Puerto Vallarta is under a hurricane watch

Roslyn looks better organized on satellite imagery this evening and Puerto Vallarta has been placed under a hurricane watch.

A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.

The cyclone will move over warm sea surface temperatures within a weak deep-layer shear environment during the next couple of days or so. This is expected to support strengthening, and Roslyn is forecast to become a hurricane . . .