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.
The coldest air of the season so far and some snow will pour into the northwestern United States by early next week.
Arctic air settling over Germany may prompt children to leave their shoes for St. Nicholas indoors instead of outside before going to bed on Monday night.
A deadly wildfire exploded in Tennessee this week, charring a popular resort town and causing devastating damage.
On the heels of Cyclone Nada, a new and more significant tropical cyclone threatens to take aim at India next week.
Dashing hopes for Christmas Day snowmen and white rolling hills, forecasters predict Britain's weather pattern will leave more to be desired on Dec. 25.
Rounds of heavy rain will heighten the risk for flash flooding across portions of the southern United States through the weekend.
As colder air sweeps into the northeastern United States, temperatures will settle to seasonable levels, and lake-effect snow will erupt into Saturday night.
Thousands of firefighters from across the country answered the call to help save the South, not just on the front lines but also back in camps supporting those out among the flames.
A tranquil beginning to December will be replaced by unsettled weather ahead of the holidays.