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.
Dry conditions and above-normal temperatures are expected for Super Bowl Sunday in Santa Clara, California.
Warmer air will build from California to Washington on Monday and Tuesday raising temperatures to near-record levels.
The new week will bring more opportunities for snow to create slick travel in the northeastern United States, starting with a winter storm set to sideswipe New England on Monday.
Cold and snow showers are in store for the New Hampshire primary on Tuesday but should not significantly impact voter turnout.
As the Denver Broncos and Carolina Panthers clash for the Super Bowl 50 title in Santa Clara, California, on Sunday, they will do so in one of the most energy-efficient stadiums in the world.
A magnitude-6.4 earthquake shook southern Taiwan shortly before 4 a.m. local time on Saturday, according to the U.S. Geological Survey.
Door County, WI (1985)
Up to 30 in. of snow over the past 2 days in parts of Door County, WI (NW of Green Bay). Lake squalls.
Johnstown, PA (1986)
Lightning during a snowstorm set fire to a church and caused damage.
Boston, MA (1861)
46 degrees on this date, -14 degrees on the 8th, and 60 degrees on the 11th.