Author Archives: jay_hobgood

Tropical Cyclone Niko Forms North of Tahiti

A small cluster of thunderstorms north of Tahiti organized rapidly on Tuesday and it has now been classified as Tropical Cyclone Niko.  At 7:00 p.m. EST on Tuesday the center of Tropical Cyclone Niko was centered at latitude 14.1°S and longitude 150.2°W which put it about 250 miles north-northwest of Papeete, Tahiti and about 220 miles northeast of Bora-Bora.  Niko was moving toward the south-southeast at 8 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there were gusts to 65 m.p.h.  The minimum surface pressure was estimated to be 989 mb.

The circulation around Niko is small and winds to tropical storm force only extend about 80 miles from the center.  The small circulation is in an area of lighter winds in the upper levels.  The modest wind shear allowed thunderstorms to develop rapidly around the center of circulation and Niko organized quickly during the past 12 hours.  Niko is currently over warm Sea Surface Temperatures and it is in an environment favorable for intensification.  Small tropical cyclones can intensify rapidly and Niko has the potential to do so during the next 24 hours.  It could reach typhoon intensity on Wednesday.

A combination of a near equatorial ridge and a subtropical ridge are steering Niko in a south-southeasterly direction and this general motion is expected to continue.  The projected path takes the center of Niko east of Tahiti.  However, it could move near some smaller islands including Mataiva, Makate, and Tikehau.  Given the small size of the circulation, the area of damage is likely to be limited, but any place getting hit directly by the center of circulation could see wind damage.

 

Tropical Storm Mekkhala Moving Through the Philippines

Tropical Storm Mekkhala is moving through the northern Philippines.  At 11:00 p.m. EST on Saturday the center of Tropical Storm Mekkhala was located at latitude 13.9°N and longitude 123.0°E which put it near Daet and about 150 miles east-southeast of Manilla.  Mekkhala was moving toward the northwest at 11 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 996 mb.

Mekkhala crossed over northern parts of Samar on Saturday and the center is near the southeastern portion of Luzon.  The islands disrupted parts of the circulation in the lower levels and Mekkhala weakened throughout the day.  Thunderstorms have been redeveloping in the part of the circulation over Lamon Bay and Mekkhala continues to be a tropical storm.  Divergence continues in the upper portion of the circulation and the wind shear remains at a moderate level.  While the atmospheric and oceanic environment would support intensification, if the center moves across Luzon further weakening is likely.

Mekkhala is near the western end of a subtropical ridge which has been steering the system toward the northwest.  If deep convection continues, then the ridge could continue to steer it toward the northwest.  However, if the system weakens to the point where only shallow convection exists, then it could be steered more toward the west by the lower level flow.

The relatively slow movement of Mekkhala continues the potential for locally heavy rainfall, flooding and mudslides.

 

Mekkhala Becomes a Typhoon As It Near the Philippines

Tropical Storm Mekkhala intensified rapidly on Friday and it has reached typhoon intensity.  At 3:00 p.m. EST on Friday the center of Mekkhala was located at latitude 10.9°N and longitude 127.5°E which put it about 280 miles east of Tacloban and about 500 miles east-southeast of Manila, Philippines.  Mekkhala was moving toward the west-southwest at 11 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and there were wind gusts to 90 m.p.h.  The minimum surface pressure was 974 mb.

The speed of the upper level east-southeasterly winds blowing over the top of Mekkhala weakened on Friday and the vertical shear affecting the circulation decreased.  The combination of less vertical wind shear and warm Sea Surface Temperatures allowed convection to develop all around the core of the circulation.  Strong thunderstorms near the center of Mekkhala created upper level divergence and the storm intensified rapidly into a typhoon.  Mekkhala remains in a favorable environment and further intensification is possible before it reaches the Philippines.  Once the center of circulation beings to move over the islands, interaction with land will weaken it.

A strengthening subtropical ridge has been steering Mekkhala a little south of due west and that motion is expected to continue in the short term.  The typhoon could reach the Philippines in about 12 hours.  Mekkhala could turn more toward the west-northwest as it crosses the Philippines and reaches the western end of the subtropical ridge.

Since Mekkhala has intensified into a typhoon the potential risks now include wind damage, and storm surge in addition to locally heavy rainfall, flooding and mudslides.

 

Tropical Cyclone Chedza Crossing Madagascar

Tropical Cyclone Chedza is moving across the central portion of Madagascar.  At 3:00 p.m. EST the center of Chedza was located at latitude 20.4°N and longitude 44.7°E which put it near Belo Tsiribihina.  It was moving toward the east-southeast at 10 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 55 m.p.h.  The minimum surface pressure was 996 mb.

Low vertical wind shear and warm Sea Surface Temperatures created an environment favorable for intensification and Chedza strengthened prior to making landfall in western Madagascar.  Satellite imagery indicated an eyelike feature formed and it is possible that Chedza may have reached hurricane intensity before landfall.  The terrain of Madagascar is weakening the lower portions of the circulation and that trend should continue while the center is over land.  It is possible that Chedza could strengthen after the center moves back over water east of Madagascar.

Tropical Storm Chedza Forms West of Madagascar

The tropical cyclone closest to land is Tropical Cyclone Chedza.  A cluster of thunderstorms meandering over the Mozambique Channel organized rapidly on Thursday and developed into Tropical Cyclone Chedza.  At 9:00 p.m. EST on Thursday the center of Chedza was located at latitude 19.1°S and longitude 42.4°E which put it about 140 miles west-northwest of Belo Tsiribihina, Madagascar.  It was moving toward the east at 6 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 55 m.p.h.  The minimum surface pressure was 996 mb.

Chedza is over warm Sea Surface Temperatures and the upper level winds are relatively light.  Further intensification is likely until Chedza makes landfall on Friday.  It is expected to weaken as it crosses Madagascar.  Some re-intensification may be possible after the center emerges over the Indian Ocean east of Madagascar.  Potential risks include locally heavy rainfall and flooding.

A near equatorial ridge is steering Chedza eastward.  It is expected to make landfall in 12 to 18 hours.  The ridge is expected to steer Chedza toward the east-southeast as it crosses Madagascar.

 

Tropical Storm Mekkhala Intensifies Slightly As It Moves Toward the Philippines

At 9:00 p.m. EST on Thursday the center of Tropical Storm Mekkhala was located at 11.6°N and longitude 131.1°E which put it about 540 miles east of Tacloban and about 710 miles east-southeast of Manila, Philippines.  Mekkhala was moving toward the west at 9 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.

East-southeasterly winds in the upper levels continue to cause moderate wind shear over the top of Mekkhala.  It has a well developed low level circulation, but most of the thunderstorm formation is still in the western half of the storm.  Although Mekkhala is over warm Sea Surface Temperatures, the wind shear is inhibiting intensification.  Further intensification is possible, but it will likely be limited.

A subtropical ridge north of Mekkhala is extending westward and the ridge should continue to steer it westward.  The projected path would bring Mekkhala near the central Philippines in 24 to 36 hours.  Potential risks include locally heavy rain, flooding and mudslides.

 

Tropical Cyclone Bansi Moving Away from Mauritius

At 9:00 p.m. EST on Thursday the center of Tropical Cyclone Bansi was located at latitude 19.0°S and longitude 64.1°E which put it about 385 miles east-northeast of Port Louis, Mauritius.  Bansi was moving toward the east-southeast at 12 m.p.h.  The maximum sustained wind speed was 130 m.p.h. and it was estimated there were wind gusts to 160 m.p.h..  The minimum surface pressure was estimated to be 937 mb.

Bansi was in an environment of low vertical wind shear and warm Sea Surface Temperatures for much of Thursday and intensified slightly.  The speed of the upper level winds is increasing and the cloud pattern is showing signs of more wind shear.  A subtropical high pressure system is likely to move Bansi toward the southeast at a faster speed.  Bansi is likely to continue to move toward higher latitudes which will move it over colder water.  The speed of the upper level winds will also increase and so Bansi should weaken during the next few days.

 

Tropical Storm Mekkhala Develops East of the Philippines

Tropical Depression 01W intensified into Tropical Storm Mekkhala on Wednesday.  At 11:00 p.m. EST on Wednesday the center of Tropical Storm Mekkhala was located at latitude 11.5°N and longitude 133.8°E which put it about 370 miles north-northwest of Palau and about 820 miles east of Manila, Philippines.  Mekkhala was moving toward the west at 16 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were gusts to 60 m.p.h.   The minimum surface pressure was 1000 mb.

Although there are still moderate wind speeds in the upper levels, the wind shear decreased slightly.  That allowed more thunderstorms to develop closer to the center of circulation and the system became more organized.  A subtropical ridge northeast of Mekkhala will continue to produce southeasterly winds over the top of the circulation.  Moderate wind shear will limit intensification.  However, Mekkhala will be moving over Warm Sea Surface Temperatures and so some intensification is possible during the next several days.

The subtropical ridge is expected to strengthen and steer Mekkhala westward toward the Philippines.  The tropical storm could be approaching the central and northern Philippines in 48 to 72 hours.  The main threats appear to be locally heavy rainfall, flooding and mudslides.

 

Tropical Cyclone Bansi Maintaining Intensity Northeast of Mauritius

At 11:00 p.m. EST on Wednesday the center of Tropical Cyclone Bansi was located at latitude 17.6°S and longitude 60.3°E which put it about 270 miles northeast of Port Louis, Mauritius.  Bansi was moving toward the east-southeast at 8 m.p.h.  The maximum sustained wind was 105 m.p.h. and it was estimated there were wind gusts to 125 m.p.h.  The minimum surface pressure was estimated to be 954 mb.

An eyewall replacement cycle altered the structure of Tropical Cyclone Bansi.  It previously had a small eye which had a diameter of 10-15 miles.  The outer eyewall has not contracted significantly since the inner eye dissipated.  Thus, Bansi is now a tropical cyclone with a large circular eye with a diameter of about 60 miles.  The circulation around Bansi seems to have achieved a rough equilibrium  with its surrounding environment and the intensity did not change much on Wednesday.  Bansi remains over warm Sea Surface Temperatures and in an area of light upper level winds.  So, it is still possible that some intensification could occur in the short term.  When Bansi moves to a higher latitude it will encounter cooler water and more wind shear and start to weaken.

A subtropical ridge near Bansi is expected to start to exert a greater influence and start to accelerate it toward the southeast at a faster speed in about 24 hours.

 

Tropical Depression 01W Forms East of Yap

The first tropical depression of 2015 over the Western North Pacific Ocean formed east of Yap on Tuesday.  At 7:00 p.m. EST on Tuesday the center of Tropical Depression 01W (TD01W) was located at latitude 10.1°N and longitude 139.9°E which put it about 130 miles east-northeast of Yap and about 1250 miles east-southeast of Manila, Philippines.  TD01W was moving toward the northwest at 13 m.p.h.  The maximum sustained wind speed was 35 m.p.h. and there were gusts to 45 m.p.h.  The minimum surface pressure was estimated to be 1000 mb.

A subtropical ridge is generating southeasterly winds over the top of TD01W and producing moderate wind shear.  The wind shear is causing much of the thunderstorm activity to be located in the northwestern part of the circulation around TD01W.  The lack of thunderstorms in the southern portion of the circulation is limiting the intensification of the tropical depression.  TD01W is over Sea Surface Temperatures that are around 30°C and so the potential for intensification exists if the speed of the upper level winds diminish.

The subtropical ridge is expected to continue to steer the tropical depression in a general west or west-northwesterly direction during the next few days.  This projected path could bring the tropical cyclone near the Philippines later this week.