Comparison of the dynamics of a land vs. oceanic explosive cyclone.

Abstract

Two explosively developing cyclones are analyzed and compared using a similar diagnostic approach. A continental cyclone developed over the U.S. Midwest during 14-17 November 1988 and was analyzed using NMC Nested Grid model analysis fields and GOES IR imagery. A maritime cyclone rapidly developed over the western North Atlantic Ocean during 03-05 January 1989. The NMC Spectral Model and GOES im­agery are employed to describe the development of this storm. Upper-level vorticity, di­vergence and jet streak placement are examined along with low-level thermal advection, boundary layer heating and static stability for each storm. Results indicate that the land and ocean storms have similar magnitude upper-level divergence associated with 300 mb jet streaks, however, they evolve differently. At low­ levels, there are equal contributions from advection and surface heating during rapid development in the ocean case while advection was the primary contribution in the land case. The initial static stability was low for both cyclones, however, the ocean case maintained low static stability and this appears to be a major factor in determining the depth and speed of rapid cyclone development.