Former Tropical Depression 05W strengthened to Tropical Storm Hagupit over the Western North Pacific Ocean south of the Marianas on Tuesday night. At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Hagupit was located at latitude 7.4°N and longitude 146.5°E which put the center about 435 miles (705 km) south-southeast of Guam. Hagupit was moving toward the west at 7 m.p.h. (11 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 1003 mb.
Former Tropical Depression 05W strengthened on Tuesday night and the Japan Meteorological Agency designated the system as Tropical Storm Hagupit.
Thunderstorms continued to develop near the center of Tropical Storm Hagupit. However, the distribution of thunderstorms around the rest of Hagupit’s circulation became a little more asymmetrical during the past 12 hours. Thunderstorms were still occurring in bands in the eastern side of Tropical Storm Hagupit. Bands in the western side of Hagupit’s circulation consisted primarily of showers and lower clouds. Storms near the center of Hagupit generated some upper level divergence that pumped mass away from the tropical storm. The removal of mass in the upper levels was nearly matched by the inflow of mass in the lower levels of the atmosphere. So, the surface pressure was not changing much.
The distribution of wind speeds in Tropical Storm Hagupit was also asymmetrical. Winds to tropical storm force extended out 100 miles (160 km) in the northeastern quadrant of Hagupit’s circulation. The winds in the other parts of Tropical Storm Hagupit were blowing at less than tropical storm force.
Tropical Storm Hagupit will move through an environment favorable for intensification during the next 24 hours. Hagupit will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge that is over the Western North Pacific Ocean. The upper level ridge will produce easterly winds that will blow toward the top of Hagupit’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification. Tropical Storm Hagupit will intensify slowly during the next 24 hours. Hagupit could strengthen to a typhoon later this week.
Tropical Storm Hagupit will move around the southern side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Hagupit toward the west during the next 24 hours. On its anticipated track, Tropical Storm Hagupit will pass south of Guam. Hagupit could approach Yap in 48 hours. Hagupit will likely be a tropical storm when it approaches Yap.