According to AccuWeather Long Range Weather Expert Paul Pastelok, "We expect a southward dip in steering-level winds to occur much of the time over a large part of the Midwest to the Eastern states during March and the first part of April." This dip of strong winds high in the atmosphere, known as a jet stream trough, will generally keep warm, moist air at bay from near the Mississippi River to the Atlantic coast. Thunderstorms are fueled by rising warm, moist air. As a general rule, the lower the temperature near the ground, the lower the risk for tornadoes and violent thunderstorms."This year, the ground is colder, the Great Lakes have an extensive amount of ice and the Gulf of Mexico waters are starting off colder than average," Pastelok said. "All of these can have a negative impact on temperatures in the lower atmosphere."
Over much of the Southeast, Midwest and Northeast, the tornado risk will be lower than average early on due to the colder-than-average environment expected.
http://www.accuweather.com/en/weather-news/spring-severe-weather-forecast-2014/24012981
