Re-examination of the split cold front in the British Isles cyclone of 17 July 1980



An analysis of an MM5 model simulation of a cyclone that passed over the British Isles on 17 July 1980 indicates that the cyclone had some characteristics of both the split-cold-front model of Browning and Monk (1982) and of a schematic by Browning and Roberts (1996). Most importantly, the cyclone had the characteristic upper-level baroclinic zone and its associated vertical velocity in advance of the surface front. This is an integral part of both the split-cold-front model of Browning and Monk and Browning and Roberts's schematic, and confirms the analysis of Browning and Monk. Simultaneously at different locations, the cyclone also had the characteristics of a warm occlusion in the lower levels with the portion of the cold front that was above the warm front tipped forward with height. The lower and upper portions of the cold front were not only fronts in equivalent potential temperature, as proposed by Browning and Monk, but true baroclinic zones with significant associated vertical velocity.

The complex structure of this cyclone in the British Isles was similar to that of some storms in the Pacific Northwest of the United States (Locatelli et al. 2005). Copyright © 2005 Royal Meteorological Society.