Tornado Season

Emergency Management and Response Information Sharing and Analysis Center (EMR-ISAC) INFOGRAM 10-10  March 11, 2010

Tornado Season

Weather forecasters at the Storm Prediction Center (SPC) of the National Weather Service (NWS) predicted that the United States will experience an active tornado season this year. SPC meteorologists believe: “More tornadoes and other damaging storms may strike the Midwest this spring because cooler temperatures are on course to clash with warmer air pushed into the central U.S. by El Nino.”

“Tornadoes are nature’s most violent storms,” according to the Federal Emergency Management Agency’s (FEMA) web site. “Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long.” Although more frequently occurring in “Tornado Alley” of the Midwest (i.e., CO, KS, NE, SD, OK, and TX), every state is at some risk from this hazard.

Recognizing that tornadoes are a threat to the critical infrastructures of Emergency Services Sector (ESS) departments and agencies, in addition to citizens and their property, the Emergency Management and Response—Information Sharing and Analysis Center (EMR-ISAC) ascertained from the NWS that 800 tornadoes are reported nationwide each year. These weather events usually result in approximately 80 deaths and over 1,500 injuries annually. “Last year, 1,156 tornadoes occurred throughout the country and 21 people were killed.”

To assist ESS organizations with the consideration of protective and resilience measures for tornado incidents, the EMR-ISAC excerpted the following FEMA facts about this weather phenomenon:

· May strike quickly with little or no warning.

· Can appear nearly transparent until a funnel-shaped cloud forms.

· Generally move Southwest to Northeast, but can travel in any direction.

· Average forward speed is 30 MPH, but can reach up to 70 MPH.

· Could accompany tropical storms and hurricanes as they move onto land.

· More frequently happen east of the Rocky Mountains during spring and summer months.

· March through May is peak season in southern states; May through July in the northern states.

· Most likely occur between 3 p.m. and 9 p.m., but can happen at any time.

More information about tornadoes can be found at “The Online Tornado FAQ,” which is a web site of the National Oceanic and Atmospheric Administration (NOAA).