Tropical Storm Jelawat Forms Near Yap

Tropical Storm Jelawat formed near Yap on Sunday.  At 2:00 p.m. EDT on Sunday the center of Tropical Storm Jelawat was located at latitude 7.6°N and longitude 138.4°E which put it about 120 miles (195 km) south of Yap.  Jelawat was moving toward the northwest at 14 m.p.h. (22 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 998 mb.

A low level center of circulation formed near the eastern edge of a cluster of thunderstorms near Yap on Sunday and the Japan Meteorological Agency designated the system as Tropical Storm Jelawat.  Tropical Storm Jelawat does not have a well organized circulation.  There is a distinct low level center of circulation, but most of the stronger thunderstorms are occurring west of the center of circulation.  The bands in the eastern half of the circulation consist mainly of showers and low clouds.  An upper level ridge over the Central North Pacific Ocean is producing strong easterly winds which are blowing across the top of the circulation.  Those winds are generating strong vertical wind shear and the shear is the main reason for the asymmetrical distribution of storms.

Tropical Storm Jelawat will be moving through an environment that is somewhat favorable for intensification.  Jelawat will move over water where the Sea Surface Temperature is near 28°C.  However, the upper level ridge will continue to cause vertical wind shear.  If the shear is not too strong and the circulation remains vertically coherent, then Tropical Storm Jelawat could strengthen during the next several days.   Some models predict this scenario and forecast that Jelawat will intensify into a typhoon.  Alternatively, if the wind shear increases further, strong upper level winds could blow the upper half of the circulation away from the lower level circulation.  If that occurs, Tropical Storm Jelawat will weaken.

The ridge over the Central North Pacific is steering Tropical Storm Jelawat toward the northwest.  Jelawat will reach the western end of the ridge in 12 to 24 hours.  The tropical storm will turn more toward the north when it reaches the end of the ridge.  On its anticipated track the center of Tropical Storm Jelawat is forecast to pass between Yap and Palau.