Tropical Cyclone Keni Forms East of Vanuatu

Tropical Cyclone Keni formed east of Vanuatu on Sunday.  At 11:00 p.m EDT on Sunday the center of Tropical Cyclone Keni was located at latitude 16.9°S and longitude 172.0°E which put it about 215 miles (350 km) east of Port Vila, Vanuatu.  Keni was moving toward the east-southeast at 7 m.p.h. (11 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 994 mb.

A distinct center of circulation consolidated in an area of showers and thunderstorms between Vanuatu and Fiji on Sunday and the Fiji Meteorological Service designated the system as Tropical Cyclone Keni.   The circulation of Tropical Cyclone Keni organized quickly.  Several bands of thunderstorms wrapped part of the way around the center of circulation.  Other bands of showers and thunderstorms were revolving around the core of the circulation.  Storms near the center were generating upper level divergence which was pumping mass away from the tropical cyclone.

Tropical Cyclone Keni will move through an environment favorable for intensification during the next 24 hours.  Keni will move over water where the Sea Surface Temperature is near 28°C.  It is under a small upper level ridge and the upper level winds are weak.  So, there will be little vertical wind shear on Monday.  Tropical Cyclone Keni will intensify during the next 24 hours and it could become the equivalent of a hurricane/typhoon.

Tropical Cyclone Keni on the southwestern edge of a subtropical ridge which is steering Keni toward the east-southeast.  A general motion toward the east-southeast is expected to continue for another 24 to 36 hours.  On its anticipated track Tropical Cyclone Keni could be approaching Fiji within 24 hours.  Keni could be the equivalent of a hurricane/typhoon when it near Fiji.  Keni will bring gusty winds and locally heavy rain to parts of Fiji.  The heavy rain could cause flash floods in some locations.

Tropical Cyclone Iris Weakens East of Queensland

Tropical Cyclone Iris weakened over the Coral Sea east of Queensland on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone Iris was located at latitude 19.6°S and longitude 152.3°E which put it about 230 miles (370 km) east-northeast of Mackay, Australia.  Iris was moving toward the east-southeast 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 990 mb.

An upper level ridge east of Australia was producing strong northwesterly winds which were blowing toward the top of Tropical Cyclone Iris.  Those winds were causing strong vertical wind shear which weakened Iris on Wednesday.  The stronger thunderstorms were occurring in bands southeast of the center of circulation.  The bands in other parts of the circulation consisted primarily of showers and low clouds.  The wind shear was not quite strong enough to blow the top off of the circulation, but the shear was preventing upper level divergence on the northern side of Tropical Cyclone Iris.

Tropical Cyclone Iris will move over water where the Sea Surface Temperature is near 28°C.  So, there is enough energy in the upper ocean to support a tropical cyclone.  However, the upper level ridge will continue to cause strong vertical wind shear and Tropical Cyclone Iris is likely to slowly weaken during the next several days.

Tropical Cyclone Iris is moving slowly toward the east-southeast.  If the vertical wind shear blows the top half of the circulation away to the southeast, then Iris would be steered by the winds in the lower atmosphere.  A high pressure system in the lower atmosphere over Australia would begin to steer Tropical Cyclone Iris back toward the northwest.  On its anticipated track the center of Tropical Cyclone Iris is expected to remain east of Queensland.  Rainbands on the western periphery have occasionally brought rain to the coast of Queensland, but most of the rain is falling over the ocean.

Tropical Cyclone Iris Prompts Warnings for Queensland

The proximity of Tropical Cyclone Iris prompted the Australian Bureau of Meteorology to issued Warnings and Watches for the east coast of Queensland on Monday.  A Warning was issued for the portion of the coast from Ayr to Sarina including Mackay and the Whitsunday Islands.  A Watch was issued for the portion of the coast from Sarina to St. Lawrence.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone Iris was located at latitude 17.1°S and longitude 149.0°E which put it about 210 miles (335 km) northeast of Townsville, Australia.  Iris was moving toward the southeast at 3 m.p.h. (4 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.

The circulation of Tropical Cyclone Iris was asymmetrical.  Most of the showers and thunderstorms were located south and east of the center of circulation.  The bands north and west of the center consisted primarily of low clouds and showers.  Tropical Cyclone Iris was near the western end of an upper level ridge.  The ridge was producing northwesterly winds which were blowing toward the top of the circulation.  Those winds were producing moderate vertical wind shear and they were probably responsible for the asymmetrical distribution of thunderstorms.

Tropical Cyclone Iris will be moving through an environment marginally favorable for intensification during the next 48 hours.  Iris will move over water where the Sea Surface Temperature is near 29°C.  However, the upper level ridge will continue to produce moderate vertical wind shear.  The shear will be strong enough to inhibit intensification.  If the strength of the upper level winds slows, then Tropical Cyclone Iris could strengthen, but if the upper level winds get faster, then Iris will weaken.  The forecast is for slow intensification, but there is high uncertainty about the intensity forecast.

The subtropical ridge east of Iris is steering Tropical Cyclone Iris slowly toward the southeast.  A general motion toward the southeast is expected to continue for several more days.  On its anticipated track the center of Tropical Cyclone Iris is expected to stay east of the coast of Queensland.  However, Tropical Cyclone Iris could come close enough to the coast to bring gusty winds and locally heavy rain to locations under Warnings and Watches.

Tropical Cyclone Iris Redevelops East of Queensland.

Tropical Cyclone Iris redeveloped east of Queensland on Sunday night.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Iris was located at latitude 16.9°S and longitude 148.7°E which put it about 190 miles (310 km) east of Cairns, Australia.  Iris was moving toward the southwest at 8 m.p.h. (13 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 995 mb.

Tropical Cyclone Iris formed over the Coral Sea last week but wind strong vertical shear quickly weakened Iris into an area of low pressure.  The low pressure system meandered over the Coral Sea east of Australia during the past few days.  More thunderstorms developed near the center of circulation on Sunday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Iris again.

The circulation around Tropical Cyclone Iris was still reorganizing on Sunday night.  A distinct low level center of circulation was evident on visible satellite images.  More thunderstorms were developing near the center.  A primary rainband wrapped around the northern, eastern and southern sides of the center of circulation.  Bands northwest of the center consisted mainly of showers and low clouds.  Storms near the core of the circulation generated upper level divergence which was pumping mass away to the east of the tropical cyclone.

Tropical Cyclone Iris will move through an environment somewhat favorable for intensification on Monday.  Iris will move over water where the Sea Surface Temperature is 29°C.  It is moving around the western end of an upper level ridge.  The ridge is producing northwesterly winds which were blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear and they may have been the reason for the lack of strong rainbands northwest of the center of circulation.  The wind shear is likely to inhibit intensification, but it probably won’t prevent Tropical Cyclone Iris from intensifying on Monday.

Tropical Cyclone Iris was moving around the western end of a subtropical ridge which was steering Iris toward the southwest.  Iris will likely move more toward the south and then southeast as it rounds the western end of the ridge.  On its anticipated track Tropical Cyclone Iris is expected to remain east of Queensland.

Elsewhere over the South Pacific Ocean Tropical Cyclone Josie was swirling south of Fiji.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Josie was located at latitude 21.1°S and longitude 178.1°E which put it about 185 miles (300 km) south of Suva, Fiji.  Josie was moving toward the south-southeast at 14 m.p.h. (22 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 999 mb.

Tropical Storm Jelawat Weakens Rapidly Over the Northern Marianas

Tropical Storm Jelawat weakened rapidly over the Northern Marianas on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Jelawat was located at latitude 19.3°N and longitude 145.5°E which put it about 50 miles (80 km) north-northwest of Agrihan.  Jelawat was moving toward the east-northeast at 14 m.p.h. (22 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 993 mb.

Former Typhoon Jelawat moved into an area where there were upper level westerly winds blowing at 50 m.p.h. (80 km/h).  Those strong upper level winds created enough vertical wind shear to blow the upper two thirds of the circulation east of the lower part of the circulation.  The remaining strong thunderstorms were weakening well to the east of the lower level circulation.  Tropical Storm Jelawat consisted primarily of narrow bands of showers and low clouds that were revolving around the center of circulation.  Jelawat may bring brief gusty winds and showers to the northernmost islands in the Marianas.

Tropical Cyclone Josie Brings Wind and Rain to Fiji

Tropical Cyclone Josie brought wind and rain to Fiji on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Cyclone Josie was located at latitude 19.2°S and longitude 177.4°E which put it about 105 miles (170 km) southwest of Suva, Fiji.  Josie was moving toward the east-southeast at 14 m.p.h. (22 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 998 mb.

Tropical Cyclone Josie formed within an area of thunderstorms that had persisted west of Fiji for several days.  A center of circulation developed within the area of thunderstorms and the Fiji Meteorological Service designated the system as Tropical Cyclone Josie.  The circulation of Tropical Cyclone Josie was somewhat asymmetrical.  Most of the stronger thunderstorms were occurring in the eastern half of the circulation.  The strongest winds were occurring in a primary rainband east of the center of circulation,  The bands in the western half of the circulation consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out about 160 miles (260 km) east of the center of circulation.

Tropical Cyclone Josie will move through an area somewhat favorable for intensification during the next day or two.  Josie will move over water where the Sea Surface Temperature is near 28°C.  It will move near an area where westerly winds are blowing in the upper levels and those winds may already be responsible for the asymmetrical distribution of stronger storms.  The upper level winds will cause moderate vertical wind shear, but the shear may not be strong enough to prevent some intensification.  Tropical Cyclone Josie could intensify slowly during the next 24 to 48 hours.

Tropical Cyclone Josie is moving near the eastern end of a ridge which is steering Josie toward the east-southeast.  The westerly winds in the middle troposphere will continue to steer Tropical Cyclone Josie toward the southeast during the next several days.  On its anticipated track the center of Josie will pass south of Viti Levu.  The center of Tropical Cyclone Josie will move near Kadavu and Ono in about 12 hours.  Even though the center of circulation will pass south of Viti Levu, Tropical Cyclone Josie will drop heavy rain there and the potential for flash floods will exist.  Josie will also bring gusty winds and heavy rain to Kadavu and Ono.

Typhoon Jelawat Rapidly Intensifies Into Equivalent of Major Hurricane

Typhoon Jelawat intensified rapidly on Friday into the equivalent of a major hurricane.  At 11:00 a.m. EDT on Friday the center of Typhoon Jelawat was located at latitude 17.1°N and longitude 139.5°E which put it about 440 miles (710 km) northwest of Guam.  Jelawat was moving toward the east-northeast at 13 m.p.h. (21 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 926 mb.

Typhoon Jelawat intensified rapidly on Friday.  There was a small circular eye at the center of circulation.  A ring of very strong storms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several spiral bands were revolving around the core of the circulation.  Storms near the core were generating well developed upper level divergence which was pumping large quantities of mass away to the east of the typhoon.  The removal of mass allowed the surface pressure to decrease rapidly and that produced a a rapid increase in wind speed.

Winds to typhoon force extend out about 45 miles (75 km) from the center of Typhoon Jelawat.  Winds to tropical storm force extend out about 175 miles (280 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Typhoon Jelawat is 31.6.  The Hurricane Size Index (HSI) is 17.7 and the Hurricane Wind Intensity Size Index (HWISI) is 49.3.

Typhoon Jelawat is in an environment favorable for strong typhoons, but it may be near its peak in intensity.  Jelawat will move over water where the Sea Surface Temperature is near 28°C.  Typhoon Jelwat has moved around the western end of an upper level ridge which is producing easterly winds that are blowing toward the top of the circulation.  The winds are causing some vertical wind shear, but the shear has not inhibited intensification.  When Typhoon Jelawat moves farther to the northeast it will move under stronger easterly and the wind shear will increase.  More shear will cause Jelawat to weaken during the next few days.

A subtropical ridge to the east of Typhoon Jelawat is steering the typhoon toward the east-northeast.  A general motion toward the east-northeast is expected to continue for several more days.  On its anticipated track Typhoon Jelawat could approach the northernmost islands in the Marianas in about 48 hours.

Typhoon Jelawat Strengthens West-Northwest of Guam

Former Tropical Storm Jelawat strengthened into a typhoon as it moved west-northwest of Guam on Thursday.  At 11:00 p.m. EDT on Thursday the center of Typhoon Jelawat was located at latitude 15.9°N and longitude 137.7°E which put it about 520 miles (840 km) west-northwest of Guam.  Jelawat was moving toward the east-northeast at 7 m.p.h. (11 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 972 mb.

Typhoon Jelawat strengthened quickly on Thursday night.  A small eye developed at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Typhoon Jelawat.  Storms in the core of the circulation were generating upper level divergence which was pumping mass away to the northeast of the typhoon.  Winds to typhoon force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 145 miles (230 km) from the center.

Typhoon Jelawat will move through an area favorable for intensification on Friday.  Jelawat will move over water where the Sea Surface Temperature is near 28°C.  Typhoon Jelawat has moved around the western end of an upper level ridge which is producing southwesterly winds which are blowing toward the top of the circulation.  Those winds are producing some vertical wind shear, but the wind shear is not strong enough to prevent intensification.   Typhoon Jelwat is likely to intensify further on Friday.

The upper level ridge is steering Typhoon Jelawat toward the east-northeast and that general motion is expected to continue for several more days.  On its anticipated track Typhoon Jelawat is expected to pass northwest of Guam.  Jelawat could approach the northernmost islands in the Marianas in about two or three days.

Tropical Storm Jelawat Strengthens West of Guam

Tropical Storm Jelawat strengthened west of Guam late on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Jelawat was located at latitude 12.3°N and longitude 135.5°E which put it about 230 miles (375 km) northwest of Yap and about 600 miles (970 km) west of Guam.  Jelawat was moving toward the north at 10 m.p.h. (16 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 994 mb.

After being affected by strong vertical wind shear for about 36 hours, Tropical Storm Jelawat began to strengthen late on Tuesday.  Many more thunderstorms formed near the center of circulation.  The circulation became much more symmetrical.  Bands of showers and thunderstorms formed in all parts of the circulation.  The storms near the center of circulation started to generate upper level divergence which pumped mass away from the tropical storm.

Tropical Storm Jelawat will be moving through an environment favorable for intensification during the next several days.  Jelawat will move over water where the Sea Surface Temperature is near 28°C.  Tropical Storm Jelawat is moving around the western end of an upper level ridge.  The ridge is producing southerly winds which are blowing toward the tropical storm.  The winds are producing some vertical wind shear, but the shear is not as strong as it has been.  Tropical Storm Jelawat will intensify during the next day or two and it could strengthen into a typhoon.

The ridge is steering Tropical Storm Jelawat toward the north and the northerly motion is expected to continue for another 12 to 24 hours.  Jelawat will move more toward the northeast in a day or so after it rounds the western end of the ridge.  On its anticipated track Tropical Storm Jelawat will move away from Yap and it will remain west of Guam.

Tropical Storm Jelawat Forms Near Yap

Tropical Storm Jelawat formed near Yap on Sunday.  At 2:00 p.m. EDT on Sunday the center of Tropical Storm Jelawat was located at latitude 7.6°N and longitude 138.4°E which put it about 120 miles (195 km) south of Yap.  Jelawat was moving toward the northwest at 14 m.p.h. (22 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 998 mb.

A low level center of circulation formed near the eastern edge of a cluster of thunderstorms near Yap on Sunday and the Japan Meteorological Agency designated the system as Tropical Storm Jelawat.  Tropical Storm Jelawat does not have a well organized circulation.  There is a distinct low level center of circulation, but most of the stronger thunderstorms are occurring west of the center of circulation.  The bands in the eastern half of the circulation consist mainly of showers and low clouds.  An upper level ridge over the Central North Pacific Ocean is producing strong easterly winds which are blowing across the top of the circulation.  Those winds are generating strong vertical wind shear and the shear is the main reason for the asymmetrical distribution of storms.

Tropical Storm Jelawat will be moving through an environment that is somewhat favorable for intensification.  Jelawat will move over water where the Sea Surface Temperature is near 28°C.  However, the upper level ridge will continue to cause vertical wind shear.  If the shear is not too strong and the circulation remains vertically coherent, then Tropical Storm Jelawat could strengthen during the next several days.   Some models predict this scenario and forecast that Jelawat will intensify into a typhoon.  Alternatively, if the wind shear increases further, strong upper level winds could blow the upper half of the circulation away from the lower level circulation.  If that occurs, Tropical Storm Jelawat will weaken.

The ridge over the Central North Pacific is steering Tropical Storm Jelawat toward the northwest.  Jelawat will reach the western end of the ridge in 12 to 24 hours.  The tropical storm will turn more toward the north when it reaches the end of the ridge.  On its anticipated track the center of Tropical Storm Jelawat is forecast to pass between Yap and Palau.