Bengal and the shape of the coast of Bangladesh some storm surge is possible.  Locally heavy rainfall could contribute to flooding as the tropical cyclone moves inland.

Typhoon Halola Nearing Ryukyu Islands

Typhoon Halola turned northwestward on Friday and it is nearing the Ryukyu Islands.  At 5:00 p.m. EDT on Friday the center of Typhoon Halola was located at latitude 25.8°N and longitude 130.2°E which put it about 185 miles (300 km) east-southeast of Okinawa and about 50 miles (80 km) west-southwest of Minamidiato Island.  Halola was moving toward the northwest at 7 m.p.h. (11 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 974 mb.

Halala weakened on Friday, but it was still a typhoon at the time of this post.  It has a well defined low level circulation, but there are fewer thunderstorms in northwestern portion of Halola.  It appears as if some drier air is moving into the northwestern side of the typhoon.  Upper level winds from the northeast are creating some vertical wind shear, but Halola has well developed upper level divergence to the south of the center.  Halola will move over water where the Sea Surface Temperature (SST) is near 28°C as it passes just north of Okinawa and it could stay at typhoon intensity for another 12 to 24 hours.  After that time it will move over cooler SSTs and the upper level winds will increase.  Halola is likely to weaken to a tropical storm over the weekend.

Typhoon Halola is moving around the western end of a subtropical ridge, which is why it has turned toward the northwest.  It will turn northward on Saturday and then turn northeastward in about 36 hours as strong upper level winds from the southwest begin to push it in that direction.  On its anticipated track the center of Typhoon Halola could pass between Okinawa and Amami in to 18 hours.  It is likely to bring wind and heavy rain to some of the Ryukyu Islands.  The center of Halola could be near or just west of Kyushu in about 36 hours.

Tropical Storm Felicia Forms Southwest of Baja California

A center of circulation finally developed in an area of thunderstorms southwest of Baja California and the system has been designated as Tropical Storm Felicia.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Felicia was located at latitude 19.1°N and longitude 114.9°W which put it about 415 miles (670 km) southwest of the southern tip of Baja California.  The maximum sustained wind speed was 40 m.p.h. (60 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.

Felicia is not a particularly well organized tropical storm.  Most of the thunderstorms are forming in the southern half of the circulation and it does not have many spiral bands.  Recent satellite images seem to indicate that upper level divergence is beginning to occur.  Felicia is over water where the Sea Surface Temperature (SST) is near 27°C and the upper level winds do not appear to be too strong.  The potential for some intensification will exist for about another 24 hours.  In a day or so, Felicia will start to move over cooler SSTs and it will likely weaken by the weekend.

A subtropical ridge is steering Felicia toward the northwest and that general steering pattern is expected to continue as long as the vertical integrity of the circulation remains intact.  When Felicia moves over cooler SSTs, the height of the circulation will decrease and the storm will be steered by winds in the lower levels.  Those winds are expected to turn Felicia more toward the west in a day or two.  Felicia poses no threat to land at this time.