Tuesday, June 7, 2011

Flash Flooding Safety Tips

Flooding and flash flooding occur every year in the Mid-South.  River flooding occurs seasonally when winter and spring rains combine with melting snow upstream to cause rivers and their tributaries to overflow their banks.  River flooding (such as we experienced in spring 2011) can occur over a period of weeks to months.  Flash floods on the other hand can occur suddenly and are typically attributed to excessive localized rainfall. The flooding occurs within a few hours of the heavy rain.

A Flash Flood Watch means that heavy rains could cause flooding in the specified area. Stay alert to the weather and have a plan in place should water begin to rise or a warning gets issued, particularly if you are in an area that has flooded before.

A Flash Flood Warning means that flash flooding is occurring or expected imminently.  If a warning is issued or water begins rising in your area, act quickly to exercise your plan and get to higher ground.
 
Here are some flash flood safety rules:
  • Leave areas subject to flooding, including low spots, valleys, stream banks, and flood plains.
  • Avoid areas that are flooded or have quickly-moving water. Do not attempt to cross a flowing stream where water is above ankle-deep.
  • When driving, know the depth of water in a low spot before crossing. The road bed may not be intact under the water. Remember, "Turn Around, Don't Drown!"  One foot of moving water is enough to lift and carry a car downstream.
  • If your vehicle stalls, abandon it immediately and seek higher ground. Water may rise rapidly and engulf your vehicle and it's occupants.
  • Be especially cautious at night when it is harder to recognize flood dangers.
  • Do not camp or park your vehicle along streams or drainage areas, especially when thunderstorms are possible.
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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Sunday, June 5, 2011

Tornado Safety

Tornadoes are violent columns of rotating air that are produced by severe thunderstorms.  Weak tornadoes produce wind of  65-85 mph, while the strongest (such as the Joplin, MO tornado of May 2011), produce wind of over 200 mph and can be 1/2 to 1 mile wide or greater. Not all severe thunderstorms produce tornadoes, only a small fraction do, but people should be alert for the possibility if and when a Severe Thunderstorm Warning is issued.

Tornado safety rules include:
  • At home or in small buildings, go to the basement or storm shelter, or to a windowless interior room such as a closet or bathroom on the lowest level.  Get under something sturdy such as a table or heavy bed.
  • Abandon mobile homes and vehicles for a sturdy structure.
  • In large buildings such as at school, shopping centers, hospitals, or factories/warehouses, go to the predesignated shelter area. Interior hallways on the lowest floor are best. Stay out of areas with high roofs or large roof spans, as they typically offer little to no protection from tornadic wind.
  • At all times, avoid windows or large panes of glass.
  • If outside and sturdy structures are not available, try to drive to the nearest sturdy structure for shelter.  If one is not available, lie down in an area that is lower than surrounding areas (ditch or ravine if possible) with arms/hands shielding your head.
  • When taking cover, have shoes on, photo ID on your person, cell phone (preferably charged in advance) with you, and crouch down and protect the back of your neck with your arms and hands.
A Tornado Watch, typically issued for a large area such as many counties, means that conditions are favorable for the development of severe thunderstorms that can produce tornadoes. Stay tuned to NOAA Weather Radio or other commercial outlets for possible warnings and watch the sky for the possibility of developing severe weather.  Have your plan ready should a warning be issued and be ready to exercise it.

A Tornado Warning, typically issued for a small area in the path of a storm, means that Doppler Radar has indicated the likelihood of a tornado or a tornado has been sighted by trained spotters or law enforcement.  If you are in the path of the storm, immediately find shelter using the rules above.

A Tornado Emergency is not a warning type, but is issued (usually following the original Tornado Warning) when a large and destructive tornado has been confirmed and is moving into a populated area.  The risk of destruction and fatalities is high and an elevated call-to-action is required.  Everyone in the storm's path should immediately take action.

For more information on the activation of outdoor warning sirens within the Memphis metropolitan area, please see this page if viewing on your PC or this page if viewing from a mobile device.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.