Tropical Cyclone 04B developed over the northern Bay of Bengal on Friday.  The circulation around an area of low pressure southeast of India strengthened on Friday and the Joint Typhoon Warning Center (JTWC) designated the system as Tropical Cyclone 04B.  Data from a scatterometer on a satellite indicated there were winds to 45 m.p.h. (75 km/h) in the western part of the circulation.  The Indian Meteorological Department was classifying the low pressure system as a depression and that was why it did not have a name.

At 4:00 p.m. EDT on Friday the center of Tropical Cyclone 04B was located at latitude 18.7°N and longitude 86.9°E which put it about 340 miles (550 km) southwest of Kolkata, India.  It was moving toward the north at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 994 mb.

Although there was a well defined low level center of circulation, the rest of the circulation of Tropical Cyclone 04B was not particularly well organized.  There were no strong thunderstorms near the center of circulation.  The stronger thunderstorms were occurring in a rainband 80 miles (130 km) northeast of the center of circulation.  Other bands revolving around the center consisted primarily of low clouds and showers.

Tropical Cyclone 04B is moving through an environment that is only marginally favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 28°C.  So, there is enough energy in the upper ocean to support intensification, but that is about the only factor favorable for intensification.  Tropical Cyclone 04B is moving underneath the western end of an upper level ridge.  The ridge is producing southeasterly winds which are blowing across the top of the circulation.  Those winds are also causing moderate vertical wind shear and the shear is probably the reason why the band of thunderstorms is displaced northeast of the center of circulation.  It also appears that the western side of the circulation of Tropical Cyclone 04B is also pulling some drier air from over India into the system.  Tropical Cyclone 04B is unlikely to intensify due to the effects of moderate wind shear and drier air.

The upper level ridge is steering Tropical Cyclone 04B toward the north.  On its anticipated track Tropical Cyclone 04B could make landfall near Kolkata in 24 to 30 hours.  The primary risk is locally heavy rain which could cause flooding.  The rain is likely to reach northeastern India a few hours before the center of circulation makes landfall.