Tag Archives: WP93

Tropical Depression Forms East of Luzon

A tropical depression formed over the Western North Pacific Ocean east of Luzon on Sunday morning. At 5:00 a.m. EDT on Sunday the center of the tropical depression was located at latitude 17.4°N and longitude 127.3°E which put it about 350 miles (565 km) east of Luzon. The tropical depression was moving toward the west at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1000 mb.

A distinct low level center of circulation formed in an area of lower pressure east of Luzon on Sunday morning and the Japan Meteorological Agency classified the system as a tropical depression. The distribution of thunderstorms in the tropical depression was asymmetrical. Most of the thunderstorms were in bands in the western half of the tropical depression. The bands in the eastern half of the circulation consisted primarily of showers and lower clouds. A strong upper level ridge over China was producing strong northeasterly winds that were blowing toward the top of the tropical depression. Those winds were causing moderate vertical wind shear and the wind shear was causing the asymmetrical distribution of thunderstorms.

The tropical depression will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over water where the Sea Surface Temperatures are 30˚C. The upper level ridge over China will continue to produce northeasterly winds that will blow toward the top of the tropical depression. However, the upper level winds are forecast to weaken. The vertical wind shear could decrease during the next 24 hours. The tropical depression is forecast to strengthen to a tropical storm.

The tropical depression will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer the tropical depression toward the west during the next 24 hours. On its anticipated track the tropical depression could approach northeastern Luzon in 24 hours. It is likely to be a tropical storm when it approaches Luzon. The weather system will bring gusty winds and locally heavy rain to northern Luzon. Heavy rain could cause flash floods in some locations.

Tropical Storm Songda Develops East of Okinawa

Tropical Storm Songda developed east of Okinawa on Thursday afternoon. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Songda was located at latitude 26.4°N and longitude 136.6°E which put it about 600 miles (970 km) east of Okinawa. Songda was moving toward the north-northwest at 29 m.p.h. (45 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1002 mb.

An area of low pressure strengthened east of Okinawa on Thursday afternoon and the Japan Meteorological Agency designated the system as Tropical Storm Songda. Tropical Storm Songda was revolving around the northeastern part of a much larger low pressure system (sometimes called a monsoon gyre) centered northeast of the Philippines. The interaction of Songda’s circulation with the larger low pressure system was producing an asymmetrical distribution of thunderstorms. Thunderstorms were occurring in bands in the northeastern half of Tropical Storm Songda. Bands in the southwestern half of Songda consisted primarily of showers and lower clouds. Storms near the center of Songda generated upper level divergence that pumped mass away to the northeast of the tropical storm.

Tropical Storm Songda will move through an environment marginally favorable for intensification during the next 24 hours. Songda will move over water where the Sea Surface Temperatures are near 30˚C. The circulation around the larger low pressure system will produce upper level winds from the southeast that will blow toward the top of Songda’s circulation. The winds in the lower levels of the atmosphere will also be blowing from the southeast and so there will be less vertical wind shear. The wind shear could still be strong enough to inhibit intensification. Songda could also move into a region where the air is drier. Tropical Storm Songda could strengthen a little during the next 24 hours, but wind shear and drier air are likely to limit intensification.

The large low pressure system northeast of the Philippines will steer Tropical Storm Songda toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Sondga could approach the northern Ryukyu Islands within 24 hours. Songda could bring gusty winds and locally heavy rain to the northern Ryukyu Islands.