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U N D E R C O N S T R U C T I O N
Upper Level Cyclonic Systems
Trans-ridge Weaknesses
In some cases during the warmer months, the gap or cleavage between two existing subtropical highs can form an alley of cyclonic shear or even circulation. Termed a weakness, this corridor can serve to steer smaller features, such as an MCC or a tropical cyclone. Often in summer, the weakness will be home to pockets of cold air that increase the potential for diurnal and/or seabreeze convection. Continental thunderstorm groupings may drop into discontinuity (a phenomenon seen many times in late spring and summer over the lower Great Plains in 2007). The best way to view a weakness is by examining water vapor imagery. There are cases of breaching, however, where a weakening anticyclone is broken apart by upstream or lower latitude cyclonic systems, thus opening up a new pathway for disturbances to gravitate to higher latitudes.
"A Guide to Baroclinic Disturbances" is © 2007 by Larry Cosgrove.
All rights reserved.
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