Monthly Archives: February 2015

Typhoon Higos Maintaining Intensity Well East of Guam

The organization of Typhoon Higos improved on Monday.  At 11:00 p.m. EST on Monday the center of Typhoon Higos was located at latitude 13.7°N and longitude 154.7°E which put it about 710 miles east of Guam and about 870 miles west-southwest of Wake Island.  Higos was moving toward the northwest at 9 m.p.h.  The maximum sustained wind speed was 95 m.p.h. and there were gusts to 115 m.p.h.  The minimum surface pressure was 967 mb.

The circulation around Higos remains in an area where the upper level winds are not too strong and the wind shear is in the light to moderate range.  An eye has developed at the center of circulation which is evident on both infrared and visible satellite imagery.  The eye is surrounding by a tight symmetrical ring of thunderstorms.  It has the appearance of a well organized circulation.  Upper level outflow continues and it is especially strong on the northeast side of Higos.  The typhoon also remains over warm Sea Surface Temperatures and so the environment could support some further intensification on Tuesday.  As Higos moves farther north, it will begin to be affected by stronger upper level westerly winds.  The stronger winds will create more wind shear and weaken Higos.

Higos is moving around the western end of a subtropical ridge, which is steering it toward the northwest.  As it gets farther north, the upper level westerly winds will being to push it toward the northeast.  Higos is expected to weaken as it moves northwest of Wake Island.

 

Higos Intensfies Into a Typhoon

Tropical Storm Higos intensified into a typhoon on Sunday.  At 11:00 p.m. EST on Sunday the center of Typhoon Higos was located at latitude 12.3°N and longitude 156.4°E which put it about 780 miles east of Guam.  It was moving toward the west-northwest at 3 m.p.h.  The maximum sustained wind speed was 85 m.p.h. and there were gusts to 100 m.p.h.  The minimum surface pressure was 967 mb.

Higos has been moving slowly through an area where the vertical wind shear was not too strong.  Thunderstorms around the center of circulation supported strong upper level divergence, which pumped out large quantities of mass.  A well developed upper level outflow channel to the northeast enhanced the flow of mass away from the system.  Those processes allowed the surface pressure to decrease and the wind speeds to increase on Sunday.  Higos remains over warm Sea Surface Temperatures and further intensification is possible on Monday.  Eventually, when it moves farther north, Higos will move into an area of stronger wind shear and weaken.

Higos is moving near the western end of a subtropical ridge.  It is in an area of weak steering winds, and Higos is moving slowly.  The increased intensity and vertical height of the circulation make it more likely that Higos will move toward the north as it reaches the western end of the subtropical ridge.  The guidance from numerical models has increased the probability of this track.

 

Tropical Storm Higos Forms East of Guam

A center of circulation consolidated within a large area of thunderstorms centered about 900 miles east of Guam and the system was designated as Tropical Storm Higos.  At 10:00 p.m. EST on Saturday the center of Tropical Storm Higos was located at latitude 12.1°N and longitude 157.4°E which put it about 480 miles northeast of Fananu and about 850 miles east of Guam.  Higos was moving toward the north-northwest at 7 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were wind gusts to 60 m.p.h.  The minimum surface pressure was 993 mb.

Higos was moving over warm Sea Surface Temperatures.  Satellite imagery indicated that upper level divergence was well developed and there appeared to be an outflow channel to the northeast.  As the divergence pumped out mass, the surface pressure decreased and the wind speeds increased.  A spiral band of thunderstorms wrapped around the center of circulation and the system displayed increased organization.  Higos has the potential to intensify during the next 24 to 48 hours and it could possible become a typhoon.  Later in the week stronger upper level winds are expected to increase the vertical wind shear and weaken Higos.

Higos was near the western end of a subtropical ridge of high pressure which was steering it toward the northwest.  The subtropical ridge is expected to continue to steer the storm toward the northwest in the short term.  Over the longer term the track of Higos will depend to some extent on how strong it becomes.  If it intensifies more, Higos will be affected more strongly by upper level westerly winds located farther north.  Those winds would cause Higos to take a more northerly track.  If Higos remains weaker, then it could be less affected by the upper level westerlies and it might take a track farther south.  Guidance from numerical models is split between a more northerly and a more westerly track.

 

Tropical Cyclone Fundi Forms Near the Southwest Coast of Madagascar

A well defined center of circulation developed in the lower levels of an area of thunderstorms near the southwest coast of Madagascar and the system was designated as Tropical Cyclone Fundi.  At 5:00 p.m. EST on Friday the center of Tropical Cyclone Fundi was located at latitude 22.8°N and longitude 42.9°E which put it about 60 miles west of Toliara, Madagascar.  Fundi was moving toward the southeast at 8 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were gusts to 50 m.p.h.  The minimum surface pressure was 999 mb.

The environment around Fundi contains some factors that would support intensification and other factors that would inhibit intensification.  It is over warm Sea Surface Temperatures and there is well developed outflow in the upper levels.  Those factors would favor intensification.  However, the center of circulation is very close to the coast of Madagascar and part of the circulation is over land.  Interaction with land will inhibit future intensification.  If the center of circulation remains over the water, then some intensification is possible during the next day or two.  If the center of circulation moves over southern Madagascar, then it will weaken.  Eventually, Fundi will move poleward and encounter colder Sea Surface Temperatures and more vertical wind shear.

 

A subtropical ridge located east of Fundi is steering the tropical cyclone toward the southeast.  The ridge is expected to continue to steer it toward the southeast or south in the short term.  As Fundi moves farther south, it will begin to encounter upper level westerly winds which will turn it more toward the east.

Tropical Cyclone Ola Intensifying Northwest of New Caledonia

Tropical Cyclone Ola intensified rapidly on Saturday as it moved over the Coral Sea northwest of New Caledonia.  At 8:00 p.m. EST on Saturday the center of Ola was located at latitude 19.9°S and longitude 162.9°E which put it about 260 miles northwest of Noumea, New Caledonia.  Ola was moving toward the south-southeast at 8 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and there were gusts to 95 m.p.h.  The minimum surface pressure was 970 mb.

Ola is moving over warm Sea Surface Temperatures (SSTs) and the environmental winds are generating upper level divergence to the southeast of the circulation.  The divergence pumped out mass and surface pressure decreased rapidly.  As a result, Ola intensified into the equivalent of a hurricane on Saturday.  Ola will remain over warm SSTs, but it will move into an area of stronger upper level winds when it moves farther southward.  It could intensify more during the next 24 hours, but it is likely to begin to weaken in 36 to 48 hours because of increasing vertical wind shear.

Counterclockwise flow around the western end of a subtropical ridge is steering Ola in a general southward direction.  That motion is expected to continue for another 24 hours.  A ridge of high pressure is expected to build south of Ola in a day or so.  The ridge could block Ola from moving any farther toward the south and turn it toward the southwest.  On the expected track, Ola would stay west of New Caledonia.  It is expected to weaken before it reaches Australia.