National Weather Service United States Department of Commerce

Thunderstorm season is rapidly approaching; bringing the possibility of large hail, strong straight-line winds, and tornadoes. Other summer hazards include dangerous heat. People can protect themselves from these hazards with a few simple preparations.

Know the terms.  When a weather watch or warning is issued, do you know what it means and what you should do?  The National Weather Service (NWS) uses the following definitions for summer hazards:

     A Severe Thunderstorm has wind gusts of 58 mph or higher and/or hail at least 1 inch in diameter.  Lightning is NOT a criteria for a severe thunderstorm as ALL thunderstorms generate lightning and should be considered dangerous.

     A Tornado or Severe Thunderstorm Watch means tornadoes or severe thunderstorms are possible.  The storms have not yet developed or moved into the watch area, so they are issued for a large area and for several hours.  You should monitor weather forecasts, watch for storms approaching your location, and be prepared to take shelter if a warning is issued.

     A Tornado or Severe Thunderstorm Warning means a tornado or severe thunderstorm is occurring or about to occur.  You need to take shelter immediately!

     A Flash Flood Watch means flash flooding is possible.  Flooding is not yet occurring, so they are issued for a large area and for several hours.  You should monitor weather forecasts, watch for heavy rain or rising water, and be prepared to leave for higher ground if a warning is issued.

     A Flash Flood Warning means a flash flood is occurring or about to occur.  You need to get to higher ground immediately!

     A Heat Advisory means heat index values will reach 100 degrees or higher; or a maximum heat index between 95 and 100 degrees will occur for
at least four consecutive days.

     An Excessive Heat Warning means heat index values will reach 105 degrees or higher with a minimum heat index of 75 degrees for at least 48
hours; or maximum heat index of 100 degrees or higher for at least four consecutive days.

Get the warnings. Storms can develop quickly, so you need to be able to get warnings wherever you are and at any time of day. Warnings are available from many sources; know which sources work for you and how to get additional information about the hazard.

NOAA Weather Radio is a network of radio stations operated by the National Weather Service.  Special receivers are activated when warnings are issued, so it’s like having a personal siren in your home or office.  The receivers have battery backup, ensuring you will receive the warnings even if the power is out.  The warnings are repeated every one to two minutes and frequent bulletins updating the storm’s location and track are included in the broadcast.  NOAA Weather Radio stations serving South Dakota are listed at

National Weather Service web sites and provide maps of active alerts and warning details such as expected hazards, impacts, storm tracks, and locations affected.

Cell phones can receive official messages through Wireless Emergency Alerts.  This is a free service for which you do not have to sign up or download.  Alerts are broadcast from cell towers in the vicinity of an emergency, so you will receive them for your current location.  You can also download other notification apps.  Check whether they will provide alerts for the area you specify or your current location.

NWS Twitter feeds include warnings. You can follow the Rapid City NWS at

Local radio, television, and cable systems broadcast warnings through the Emergency Alert System.  Warnings are not available on satellite TV channels unless you are watching a local station or when streaming videos.

Warning sirens are used by many communities for life-threatening situations—not just tornadoes.  They are intended to notify people outdoors to get inside, so you may not be able to hear them in office buildings or stores. 

Build a Kit.  Even in the summer, storms can cause power outages that last a day or two, so you still need to have emergency supplies at home.  Essential items such as flashlights and batteries, a battery-powered radio, first aid kit, non-perishable food, and water for drinking and other uses should be ready when needed.  Have a corded telephone to make and receive phone calls if the power is out at your residence or nearby cell tower.

If you live in a flood prone area, you also need to assemble a kit in a plastic tote or rolling suitcase to take with you if you need to evacuate. This kit should include cash, important documents, clothing, prescription medication and medical supplies, baby items, and pet supplies.

A list with more items to include in your kit is available at

Find a shelter.
          At home:

          • Go to the basement or small interior room on the ground floor, such as a closet, bathroom, or hallway.

          • Get under the stairwell or a sturdy table and cover yourself with pillows or blankets.

          • Avoid the corners and exterior walls of the house.

          • Stay away from windows.  Do not open the windows; it does not reduce damage to the structure.

          • Mobile home residents should go to a shelter well before the storm reaches them.  If there isn’t time or a shelter available: lie flat in a ditch, ravine, or culvert away from the home and cover your head.

          In public facilities or large buildings:

          • Go to the designated shelter, usually a room on the lowest level.  Use the stairs, not the elevator.

          • Stay away from large windows and skylights.

          • Do not remain in large rooms with high, unsupported roofs, such as gymnasiums, halls, warehouses, or church sanctuaries.

          If caught outside:

          • Leave your vehicle.  Lie flat in a low area like a ditch or culvert and cover your head.  Choose a location clear of trees that may fall on you and watch for rising water from heavy rain.

          • Do not take shelter under a highway overpass.  You can be injured when strong winds and debris are channeled through the small opening under the bridge.

          • Do not try to drive away from a tornado in a city, heavy traffic, or mountainous areas.

Make a Communications Plan.  Your family members may not be together or at home during an emergency.  Making a communications plan will enable you to contact each other and may help you reunite sooner.  Basic steps in a plan include making sure everyone knows where to go, how to contact each other, and meeting places if you can’t get back home.  A guide for creating a plan is at


Have an Escape Route.  Isolated thunderstorms with intense heavy rain can lead to dangerous flash floods, especially in the Black Hills.  Larger storm systems can cause widespread flooding that swells streams and rivers, covering roads and highways. You need to be able to react quickly if your home is threatened by rising water.

  • Learn if your home or workplace is in or near a floodplain by using the FEMA Flood Map Service Center.
  • Know the streams you cross often so you know if you’re approaching a flooded area.  Find the best way to get to higher ground without having to cross a stream when evacuation orders are issued.
  • When camping, choose campsites away from streams.  Do not camp where your only exit crosses a stream.
  • Watch for signs of intense storms upstream of your location that can cause flash flooding downstream. If you see water starting to rise, leave immediately; don’t wait for a warning or evacuation notice.
  • If you do approach water over a road, turn around. Do not drive into the water; the road or bridge may be already washed out. Most vehicles can be swept away by only one to two feet of moving water.

For additional information, contact your county emergency management office or visit the National Weather Service web site, Department of Homeland Security or the American Red Cross