The Enhanced Fujita Scale is used to assign tornadoes a rating based on estimated wind speeds and damage.
The EF Scale became operational on Feb. 1, 2007. It was revised from the original Fujita Scale, developed in 1971 by Tetsuya Fujita, to better reflect wind speed with damage observed in tornado surveys.
Deadly Severe Weather Facts & Safety Tips:
Severe thunderstorms will threaten holiday festivities across parts of the Midwest to close out the extended Labor Day weekend.
Severe threats include damaging winds, flooding downpours, large hail and some tornadoes.
The next Atlantic tropical depression or storm may take shape in the southwestern Gulf of Mexico's Bay of Campeche by midweek.
A second volcanic eruption occurred on Sunday morning in Iceland in the same area that had one on Friday.
Labor Day weekend traditionally marks the unofficial end to summer, but the weather has another idea in mind around Washington, D.C., with a prolonged stretch of summer heat underway.
Labor Day weekend traditionally marks the unofficial end to summer, but the weather has another idea in mind with summer warmth surging in around Boston.
Los Angeles, CA (1955)
110 degrees, hottest day ever in September. This mark was tied September 4, 1988.
Milwaukee, WI (1988)
Hottest summer on record. Six days of 100 degrees or greater and 36 days of 90 or above. Average temperature of 73.8 beat the old record of 72.8 set in 1921 and 1955. The normal average tempera- ture for a summer in Milwaukee is 68.3 degrees.
Washington Co., IA (1897)
Hail fell and drifted in piles 6 feet deep in Washington County.