Planetary-scale forcing of the january 1977 weather.

The type of weather anomalies that occurred in the United States during January 1977 are typical of a planetary-scale wave phenomenon called stratospheric sudden warming (SSW). Specific changes in weather parameters nearly always accompany SSW. Blocking ridges (intensified high-pressure cells) develop over the oceans, the North Pole warms, mid-latitudes cool, and continental temperatures plunge. These characteristics usually persist for at least a month. When the SSW is strong, as in January 1958, 1963, and 1977, the accompanying weather anomalies can be unusually severe.