Aspectos sinópticos y dinámicos del temporal del 29 de octubre al 3 de noviembre de 1985 sobre Costa Rica

Abstract

The synoptic situation from 29 October to 3 November 1995, which caused a temporal over Costa Rica, is analyzed. The free atmosphere maps show the persistence of a cyclonic vortex, during almost all the duration of the temporal, in the surroundings of the coasts of Gulf of Mexico. This vortex which was associated to Hurricane Juan extended to the upper troposphere in the firts days and had a surface central pressure of about 995 hPa. The hurricane produced a northward displacement of the intertropical Convergence Zone and originated an anticyclone in the Oriental Pacific around Costa Rica (which is not a climatic characteristic of the general circulation during these months as these latitudes). Consequence of this was the advection of equatorial air to the mountaun slopes on the Pacific side of Costa Rica and the establishment of a deep westerly flow, which extended to the middle troposphere. Over Costa Rica, it was observed a wind confluence line, which was associated to a convergence field and to a field of ascending vertical wind. The derived fields of horizontal divergence, relative vorticity, and vertical motion, not only show concordance between them, but also a marked coupling with the synoptic flow and the production of rains. These fields deviate, at least for an order of magnitude, from the average values expected for the region.