Typhoon Goni Heading West

Typhoon Goni moved steadily westward away from the Mariana Islands on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Goni was located at latitude 18.3°N and longitude 135.3°E which put it about 780 miles (1260 km) southeast of Okinawa.  Goni was moving toward the west at 19 m.p.h. (31 km/).  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.

Goni appeared to go through an eyewall replacement cycle on Monday which resulted in a reduction in the maximum wind speed.  As the tiny pinhole inner eye weakened, the stronger winds were located in the larger outer eyewall.  The reduction in wind speed could be temporary, if the outer eye begins to contract.  Goni remains in a favorable environment.  It is moving over warm Sea Surface Temperature and the vertical wind shear is very modest.  The circulation is producing upper level divergence in all directions.  Goni will remain in a favorable environment for another two or three days and it should remain strong during that time period.

A subtropical ridge is steering Goni toward the west-northwest and that steering pattern is expect to continue for another 48 to 72 hours.  Later this week an upper level trough could approach the typhoon from the northwest.  Southwesterly winds on the eastern side of the trough could turn Goni toward the north later this week. On its anticipated track Goni could be near Taiwan, the northern Philippines or Okinawa when it makes that turn.

Typhoon Atsani Getting Bigger and Stronger

Typhoon Atsani continued to grow bigger and stronger on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Atsani was located at latitude 16.3°N and longitude 155.8°E which put it about 1700 miles (2740 km) southeast of Tokyo, Japan.  Atsani was moving west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 937 mb.

Typhoon Atsani has a very well organized circulation.  It is very symmetrical with a well formed eye and eyewall and it has multiple rainbands spiraling around the center of circulation.  Upper level divergence is pumping out mass in all directions, which is allowing the surface pressure to decrease.  There is little vertical wind shear and Atsani is moving over warm Sea Surface Temperatures.  Further intensification is likely, although eyewall replacement cycles could cause fluctuations in intensity.

A subtropical ridge is steering Atsani toward the northwest and that general steering pattern is expected to continue for the next few days.  On its anticipated track Atsani will pass north of the Marianas and it could be east of Iwo To in three or four days.

Goni Intensifies Rapidly Into a Strong Typhoon

Goni intensified rapidly from a tropical storm into a strong typhoon on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Goni was located at latitude 16.7°N and longitude 141.1°E which put it about 265 miles (425 km) west of Anatahan.  Goni was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) which made Goni the equivalent of a major hurricane.  There were wind gusts to 160 m.p.h. (260 km/h) and the minimum surface pressure was 937 mb.

The circulation of Goni organized quickly on Sunday and it was able to intensify rapidly.  The primary rainband wrapped tightly around the center of circulation and a tiny pinhole eye formed in the center.  The band continued to wrap about the core of the circulation and it could be about to form a second, larger concentric eyewall.  The structure of Goni looks a lot like the circulation of Typhoon Soudelor did when it intensified rapidly.  Light easterly winds in the upper levels enhanced divergence to the west of Goni and pumped out mass allowing the pressure to fall rapidly.

Goni is moving over water where the Sea Surface Temperatures are warm.  The vertical wind shear is minimal and further intensification is possible.  If concentric eyewalls form, eyewall replacement cycles could produce fluctuations in intensity.

A subtropical ridge is steering Goni toward the west-northwest and that general steering pattern is expected to continue for another three or four days.  At that time Goni could be near the western end of the subtropical ridge.  An upper level trough in the mid-latitude westerlies could approach the typhoon from the northwest and turn it toward the north.

Tropical Storm Goni Brings Wind and Rain to the Marianas

Tropical Storm Goni brought wind and rain to the Northern Marianas on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Goni was located at latitude 15.1°N and longitude 144.4°E which put it about 60 miles (95 km) west of Tinian.  Goni was moving toward the northwest at 10 m.p.h. (16 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 982 mb.  A Tropical Storm Warning continues for Guam, Rota, Tinian, and Saipan and a Typhoon Watch continues for Saipan and Tinian.

The center of Tropical Storm Goni passed between Rota and Tinian on Saturday.  The tropical storm brought wind and rain to the northern Marianas.  The airport on Saipan reported a wind gust to 56 m.p.h. (90 km/h).  The stormy conditions could have setback the recovery from damage caused by Typhoon Soudelor.

The circulation around Goni continued to organize on Saturday.  A primary spiral band wrapped around the center of circulation and there have been indications that an eye may be forming in the center.  An upper level ridge east of Goni is causing some easterly winds over the circulation and is creating some vertical wind shear.  The shear is limiting thunderstorm activity on the eastern side of the circulation.  As Goni moves farther west, the wind shear will decrease.  It is moving over water where the Sea Surface Temperature is near 29°C.  The favorable environment will cause intensification and a period of rapid intensification is possible.

A subtropical ridge is steering Goni toward the west-northwest and that general steering pattern is expected to continue for the next few days.  Goni will move farther west of the Marianas on Sunday and conditions there should gradually improve.

Tropical Storm Goni Prompts Watches for Marianas

Tropical Storm Goni formed east of the Marianas on Friday and watches were issued for some of the islands because of the imminent threat it posed.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Goni was located at latitude 13.0°N and longitude 148.0°E which put it about 235 miles (370 km) southeast of Saipan.  Goni was moving toward the west-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 996 mb.  A Typhoon Watch has been issued for Saipan and Tinian.  A Tropical Storm Watch has been issued for Guam and Rota.

The circulation of Tropical Storm Goni is still organizing.  Most of the thunderstorms are developing in the western half of the circulation.  An upper level ridge is generating easterly winds which are blowing across Goni and those winds are inhibiting the development of convection in the eastern part of the tropical storm.  Goni is moving over water where the Sea Surface Temperatures (SSTs) are near 29°C.  The environment supports intensification and Goni could intensify more rapidly in a day or two when the circulation is more well organized.  Goni could reach typhoon intensity within 48 hours.

A subtropical ridge is steering Goni toward the west-northwest and that general motion is expected to continue during the next few days.  On its anticipated track, the center of Goni could be very near Saipan in about 24 hours.  Goni could be a strong tropical storm on the verge of becoming a typhoon at that time.  Saipan is still recovering from the effects of Typhoon Soudelor.  Strong winds and heavy rain could set back those recovery efforts.

 

Shear Weakens Hilda, Tropical Storm Watch Dropped

Strong vertical wind shear weakened Tropical Storm Hilda again on Wednesday and the Tropical Storm Watch for the Big Island of Hawaii was discontinued by the Central Pacific Hurricane Center.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Hilda was located at latitude 17.2°N and longitude 152.4°W which put it about 245 miles (395 km) southeast of Hilo, Hawaii.  Hilda was moving toward the west at 4 m.p.h. (6 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 1003 mb.

An upper level low north of the Hawaiian Islands is generating very strong southwesterly winds that are blowing right over the top of Tropical Storm Hilda.  Those winds are blowing thunderstorms away from the core of the circulation.  The western half and inner core of Hilda consists of bands of low clouds rotating counterclockwise around the exposed center of circulation.  Thunderstorms continue to form in some of the bands northeast of the center of circulation, but the strong upper level winds quickly blow the tops off of those storms.  Since the upper level low isn’t moving, strong vertical wind shear is expected to continue and Hilda should slowly spin down.  It is likely to weaken to tropical depression status on Thursday.

As the circulation gets shallower, Hilda will be steered by the winds in the lower atmosphere.  Those winds are blowing from the east and the will push the tropical storm or its remnants toward the west.  On its anticipated track Hilda would pass south of Hawaii as a tropical depression during the next several days.

Weakening Hurricane Hilda Prompts Tropical Storm Watch for Hawaii

Although strong vertical wind shear is weakening Hurricane Hilda, its proximity to Hawaii has prompted the issuance of a Tropical Storm Watch.  At 11:00a.m. EDT on Tuesday the center of Hurricane Hilda was located at latitude 17.5°N and longitude 151.3°W which put it about 290 miles (470 km) east-southeast of Hilo, Hawaii.  Hilda was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/).  The minimum surface pressure was 985 mb.  The Central Pacific Hurricane Center in Honolulu has issued a Tropical Storm Watch for Hawaii County.

An upper level low north of the Hawaiian Islands is creating strong southwesterly winds that are blowing straight into Hurricane Hilda.  Although the circulation of Hilda appeared strong enough on Monday to deflect the upper level winds around it, those winds are tilting the vortex significantly to the east with height today.  The middle and upper portions of the hurricane’s circulation appear to still be attached to the lower level circulation, but they are tilted toward the east.  If the upper level winds get much stronger they could shear off the upper portion of the circulation from the lower level circulation.  The effect of the strong vertical wind shear is weakening Hurricane Hilda and that weakening is expected to continue during the next several days.  Hilda could weaken to tropical storm status within 24 hours and it could be a tropical depression in 48 to 72 hours.

A subtropical ridge northeast of Hilda and the upper low north of Hawaii are both affecting the movement of the hurricane.  The subtropical ridge is trying to push Hurricane Hilda toward the west, while the upper low is trying to push it to the northeast..  The combined effects of the ridge and the low are causing Hilda to move slowly northwestward.  If the strong upper level winds do shear the top off of Hilda, then winds in the lower atmosphere will steer the surface circulation toward the west.  Since Hilda could still be a minimal tropical storm when it approaches the Big Island of Hawaii, a Tropical Storm Watch has been issued.

Hurricane Hilda Weakening As it Moves Toward Hawaii

Hurricane Hilda weakened on Sunday as it move closer to Hawaii.  At 11:00 p.m. EDT on Sunday the center of Hurricane Hilda was located at latitude 15.3°N and longitude 148.2°W which put it about 545 miles (880 km) east-southeast of Hilo, Hawaii.  Hilda was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 970 mb.

An upper level low north of Hawaii is generating southwesterly winds which are causing vertical wind shear near Hurricane Hilda.  The wind shear is inhibiting the upper level divergence on the western side of the circulation and the hurricane is weakening.  As Hilda moves farther northwest the wind shear will increase and the hurricane will weaken more quickly.  Hilda could weaken below hurricane strength on Tuesday.

A subtropical ridge was steering Hilda toward the west-northwest.  The hurricane is near the western end of the ridge and the upper level southwesterly winds are pushing Hilda more toward the northwest.  The northwesterly motion is likely to continue while Hilda produces tall thunderstorms and the circulation extends through the troposphere.  If Hilda weakens to the point where it no longer produces tall thunderstorms, then it will be steered more toward the west by the winds in the lower levels of the atmosphere.

Hilda Speeds Into the Central Pacific and Becomes a Major Hurricane

Hurricane Hilda continued to move steadily westward on Saturday and when it moved west of longitude 140°W, Hilda officially crossed into the Central Pacific.  At that time the responsibility for issuing advisories on Hilda shifted from the National Hurricane Center in Miami, Florida to the Central Pacific Hurricane Center in Honolulu, Hawaii.  At 5:00 p.m. EDT on Saturday the center of Hurricane Hilda was located at latitude 13.7°N and longitude 143.5°W which put it about 870 miles (1400 km) east-southeast of Hilo, Hawaii.  Hilda was moving toward the west at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) which made Hilda a Category 4 hurricane on the Saffir-Simpson Scale and qualified it as a Major Hurricane.  There were wind gusts to 165 m.p.h. (270 km/h) and the minimum surface pressure was 946 mb.

Hilda is moving over water where the Sea Surface Temperature (SST) is near 28°C.  The upper level winds are light and there is not much vertical wind shear.  Although Hilda is a small hurricane, it is generating upper level divergence in all directions for the center.  Hilda will remain in a favorable environment for another day or so and it could intensify further during that time.  When it moves farther west, it will move into an area where upper level winds are blowing from the west.  Those winds will cause vertical wind shear and weaken Hilda.  Because of the small size of the circulation Hilda could weaken faster than a larger hurricane would.

A subtropical ridge is steering Hilda toward the west and that general steering pattern is expected to continue for another 24 to 48 hours.  When Hilda encounters the upper level westerly winds, those winds will deflect it onto a more northwesterly track.  When Hilda weakens and the thunderstorms do not extend as high, then winds in the lower levels will push it more toward the west again.

Typhoon Soudelor Making Landfall in China

Typhoon Soudelor crossed the Taiwan Strait and it is making landfall on the east coast of China near Quanzhou.  At 11:00 a.m. EDT on Saturday the center of Typhoon Soudelor was located at latitude 24.9°N and longitude 118.9°E which put it about 50 miles east of Quanzhou.  Soudelor was moving to the northwest at 10 m.p.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.

Soudelor weakened when it moved across Taiwan on Friday, but it was still a large typhoon when it made landfall in China.  Soudelor is expected to move toward the northwest while it moves farther inland over China.  Soudelor produced heavy rain when it moved over Taiwan and it could cause locally heavy rainfall over parts of eastern China before it dissipates.