On the morning of July 25 a surface circulation had formed and the cyclone became a tropical depression.

In the past, oceanographers were forced to ignore surface circulation because it was too complex to be measured, he said.

On September 5, satellite imagery suggested a surface circulation had developed, possibly due to interaction with a cold low.

The system continued to organize early on July 28, and that afternoon it developed a surface circulation.

By October 19, the system became stationary and developed a surface circulation.

The following day, a larger surface circulation developed as the low moved towards the northwest.

On December 20, the surface circulation began to emerge south of its central convection.

Upon entering the gulf, a surface circulation developed; however, convection associated with the system was not concentrated around the center.

The system developed a weak surface circulation which progressed across the central Philippines.

On September 7 the system formed a surface circulation, and tropical depression advisories began that day.