ULL and LLC

[txwatcher91]

ULL's have worked their way down to the surface before, over a period of many days, and have become TD's or TS's. Now the question is, if Hanna moved right under the ULL would the ULL "link" with the LLC or what would happen?

[meteorologist]

If an upper air low pressure trough interacted by passing directly over a hurricane or tropical storm it would probably deform the circulation to such a degree that the storm would cease to have tropical characteristics. More likely, the approach of the upper air system would steer the surface storm away from the upper air trough.

[theavocado]

Two things would prevent a linking up of a ULL and a LLC (of tropical nature).

The first is that a LLC has upward vertical motion and an ULL has downward vertical motion. Over a strong TC you'll actually develop a small upper level anticyclone as the mass evacuates out of the TC at the upper levels.

The second thing that would be an obstacle is a ULL tends to be a cold-core system, and the tropical LLC would be a warm core system.