A case
study of the unseasonable 21 December 1980 cold surge over South America is
presented below. The data used to make
the plots are the ECMWF 2.5° ERA-40 grids.
• 925-mb Temperature, 925–500-mb Lapse Rate,
and 850–500-mb Shear
• Sea Level Pressure, 1000–500-mb Thickness, and 300-mb Wind
• 500-mb Geopotential Height, 500-mb Absolute Vorticity, 500-mb Wind, and
850-mb Relative Vorticity