Monthly Archives: April 2018

Tropical Cyclone Flamboyan Forms East of Diego Garcia

Tropical Cyclone Flamboyan formed over the South Indian Ocean east of Diego Garcia on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Cyclone Garcia was located at latitude 10.6°S and longitude 89.2°E which put it about 1190 miles (1925 km) east-southeast of Diego Garcia.  Flamboyan was moving toward the west-southwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 995 mb.

A distinct low level center of circulation developed inside a large areas of showers and thunderstorms east of Diego Garcia on Saturday and the system was designated as Tropical Cyclone Flamboyan.  The circulation of Tropical Cyclone Flamboyan organized steadily during the day.  Several bands of showers and thunderstorms were revolving the core of the circulation.  Storms near the core were generating upper level divergence which was pumping away mass from the tropical cyclone in all directions.  Winds to tropical storm force extended out about 100 miles (160 km) from the center of circulation.

Tropical Cyclone Flamboyan will be moving through an environment favorable for intensification during the next day or two.  Flamboyan will move over water where the Sea Surface Temperature is near 28°C.  It is located under an upper level ridge and the upper level winds are weak.  Flamboyan will move through an area where there is little vertical wind shear.  Warm water and little shear will allow Tropical Cyclone Flamboyan to intensify and it could strengthen into the equivalent of a hurricane/typhoon.

Tropical Cyclone Flamboyan is moving around the western end of a subtropical ridge, which is steering the tropical cyclone toward the west-southwest.  Flamboyan will turn more toward the south when it rounds the western end of the ridge.  On its anticipated track Tropical Cyclone Flamboyan will move farther away from Cocos Island and it will pass well southeast of Diego Garcia.

Tropical Cyclone Fakir Brings Wind and Rain to Mauritius and La Reunion

Tropical Cyclone Fakir brought wind and rain to Mauritius and La Reunion on Tuesday.  At 5:00 a.m. EDT on Tuesday the center of Tropical Cyclone Fakir was located at latitude 21.9°S and longitude 56.6°E which put it about 80 miles (130 km) southeast of St. Denis, La Reunion.  Fakir was moving toward the southeast at 25 m.p.h. (40 km/h).  The maximum sustained wind 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 983 mb.  Fakir was the equivalent of a hurricane/typhoon.

The center of Tropical Cyclone Fakir passed between Mauritius and La Reunion on Tuesday and it brought gusty winds and heavy rain.  An eye formed at the center of circulation and a narrow ring of thunderstorms wrapped tightly around the eye.  The strongest winds were occurring in the ring of storms.  Bands of showers and thunderstorms were occurring south and east of the center of circulation.  The bands north and west of the center consisted primarily of light showers and low clouds.  Winds to tropical storm force extended out about 170 miles (270 km) from the center.

Tropical Cyclone Fakir was capable of causing minor wind damage on Mauritius and La Reunion.  Fakir was also dropping heavy rain and the rain was likely to produce flash floods in some locations.  Tropical Cyclone Fakir was moving rapidly to the southeast.  So, conditions on Mauritius and La Reunion are likely to improve later on Tuesday when the core of Fakir moves away.  Fakir has peaked in intensity.  Although it is moving over water where the Sea Surface Temperature is near 27°C, Tropical Cyclone Fakir has moved under an area of strong upper level winds blowing from the northwest.  Those winds will cause strong vertical wind shear, which will weaken Fakir.

Tropical Cyclone Fakir Strengthens Rapidly Northwest of La Reunion

Tropical Cyclone Fakir strengthened rapidly northwest of La Reunion on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Cyclone Fakir was located at latitude 18.2°S and longitude 54.5°E which put it about 220 miles (355 km) north-northwest of St. Denis, La Reunion.  Fakir was moving toward the southeast at 22 m.p.h. (35 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 992 mb.

A center of circulation developed early Monday in an area of thunderstorms east of Madagascar and the system was designated as Tropical Cyclone Fakir.  The circulation organized quickly and in a few hours Fakir strengthened into the equivalent of a strong tropical storm.  A primary rainband wrapped around the southern and western sides of the center of circulation.  There were some indications of the potential development of an eye at the center.  Additional bands of showers and thunderstorms developed south and east of the core of Tropical Cyclone Fakir.  Storms in the core of Fakir generated strong upper level divergence which pumped away mass to the southeast of the circulation.  The removal of mass allowed the surface pressure to decrease quickly and the winds to increase in response to that decrease.  Winds to tropical storm force extended out about 100 miles (160 km) from the center of circulation.

Tropical Cyclone Fakir could remain in an environment favorable for intensification for another 12 to 18 hours.  Fakir will move over water where the Sea Surface Temperature is near 28°C.  So, there is sufficient energy in the upper ocean to support intensification.  Tropical Cyclone Fakir is moving around the southwestern portion of an upper level ridge located over the South Indian Ocean.  The ridge is producing northwesterly winds which were blowing toward the top of the circulation.  The winds were causing moderate vertical wind shear, but they were not strong enough to prevent Fakir from strengthening rapidly on Monday.  Tropical Cyclone Fakir could become the equivalent of a hurricane/typhoon during the next 12 to 18 hours.  Fakir will move under stronger upper level winds in a day or so and then it will start to weaken because of the stronger vertical wind shear.

The upper level ridge is steering Tropical Cyclone Fakir rapidly toward the southeast and that general motion is expected to continue for several more days.  On its anticipated track Tropical Cyclone Fakir will approach Mauritius and La Reunion in about 12 hours.  It could be nearly the equivalent of a hurricane/typhoon at that time.  Fakir will bring gusty winds and heavy rain to Mauritius and La Reunion.  Minor wind damage is possible.  Locally heavy rain could cause flash floods.  The most likely track takes the center of Tropical Cyclone Fakir between Mauritius and La Reunion.  The western side of the circulation is a little weaker than the eastern side is.  If Fakir follows that track, then the strongest wind and heaviest rain could affect Mauritius.  However, Fakir will also affect La Reunion.

Tropical Cyclone Keni Brings Winds and Rain to Fiji

Tropical Cyclone Keni brought wind and rain to Fiji on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone Keni was located at latitude 19.4°S and longitude 178.0°E which put it about 100 miles (160 km) west-southwest of Suva, Fiji.  Keni was moving toward the east-southeast at 21 m.p.h. (34 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 976 mb.

Tropical Cyclone Keni intensified rapidly on Monday into the equivalent of a hurricane/typhoon.  A primary rainband wrapped tightly around the center of circulation and a small eye formed at the center.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Other bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Keni.  The strongest bands were east and south of the center of circulation.  Storms in the core of Keni were generating upper level divergence which was pumping away mass to the east of the tropical cyclone.  Winds to hurricane/typhoon force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.

Tropical Cyclone Keni will remain in an environment favorable for intensification for about another 12 to 18 hours.  It will move over water where the Sea Surface Temperature is near 28°C.  Keni is moving under the southwestern portion of an upper level ridge which is producing northwesterly winds which blowing toward the top of the circulation.  Those winds were causing some vertical wind shear, but the shear will not be strong enough to prevent intensification during the next few hours.  Tropical Cyclone Keni will move under strong upper level winds in about 12 to 18 hours and then the wind shear will increase.  Increased wind shear will cause Keni to start to weaken.

The ridge is steering Tropical Cyclone Keni toward the east-southeast and that general motion is expected to continue for another 12 to 18 hours.  An upper level trough approaching from the west will steer Keni more toward the southeast after that time.  On its anticipated track the core and strongest part of Tropical Cyclone Keni will pass southwest of Fiji.  However, clockwise flow around Keni will continue to cause gusty winds and drop heavy rain on Fiji.  The heavy rain could cause flash floods.  Keni could bring wind and rain to Tonga in 18 to 24 hours.

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.