Monthly Archives: December 2014

Jangmi Weakens over Sulu Sea

Increased vertical wind shear blew the tops off of thunderstorms and Tropical Storm Jangmi weakened to a tropical depression,  At 11:00 p.m. EST on Tuesday the center of Tropical Depression Jangmi was located at latitude 8.0°N and longitude 120.8°E which put it about 150 miles north of Jolo, Philippines and about 300 miles east-northeast of Kudat, Malaysia on the northern end of Borneo.  Jangmi was moving toward the west-southwest at 7 m.p.h.  The maximum sustained wind speed was 30 m.p.h. and there were gusts to 40 m.p.h.

A subtropical ridge north of Jangmi intensified southeasterly winds in the upper levels and increased the wind shear over the top of the tropical storm.  The stronger upper level winds blew away the upper portions of thunderstorms and the circulation contained mainly shallower convection during the most recent 12 hours.  Recent satellite images show the redevelopment of some thunderstorms southwest of the center of circulation, but some wind shear continues.  Jangmi is over Sea Surface Temperatures that are warm enough to support some intensification, but that will not happen if the wind shear continues.  If Jangmi continues to move southwestward, interaction with the island of Borneo could weaken the circulation and possibly cause it to dissipate entirely.  If the center passes just west of Borneo, then some intensification may be possible, unless the wind shear remains too strong.

Since the circulation of Jangmi consisted mainly of shallower convection, it was steered toward the southwest by northeasterly winds in the lower levels of the atmosphere.  Even though a few thunderstorms have redeveloped, most of the convection is still shallow and Jangmi is likely to continue to be steered in a generally west-southwesterly direction.  The projected track could bring Jangmi or its remnants near the northern end of Borneo in 24-48 hours.

 

 

Tropical Storm Jangmi Moving across the Sulu Sea

Tropical Storm Jangmi moved across Mindanao and the center passed near Cebu.  It has now moved back over the open waters of the Sulu Sea.  At 11:00 p.m. EST on Monday the center of Tropical Storm Jangmi was located at latitude 10.4°N and longitude 121.0°E which put it about 320 miles south of Manila, about 200 miles east-northeast of Puerto Princesa and about 1300 miles east-northeast of Singapore.  Jangmi was moving toward the west at 11 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.

Thunderstorms are beginning to redevelop near the center of circulation now that it has moved back over water.  The low level center appears to be relatively intact after its passage over some of the islands in the southern Philippines.  Easterly winds in the upper levels are generating some wind shear, but there is well developed upper level outflow on the northern side of Jangmi.  It will be moving over warm Sea Surface Temperatures and some intensification is possible as it moves westward.

Jangmi is being steered to the west by a subtropical ridge located to its north.  The general westward motion is expected to continue in the short term.  Eventually, northeasterly winds are expected to push Jangmi in a more west-southwesterly direction over the next few days.  The projected track is expected to take the center across Palawan near Puerto Princesa in about 24 hours.  The west-southwesterly motion is expected to continue and it could take Jangmi in the general direction of Malaysia.

Jangmi could bring some locally heavy rainfall to parts of Palawan and some flooding and landslides are possible.

 

Tropical Storm Jangmi Develops Near the Southern Philippines

A well developed center of circulation formed in an area of thunderstorms near the island of Mindanao and the system has been classified as Tropical Storm Jangmi.  At 10:00 p.m. EST on Sunday the center of Tropical Storm Jangmi was located at latitude 8.8°N and longitude 126.0°E, which put it near the city of Prosperidad on Mindanao.  The center of Jangmi was located about 200 miles east-southeast of Cebu, about 500 miles east of Puerto Princesa and about 1550 miles east-northeast of Singapore.  Jangmi was moving toward the west-northwest at 10 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.

The atmospheric environment around Jangmi is generally favorable for intensification.  Easterly winds in the upper levels are causing some wind shear, and there is more convection on the western side of the storm.  However, upper level divergence is very well developed on the northern side of the circulation and the circulation is pumping out mass.  The center of circulation was organizing rapidly as Jangmi neared Mindanao and there was some evidence of an eye forming.  The center has now moved over Mindanao and movement over land will disrupt the circulation in the short term and it should limit the potential for intensification during the next 24 hours.  Sea Surface Temperatures around the southern Philippines are warm and Jangmi could intensify when it moves west of Mindanao.  The tropical storm will encounter cooler and drier air after it moves west of the Philippines.

Jangmi is being steered in a general west to west-northwesterly direction by a subtropical ridge to it north.  It is expected to continue in that general direction during the next day or two.  When Jangmi moves west of the Philippines it will encounter stronger northeasterly winds in the lower levels of the atmosphere.  Those winds could push Jangmi more toward the west-southwest later this week.

The relatively slow movement of Jangmi could create the potential for locally heavy rainfall over portions of the southern Philippines.  In places where the heaviest rain falls, it could create the conditions to produce some flooding and landslides.

 

Tropical Cyclone Kate Intensfies Rapidly over Southeastern Indian Ocean

Favorable oceanic and atmospheric conditions allowed Tropical Cyclone Kate to intensify very rapidly on Friday.  The maximum sustained wind speed increased from 50 m.p.h. to 120 m.p.h. during a 24 hour period.  At 10:00 p.m. EST on Friday the center of Tropical Cyclone Kate was located at latitude 12.9°S and longitude 93.8°E which put it about 215 miles west-southwest of the Cocos Islands and about 2450 miles west of Darwin, Australia.  Kate was moving toward the southwest at 5 m.p.h., which was taking it away from the Cocos Islands.  The maximum sustained wind speed was 120 m.p.h. which made Kate the equivalent of a Category 3 hurricane on the Saffir-Simpson Scale and it was estimated that there were gusts to 150 m.p.h.

Although there were upper level winds blowing from the east, which created some wind shear over Kate, it was able to develop strong upper level outflow which produced rapid intensification.  Some satellite imagery shows that the wind shear is causing the strongest thunderstorms to be on the western side of the center of circulation.  Recent visible and infrared satellite imagery show evidence of an circular eye developing.  Some further intensification is possible during the next 24 hours as long as the upper level outflow is able to pump out sufficient mass.  Eventually, as Kate moves toward higher latitudes the wind shear will increase and the Sea Surface Temperatures will decrease.  The more hostile environment will weaken the tropical cyclone and the weakening could be almost as rapid as the intensification was.

Kate is expected to continue to be steered in a generally southwesterly direction in the short term by a subtropical ridge.  As it moves farther south, it will begin to be affected by westerly midlatitude flow and it will start to recurve more toward the south.  Kate passed over the Cocos Islands earlier this week as a tropical storm.  It is expected to dissipate over the Indian Ocean and not affect any other land areas as a tropical cyclone.

 

Hagupit a Tropical Storm for One More Day

Thunderstorms continue to develop intermittently near the center of Hagupit and it is producing enough deep convection to maintain its status as a tropical storm.  At 10:00 p.m. EST on Wednesday the center of Tropical Storm Hagupit was located at latitude 13.2°N and longitude 113.1°E which put it about 275 miles east-northeast of Cam Ranh, Vietnam and about 460 miles east-northeast of Ho Chi Minh City.  Hagupit was moving toward the west-southwest at 9 m.p.h.  The maximum sustained wind speed was 40 m.p.h.  and there were gusts to 50 m.p.h.

Although Hagupit is moving over warm Sea Surface Temperatures, the rest of the environmental factors are unfavorable for intensification.  Northeasterly winds over the South China Sea are transporting cooler and drier air, which is wrapping around the western and southern parts of Hagupit’s circulation.  There is also significant vertical wind shear, which is tilting the circulation.  The tight low level center of circulation is producing enough convergence to continue generating some new thunderstorms near the center, but the convection is becoming more intermittent.  Hagupit is likely to slowly weaken during the next 24 hours as a result of the mainly hostile environment around it.

The northeasterly winds are likely to push Hagupit toward the west-southwest or southwest during the next 24 hours.  The projected track would bring Hagupit to the coast of Vietnam near Cam Ranh in about 24 hours.  It is likely to have minimal impact when it makes landfall.  There could be a period of gustier winds and an increase in rainfall, but Hagupit could dissipate fairly quickly as it moves inland.

 

Tropical Storm Hagupit Maintaining Its Intensity for Now

Tropical Storm Hagupit maintained its intensity on Tuesday as it moved farther away from the Philippines.  At 10:00 p.m. EST on Tuesday the center of Tropical Storm Hagupit was located at latitude 13.3°N and longitude 116.6°E which put it about 320 miles west-southwest of Manila, Philippines and about 475 miles east-northeast of Cam Ranh, Vietnam.  Hagupit was moving toward the west at 13 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there gusts to 65 m.p.h.

Thunderstorms continue to develop near the center of circulation and upper level outflow is evident on satellite images.  However, Hagupit is likely to move into a more unfavorable environment as it moves westward.  Northeasterly winds over the lower levels of the South China Sea contain cooler and drier air.  Some of the cooler, drier air may be getting pulled around the western and southern portions of Hagupit’s circulation.  If the drier air reaches the center of circulation, then deep convection will diminish and the wind speeds will decrease.  Hagupit is also likely to move into an area of more vertical wind shear as it moves westward, which could weaken the storm even faster.

Hagupit is currently being steered westward by a subtropical ridge located north of it.  If Hagupit weakens and the convection becomes shallower, if could be steered toward the southwest or west-southwest by the northeasterly winds in the lower levels.  The center of Hagupit could near the coast of Vietnam in about 36 hours.

 

Tropical Storm Hagupit Moving Away From the Philippines

Tropical Storm Hagupit has moved across the central Philippines and it is now beginning to move into the South China Sea.  At 10:00 p.m. EST on Monday the center of Tropical Storm Hagupit was located at latitude 13.5°N and longitude 119.9°E which put it about 100 miles southwest of Manila.  Hagupit was moving toward the southwest at 11 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.

Some thunderstorms have redeveloped near the center of Hagupit now that it is back out over open water.  It is possible that the tropical storm could maintain its intensity or even strengthen a little in the short term.  However, as Hagupit moves farther west it will encounter a northeasterly flow of cooler and drier air and more pronounced vertical wind shear.  The more unfavorable thermodynamic environment and wind shear will likely cause Hagupit to weaken during the next few days.

The northeasterly winds are expected to push a weakening tropical storm or depression in the general direction of southern Vietnam.  Hagupit or its remnants could make landfall in Vietnam in about 72 hours.

 

Hagupit Weakening As It Moves Across the Philippines

Hagupit has weakened below typhoon intensity and it is now a tropical storm.  At 10:00 p.m. EST on Sunday the center of Tropical Storm Hagupit was located at latitude 13.4°N and longitude 112.7°E which put it near Catanauan, Philippines and about 140 miles southeast of Manila.  Hagupit was moving toward the northwest at 7 m.p.h.  The maximum sustained wind speed was 70 m.p.h. and there were gusts to 85 m.p.h.

Interaction of the circulation with land and moderate vertical wind shear have gradually reduced the intensity of Hagupit and the weakening trend should continue on Monday.  Once Hagupit moves west of the Philippines, it will move into an area of stronger northeasterly winds in the lower levels and cooler, drier air.  As a result the rate of weakening could increase.

There are indications that Hagupit could begin to move toward the southwest when it encounters the stronger northeasterly flow.  A much weaker Hagupit or its remnants could reach southern Vietnam in a few days.

 

Typhoon Hagupit Is Crossing the Central Philippines

Typhoon Hagupit made a landfall near Dolores on the east coast of the island of Samar in the Philippines on Saturday.  It brought strong winds and heavy rain to parts of Samar.  At 10:00 p.m. EST on Saturday the center of Typhoon Hagupit was located at latitude 11.8°N and longitude 124.3°E which put it near Masbate in the central Philippines and about 300 miles southeast of Manila.  Hagupit was moving toward the west at 8 m.p.h.  The maximum sustained wind speed was 105 m.p.h. and there were gusts to 125 m.p.h.

Hagupit was being steered to the west by a subtropical ridge to the north of the typhoon.  The subtropical ridge is expected to steer it in a generally west or west-northwesterly direction during the next day or two.  A surge of northeasterly winds could steer Hagupit to the southwest after it begins to move west of the Philippines.

The interaction of the circulation around Hagupit with the islands and topography of the central Philippines is expected to continue to weaken the typhoon.  It could bring strong winds and locally heavy rainfall to southern Luzon and Mindoro as it moves across those areas.  Heavy rains could create a potential for flooding and mudslides in some areas.  Hagupit could still be a typhoon when it moves south of Manila in 24 to 36 hours.

 

Super Typhoon Hagupit Approaching the Philippines

Super Typhoon Hagupit is nearing the Philippines and the center will pass near the northern end of Samar during the next 24 hours.  At 7:00 p.m. EST on Friday the center of Hagupit was located at latitude 12.3°N and longitude 127.4ºE which put it about 240 miles east of Legaspi, Philippines and about 450 miles east-southeast of Manila.  Hagupit was moving toward the west-northwest at 7 m.p.h.  The maximum sustained wind speed was 150 m.p.h. and there were gust estimated to 185 m.p.h.

The intensity of Hagupit has fluctuated during the past 24 hours as the speed of the upper level winds has varied and the internal dynamics of the circulation have affected the wind speed. The Sea Surface Temperatures near the Philippines are just slightly cooler and interaction with the islands will cause some disruption to the circulation.  As a result, Hagupit will most likely maintain its intensity or slowly weaken as it approaches the Philippines.  If the circulation interacts more with the islands, then the rate of weakening will be faster.

Hagupit continues to be steered to the west-northwest by a subtropical ridge to its north and that steering pattern appears likely to continue.  On its current path, Hagupit will begin to affect portions of the Central Philippines on Saturday.  Hagupit will move near the northern end of Samar and then begin to have an impact on southeastern and southern Luzon.  The center of Hagupit could be near Manila in about 72 hours.  Hagupit will be weaker, but it could still be a typhoon when it approaches Manila.

Hagupit will bring strong winds and heavy rainfall as it crosses the central Philippines.  The Hurricane Intensity Index for Hagupit is 25.1 and the Hurricane Size Index is 19.9  which means that it has the potential to cause regional significant damage.  Heavy rain will create the potential for flooding and mudslides.  Some locations could also see a significant storm surge.