Kilo and Loke Weaken to Tropical Depressions

Both Tropical Storms Kilo and Loke weakened on Saturday and were downgraded to tropical depression status.  At 5:00 p.m. EDT on Saturday the center of Tropical Depression Kilo was located at latitude 14.2°N and longitude 159.4°W which put it about 500 miles (805 km) south-southwest of Honolulu, Hawaii.  Kilo was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 m.p.h.).  The minimum surface pressure was 1005 mb.

At 5:00 p.m. EDT on Saturday the center of Tropical Depression Loke was located at latitude 18.1°N and longitude 178.6°W which put it about 700 miles (1130 km) south of Midway Island.  Loke was moving toward the northwest at 8 m.p.h.  The maximum sustained wind speed was 35 m.p.h. (55 km/) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1003 mb.

Kilo appeared to be affected by vertical wind shear for much of Saturday.  A reconnaissance aircraft had a difficult time trying to find a surface circulation center and the spiral bands were not well developed.  Upper level easterly winds appeared to be pushing the tops of thunderstorms west of the low level circulation and inhibiting the formation of a warm core in the upper levels.  Recent satellite imagery suggests that more thunderstorms could be forming closer to the center of Kilo.  The vertical wind shear is forecast to decrease and Kilo could strengthen during the next few days.  A subtropical ridge is steering Kilo westward, but the ridge is expected to weaken and the steering currents could become weaker on Sunday.  Eventually, an upper level trough approaching from the northwest is forecast to pull Kilo toward the northeast early next week.

Loke appears to be very well organized for a tropical depression.  A primary rainband wraps around the western and southern side of the center of circulation and there appears to be about three quarters of an eyewall trying to form around the center.  The thunderstorms in the band are generating upper level divergence.  Loke is over warm Sea Surface Temperatures.  However, an upper level trough northwest of Loke is generating some southwesterly winds that are creating some vertical wind shear and are inhibiting upper level divergence south of the center of circulation.  That same upper level trough is expected to steer Loke toward the north-northeast during the next few days.  On it anticipated track Loke could be near Midway Island in about 60 hours.

Typhoon Goni Heading Toward Western Japan

Typhoon Goni turned north-northeastward and began moving toward western Japan on Saturday.  At 5:00 p.m. EDT on Saturday the center of Typhoon Goni was located at latitude 22.7°N and longitude 123.4°E which put it about 270 miles (435 km) southeast of Taipei, Taiwan and about 410 miles (660 km) southwest of Okinawa.  Goni was moving toward the north-northeast at 11 m.p.h. (18 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 967 mb.

The circulation of Typhoon Goni continues to be well organized.  It has a small eye with a fairly continuous eyewall surrounding it.  There are multiple spiral bands and the strongest band is about 60 miles east of the center of circulation.  There is upper level divergence pumping out mass.  Goni is moving over warm Sea Surface Temperatures and the upper level winds are relatively light.  The environment is favorable for intensification and modest intensification is possible during the next day or so.

Goni is moving around the western end of a subtropical ridge which is steering it toward the north-northeast.  That steering pattern is expected to continue for another two or three days.  On its anticipated track Goni will be near Ishigaki Jima in about 12 hours.  It could be just west of Okinawa in about 30 hours and it could be approaching Kyushu in about 48 hours.  Goni will bring strong winds and heavy rains to any places in its path.

Typhoon Goni Turning North, May Threaten Okinawa

Typhoon Goni is slowly turning toward the north and moving away from northern Luzon.  At 5:00 p.m. EDT on Friday the center of Typhoon Goni was located at latitude 19.8°N and longitude 122.5°E which put it about 330 miles (530 km) south-southeast of Taipei, Taiwan and about 615 miles (990 km) southwest of Okinawa.  Goni was moving toward the north at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 105 m.p.h. (120 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 956 mb.

Typhoon Goni will still be moving over warm Sea Surface Temperatures for the next several days and it has a chance to intensify.  The upper level winds are relatively light over the typhoon and there is not much vertical wind shear along its immediate path.  There appears to be an upper level outflow channel to the northeast.  Given the favorable environment Goni could intensify on Saturday.

Goni is moving around the western end of a subtropical high pressure system and it should begin to move toward the northeast a little more quickly.  On its anticipated track Goni could be near Ishigaki Jima in about 36 hours and near Okinawa in about 48 hours.  It could still be a strong typhoon at that time.  Goni could still by a typhoon when it approaches southwestern Kyushu in about three days.

Tropical Storms Kilo and Loke Form Over the Central Pacific

Two tropical storms formed over the Central Pacific Ocean on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Kilo was located at latitude 13.0°N and longitude 153.3°W which put it about 480 miles (770 km) south-southeast of Hilo, Hawaii.  Kilo was moving toward the west-northwest at 16 m.p.h. (26 km/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 1004 mb.

At 5:00 p.m. EDT on Friday the center of Tropical Storm Loke was located at latitude 16.4°N and longitude 177.2°W which put it about 815 miles (1310 km) south of Midway Island.  Loke was moving toward the north at 6 m.p.h. (9 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 55 m.p.h. (90 km/h).  The minimum surface pressure was 1000 mb.

Tropical Storm Kilo is not very well organized at the present time.  Strong easterly winds in the upper levels are blowing the tops off of the thunderstorms and the vertical wind shear is keeping Kilo from intensifying.  If the shear decreases as some numerical models forecast, then Kilo could intensify.  On the other hand, if the shear stays strong, then Kilo could weaken to a tropical depression.  If Kilo intensifies as some models suggest, then it could be pushed toward the western Hawaiian Islands.  However, if Kilo stays weaker, then winds lower in the atmosphere could steer more toward the west and keep it south of Hawaii.

Tropical Storm Loke is better organized, although most of the stronger thunderstorms are north of the center.  An upper level trough northwest of Loke could be creating some southwesterly winds around the tropical storm.  Although the vertical wind shear may be slowing the rate of intensification, Loke does appear to be getting stronger.  The upper level trough is expected to steer Loke toward the north and it could approach Midway Island in four or five days.  Loke could be a hurricane at that time.

Danny Becomes a Major Hurricane

Hurricane Danny intensified quickly and a NOAA plane investigating it on Friday afternoon found that Danny had maximum sustained winds of 115 m.p.h.  That made Danny a Category 3 hurricane on the Saffir-Simpson Scale which also made it a Major Hurricane.  At 5:00 p.m. EDT on Friday the center of Hurricane Danny was located at latitude 14.5°N and longitude 49.1°W which put it about 860 miles (1390 km) east of the Leeward Islands and about 2140 miles (3450 km) east-southeast of Miami, Florida.  Danny was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 115 m.p.h. (165 km/h) and there were wind gusts to 135 m.p.h. (195 km/h).  The minimum surface pressure was 974 mb.  Danny had a Hurricane Intensity Index (HII) of 20.6, a Hurricane Size Index (HSI) of 6.0, and a Hurricane Wind Intensity Size Index (HWISI) of 26.6

Danny remains a very small hurricane.  It is about two thirds of the size that Hurricane Charley was when it hit southwest Florida in 2004.  Danny may be starting to weaken.  The small eye is no longer visible on satellite images.  Southwesterly winds in the upper levels may be generating some vertical wind shear and those winds may also be inhibiting upper level divergence on the western side of Danny.  The small size of Danny means that it could weaken almost as fast as it intensified, if the shear increases.  Danny will move over warmer water when it passes west of longitude 55°W, which could slow the rate of weakening in about 36 hours.

Danny is being steered toward the west-northwest by a subtropical ridge located north of the hurricane.  The ridge is expected to strengthen in two or three days and steer Danny more toward the west after that time.  On its anticipated track Danny could be approaching the northern Leeward Islands in about two and a half days and it could be near Puerto Rico in about three and a half days.

Tiny Danny Quickly Intensifies Into a Hurricane

Tiny Tropical Storm Danny intensified quickly during the past 12 hours and the National Hurricane Center upgraded it to hurricane status in its 11:00 a.m. EDT advisory on Thursday.  At 11:00 a.m. EDT on Thursday the center of Hurricane Danny was located at latitude 12.5°N and longitude 44.8°W which put it about 1090 miles (1755 km) east of the Windward Islands and about 2480 miles (4000 km) east-southeast of Miami.  Danny was moving toward the west-northwest at 12 m.p.h. (19 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 992 mb.

The core of Hurricane Danny organized quickly on Thursday.  An eye formed in the center of the circulation and a ring of thunderstorms developed around the eye.  The circulation around Danny is very small.  Hurricane force winds only extend out about 12 miles (19 km) from the center and tropical storm force winds only extend 60 miles (95 km) from the center.  The Hurricane Size Index (HSI) for Danny is only 4.2.

The environment around Danny remains complex.  It is over water where the Sea Surface Temperature (SST) is near 28°C and the upper level winds are very light.  Upper level divergence is being produced by the thunderstorms around the eye.  On the other hand, slightly cooler SSTs and drier air are just to the north of Danny.  In addition, small hurricanes like Danny can be strongly affected by changes in their environment and they can intensify or weaken very quickly.  The environment would seem to support further intensification, but if Danny moves a little farther north, it could move into a more hostile environment.

Danny is being steered toward the west-northwest by the subtropical ridge to its north and that general steering pattern is expected to continue for another two or three days.  Late in the weekend the subtropical ridge is forecast to strengthen and steer Danny more toward the west.  On its anticipated track Danny could be near the Leeward Islands in about four days and near Puerto Rico in about five days.

Typhoon Goni Moving Closer to Northern Luzon and Taiwan

Typhoon Goni moved steadily westward on Wednesday and it got closer to northern Luzon and Taiwan.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Goni was located at latitude 18.9°N and longitude 125.3°E which put it about 350 miles (565 km) southeast of Taipei, Taiwan.  Goni was moving toward the west 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 Goni intensified on Wednesday and it is a very well organized tropical cyclone.  It has a large well formed eye.  The circulation is symmetrical although there are more thunderstorms in the south half of the typhoon.  Upper level divergence is well developed and it is pumping out mass in all directions.  Goni remains over warm Sea Surface Temperatures and the upper level winds are relatively light.  Some further intensification is possible during the next day or so.  Goni could run into stronger upper level winds in two or three days which would create more vertical wind shear and start to weaken the typhoon.

A subtropical ridge has been steering Goni toward the west and it is expected to do so again on Thursday.  However, Goni is nearing the western end of the ridge and it is forecast to turn to the north on Friday.  Goni appears to have moved more slowly during the past few hours, which may be an indication that it is reaching the western end of the ridge.  An upper level trough northwest of Goni is expected to turn Goni toward the northeast during the weekend and then accelerate it toward western Japan.

On its anticipated track, the center of Goni is expected to pass northeast of Luzon.  However, the circulation is large enough that some of northern Luzon could experience strong winds and heavy rain.  The center of Goni is forecast to pass east of Taiwan, but it could also bring strong winds heavy rain to some locations there as well.  The core of Goni could pass very near Ishigaki Jima and bring very strong winds and heavy rain to the islands in that area.

Tropical Storm Danny Heading West

Tropical Storm Danny has moved steadily westward during the past 24 hours.  At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Danny was located at latitude 11.2°N and longitude 41.1°W which put it about 1385 miles (2235 km) east of the Lesser Antilles and about 2740 miles (4410 km) east-southeast of Miami, Florida.  Danny was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1000 mb.

The organization of the circulation of Danny has varied during the past day.  It has a visible tight core at the center, but earlier today there was no convection around the core.  Recent satellite images show new thunderstorms developing near the core.  The environment around Danny is complex and it contains both positive and negative factors.  Danny is currently over water where the Sea Surface Temperature (SST) is near 28°C.  However, there is slightly cooler water just to the north of the tropical storm.  Satellite imagery indicates that there could also be drier air north of the circulation and some of that drier air could be pulled into Danny.  The upper level winds are light and upper level divergence is occurring.  However, a surge in the low level trade winds is about 250 miles (400 km) east of Danny.   If the surge in the trade winds reaches the core of Danny, it could push the lower part of the circulation out ahead (to the west) of the upper part of the circulation.  In that case Danny would weaken.

The complexity of the environment around Tropical Storm Danny makes the intensity forecast challenging.  If the trade wind surge does not reach the core of Danny and it stays over warm SSTs, then gradual intensification is possible.  On the other hand, if Danny moves more northward over cooler SSTs and into drier air, or if the trade wind surge creates more vertical wind shear, then Danny could weaken.

A subtropical ridge to the north of Danny is steering Danny toward the west and a generally west or west-northwest motion is forecast for the next few days.  If Danny is a little stronger, it could move a little farther north, and if it is weaker, it could stay farther south.  On its anticipated track, Danny could approach the Lesser Antilles in four or five days.  Interests in those areas should monitor Danny for future developments.

Typhoon Atsani Reaches Equivalent of Cat. 5 Hurricane

Typhoon Atsani intensified over the past 24 hours and it is now the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  At 8:00 a.m. EDT on Wednesday the center of Typhoon Atsani was located at latitude 19.6°N and longitude 151.3°E which put it about 1340 miles (2160 km) southeast of Tokyo, Japan.  Atsani was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 185 m.p.h. (300 km/h).  The minimum surface pressure was 918 mb.

Atsani is in an environment that is very favorable for tropical cyclones.  The Sea Surface Temperature (SST) is near 28°C.  The upper level winds are very light and there is almost no vertical wind shear.  Upper level divergence is pumping out mass in all directions and Atsani has a very circular appearance with a large eye evident on satellite imagery.  There are more rainbands and thunderstorms in the southern half of the circulation which is probably the result of warmer, moister air in area.

Atsani could maintain its current intensity for another 24 hours or so, although an eyewall replacement cycle will cause weakening if one occurs.  In another day or two the typhoon will start to move over cooler SSTs.  In addition as Atsani moves northward, it will start to be affected by the upper level westerlies in the middle latitudes.  Those winds will increase wind shear and weaken Atsani further.

Atsani is moving around the western end of a subtropical ridge which is steering it toward the northwest.  That general motion is expected to continue for another couple of days.  When Atsani reaches the western end of the ridge it will start moving toward the north.  Eventually, the upper level westerly winds will accelerate Atsani off to the northeast.  On its anticipated track Atsani would pass north of the Marianas and northeast of Iwo To.  At the current time the center of Atsani is forecast to pass about 100 miles east of ChiChi Jima.  However, a slight deviation of the track toward the west could bring Atsani closer to Chichi JIma and Iwo To.

 

Tropical Depression 4 Forms over Eastern Atlantic

As the calendar reaches mid-August, the environment over the tropical Atlantic Ocean typically becomes more favorable for tropical cyclone formation.  The Sea Surface Temperature warms and vertical wind shear decreases.  Despite the ongoing El Nino in the tropical Pacific Ocean, we are seeing the typical pattern develop in the Atlantic for this time of year.  A low level circulation within an area of thunderstorms over the eastern Atlantic Ocean became better organized on Tuesday and the National Hurricane Center classified the system as Tropical Depression Four (TD4).  At 11:00 a.m. EDT on Tuesday the enter of Tropical Depression Four was located at latitude 10.6°N and longitude 36.5°W which put it about 1665 miles (2765 km) east of the Windward Islands.  TD4 was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 35 m.p.. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1009 mb.

TD4 is currently in an environment that is favorable for intensification.  The upper level winds are light and the thunderstorms are generating upper level divergence in all directions.  It is currently over water where the Sea Surface Temperature is near 28°C.  As long as TD4 moves westward, it will stay over warmer water and intensification will be likely.  If TD4 were to move more toward the northwest, then it would move over slightly cooler water and less intensification would occur.  Since TD4 is forecast to move west, it is expected to become Tropical Storm Danny, and it could be a hurricane later this week.

A subtropical ridge north of TD4 is steering it toward the west and that steering motion is expected to continue for the next 24 to 48 hours.  Later this week an upper level trough passing north of the ridge is expected to weaken the ridge, which could cause TD4 to move northwesterly for a day or so.  After the upper level trough moves off to the east, the subtropical ridge is forecast to steer TD4 back more toward the west.  On its anticipated track TD4 is expected to be east of the Windward Islands this weekend.