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RADAR—sends a beam of microwave energy

RADAR—sends a beam of microwave energy which bounces off objects of certain size (e.g., raindrops) and returns a signal. US RADAR stations. http://www.srh.noaa.gov/bna/. Doppler effect —movement towards the RADAR intensifies the return signal; movement away from RADAR

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RADAR—sends a beam of microwave energy

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  1. RADAR—sends a beam of microwave energy which bounces off objects of certain size (e.g., raindrops) and returns a signal

  2. US RADAR stations http://www.srh.noaa.gov/bna/

  3. Doppler effect—movement towards the RADAR intensifies the return signal; movement away from RADAR decreases return signal

  4. Doppler RADAR --detects rotation in a mesocyclone

  5. Radial velocity map—shows relative movement of rainfall, towards RADAR (negative) or away from RADAR (positive) Radar

  6. RADAR has shown that many tornadoes form at the southwest sides of mesocyclones in an area known as the ‘hook’ (RADAR images of the hook are said to show a ‘hook echo’)

  7. Doppler RADAR

  8. Portable Doppler RADAR

  9. At the center of some large mesocyclones there is an area of weak RADAR reflectivity. This area is known as the Bounded Weak Echo Region (BWER)

  10. BWER—area of low RADAR return signal; is likely due to very strong updrafts

  11. Since 1982, successful tornado forecasts have increased and false alarms have declined. This is due mainly to the advent of Doppler RADAR in 1982

  12. MYTH of TRUTH? • Areas near lakes, rivers, and mountains are safe • from tornadoes. MYTH. No place is safe from tornadoes. • Windows should be opened before a tornado approaches to • equalize the pressure. MYTH. Leave the windows alone, and go immediately to your safe room or basement. • If you are driving and a tornado is sighted, you should turn and drive • at right angles to the storm. MYTH. Find shelter in a sturdy building. Many people are killed in their cars.

  13. MYTH or TRUTH • Large cities are not at danger from tornadoes MYTH. Nashville was hit by a tornado in April 1998. Oklahoma City has been hit by ~100 tornadoes in the last 100 years.

  14. Reduction in the number of tornado deaths after 1950 is attributed to: 1) use of RADAR to detect storms and issue warnings; 2) stronger building design; and 3) public awareness/education

  15. If tornado warning is issued for your area: • Go to your pre-designated interior room, basement • Stay away from windows • Get out of cars • Leave mobile homes and go to nearest sturdy shelter • If caught outside in tornado, lay flat in a ditch or low spot (flying debris is the cause of most tornado deaths)

  16. Tornadoes preferentially kill: • The elderly • Mobile home residents • Occupants of exterior rooms with windows • Those unaware of broadcast tornado warnings

  17. WATCHES AND WARNINGS Tornado watch—issued when conditions are right for producing tornadoes; time to stay tuned for later forecasts Tornado warning—issued when a tornado has been spotted by eyewitness or by Doppler RADAR; time to seek safe shelter

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