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.
A ferry has sunk off the coast of South Korea, leaving at least four dead and over 250 passengers missing.
Following some rain showers this Saturday, drier weather is in store for Boston by Monday to kick off the 118th annual Boston Marathon.
A mid-April snowstorm will focus on the northern Plains and Upper Midwest through Thursday, spreading snow from the Dakotas to Ontario.
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A harsh blast of cold air that moved over the Northeast on Tuesday night will be quick to leave.
Experts across the nation are searching for plausible solutions to the defects of the nation's over-stressed and antiquated power system before severe weather season takes full rein.
St. Paul, MN (1965)
Flood crest exceeded previous record high by 4 feet. Former marks generally surpassed down to Hannibal, MO, by May 1st; only 12 lives lost due to timely warnings. Damage exceeded $100 million.
Oklahoma City, OH (1990)
93 mph wind gust - one of the strongest gust at Will Rogers Airport in the last 40 years.
Charleston, SC, reaches 32 degrees -- latest ever there. At Wilmington, NC, snow accumulated up to 6" on boards. Fayetteville, NC, had 4" on the 15th -- one of the latest snowstorms ever. Snow flurries as far south as Milledgeville, GA. Severe freeze from Georgia to Texas killed cotton.