•The
convergence/divergence produced by the curvature and jetstreak effects cancels
each other to the south of the jetstream axis but enhances each
other to the north of the jetsream.
•The strongest
divergence aloft occurs on the northeast side of the trough, where a surface
low pressure tens to develop.
•The strongest convergence aloft occurs on the northwest
side of the trough, where a surface high pressure tends to develop. However, other processes
are more important that this upper-level convergence in affecting the development of high
pressure system.