The tornado frequency increases in the spring as the warm and cold seasons battle it out in the U.S.
Warm, humid air surges into the South during the spring months, while colder air remains in place across the northern tier of the country. The clash of warm, humid air and cooler, drier air to the north creates instability for thunderstorms to develop.
Another key ingredient for severe thunderstorm and tornado development is a powerful jet stream, or a corridor of fast winds around the altitude where planes fly. When there are powerful winds high in the atmosphere and weaker winds at the surface, a twisting motion in the atmosphere can help to produce rotating thunderstorms capable of spawning tornadoes.
During the spring months, the jet stream is often still potent across the U.S. before it shifts too far to the north during the summer to support violent storms with tornadoes touching down.
The sun's rays are also strengthening during the spring months, promoting increased daytime heating that further reduces the instability of the atmosphere.
In addition to enduring frigid air, Minneapolis will see nuisance snow return this weekend.
The worst of the ice headed to the eastern U.S. will focus on the I-81 corridor from Virginia to southern Pennsylvania.
While heavy snow and ice are not expected to fall over much of the Midwest Sunday into Monday, some slippery roads and travel disruptions are likely.
Fresh cold and the return of Santa Ana winds are in store for Southern California to start the new week.
A magnitude 4.5 earthquake shook the ground near Jones, Okla., Saturday afternoon.
More snow is on the way for Cleveland late this weekend.
Oswego, NY (1958)
Beginning of a famous snowburst. Snowstorm began on the 7th and ended on the 11th... However, the first 22 hours gave 33". Total snowfall measured 66.7" when it finally ended on the 11th. There was an 11" snowcover before it all began. Syracuse had only 6" in this period.
Louisville, KY (1885)
15.0" snow set 24 hour snowfall record and single storm total for city (7th-8th).
Connecticut River (1740)
Early snows and hard freeze followed by a thaw and heavy rains produced the greatest flood on Connecticut River in 50 years; on Merrimac in 70 years.