Increasingly, the weather world's attention has been focused on the tropical Pacific where the El Nino and La Nina phenomena occur. These warm and cold water events have been shown to relate to certain jet stream configurations and anomalies of temperature and precipitation across many parts of the earth. In an El Nino year, the temperatures of the Pacific Ocean waters are warmer than usual causing flooding along the West Coast of the United States and relatively mild and stormy winters here in New England. The Subtropical Jet Stream becomes very strong during the winter months, keeping the very cold Polar air locked up north in Canada. The continental U.S. is invaded by moist, milder, Pacific Air.
Snowstorms can occur in New England, but the frequency is much lower than normal.
La Nina years in New England shows a pattern, of mild, snowless winters. Cold air tends to be pushed into the Rocky Mountain states and warmer air flows north out of the Gulf Coast states into the Northeast. This pattern usually lasts for about 9 - 18 months. It happened to coincide with the last two winters. This La Nada pattern promotes great temperature swings throughout North America during the winter months.