Climate Assessment for 1996

The climate of 1996 can be characterized by several phenomena that reflect substantial deviations from the mean state of the atmosphere persisting from months to seasons. First, mature cold-episode conditions persisted across the tropical Pacific from November 1995 through May 1996 and contributed to large-scale anomalies of atmospheric circulation, temperature, and precipitation across the Tropics, the North Pacific and North America. These anomalies were in many respects opposite to those that had prevailed during the past several years in association with a prolonged period of tropical Pacific warm­episode conditions (ENSO). Second, strong tropical intraseasonal (MaddenñJulian oscillations) activity was observed during most of the year. The impact of these oscillations on extratropical circulation variability was most evident late in the year in association with strong variations in the eastward extent of the East Asian jet and in the attendant downstream circulation, temperature, and precipitation patterns over the eastern North Pacific and central North America. Third, a return to the strong negative phase of the atmospheric North Atlantic oscillation (NAO) during November 1995ñFebruary 1996, following a nearly continuous 15­yr period of positive-phase NAO conditions, played a critical role in affecting temperature and precipitation patterns across the North Atlantic, Eurasia, and northern Africa. The NAO also contributed to a significant decrease in wintertime temperatures across large portions of Siberia and northern Russia from those that had prevailed during much of the 1980s and early 1990s.

https://doi.org/10.1175/1520-0477-78.5s.S1

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