Tuesday…Warning Reception

The Iowa Homeland Security and Emergency Management Division and the National Weather Service have declared the week of March 23 through March 27, 2015 Severe Weather Awareness Week. Severe Weather Awareness Week is an annual event to remind Iowans that severe weather is part of living in our state and that understanding the risks and how to respond to them can save lives. Each morning during severe weather awareness week, we’ll be focusing on a different severe weather topic. The topics this year include:

  • Monday – Flash Flooding
  • Tuesday – Warning Reception
  • Wednesday – Tornadoes
  • Thursday – Severe Thunderstorms
  • Friday – Family Preparedness

There are so many different ways to find weather information these days and you just have to determine your preferred method. This is especially true during severe weather season as one of the most important precautions you can take in order to protect you and your family from severe weather is to be weather aware. Being weather aware means you are informed of the updated weather forecasts and potential weather hazards. It doesn’t stop at gathering weather information, what to do and where to go in a severe weather situation can save you and your family’s life. We highly recommend that you have multiple methods to receive National Weather Service Watch and Warning information. Ask yourself; “What is my primary source for receiving Watches and Warnings?” Your answer could vary from the internet or mobile device, commercial TV or radio, and NOAA Weather Radio.  It is up to you though to remain weather aware and take action as needed during severe weather.

One of the first items that you need to know is what is the difference between a watch and a warning, and then what you should do if the NWS issues one of these. A watch (whether Severe or Tornado) is issued to provide advance notice when atmospheric conditions are favorable for thunderstorm development capable of producing severe weather (large hail and damaging winds), tornadoes, or flash flooding.


Broadcast Commercial Media

The National Weather Service has a strong relationship with the broadcast media. The NWS relies on the broadcast media to help broadcast NWS warnings to the public. This is a very important relationship since most Iowans get severe weather warnings from commercial media.

Television Media

Television meteorologists and broadcasters transmit NWS warnings and watches to the public. In addition, they usually add value to the warnings with radar displays and visually explain where the threat is located. Studies have discovered that local commercial TV is the primary source of warning information (Wolf, 2009) reaching the majority of people. Warning information is supplied through reading NWS warnings on the air, or by scrolls providing the information. During high-end events, television stations will often go wall-to-wall with weather coverage, interrupting normal broadcasts. Warning reception from television stations is maximized during significant events in metro areas during daytime or evening hours and it is minimized during marginal severe events in rural areas at night.

Radio Media

Radio media is another important way Iowans get severe weather watches and warnings. The radio media varies from large AM stations with very extensive coverage areas to smaller stations scattered across Iowa. Several stations provide wall-to-wall severe weather coverage during high end events with a focus on their local area.

The Emergency Alert System (EAS) is used to broadcast severe weather warnings. When stations are closed, they use the EAS to transmit severe weather warnings directly from the NWS to the public.

NOAA Weather Radio

Known as the “Voice of the National Weather Service,” NOAA All Hazards Weather Radio (NWR) is provided as a public service by the National Oceanic & Atmospheric Administration (NOAA), part of the Department of Commerce. NWR includes more than 900 transmitters, covering all 50 states, adjacent coastal waters, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific Territories. NWR requires a special radio receiver or scanner capable of picking up the signal. Broadcasts are found in the public service band at these seven frequencies (MHz): NWRFrequencies

Modern NWR Receivers are often SAME (Specific Area Message Encoding) capable, meaning they can be setup to only alert or turn on for specific areas (usually counties in the Midwest) by programming them via a small keypad on the receiver. In this manner, you won’t be awakened at 3 a.m. for a warning which is not of interest to you.

All Iowans should benefit from NWR since a NWR transmitter is likely within range. It is a great way to get a warning in the middle of the night when you may be asleep, or in remote locations.

NOAA Weather Radio is one of the best indoor warning systems available. Unfortunately, studies have shown that only 5-10 percent of the population owns a weather radio (Wolf, 2009).


NWS forecast offices have pre-arranged agreements with emergency managers to facilitate the receipt and transmission of emergency non-weather related messages. These messages can be broadcast over the NOAA Weather Radio and may interrupt the regular broadcast using special alert tones and SAME codes. Examples of these non-weather events include:

  • Toxic chemical incidents
  • Nuclear power plant accidents
  • AMBER Alerts

Outdoor Warning System

When it comes to severe weather, outdoor warning systems (sometimes known as sirens) have one purpose and one purpose only – to alert people who are outdoors that something dangerous is happening and they should go inside. Depending on local policy, sirens may be sounded for a variety of life-threatening hazards, but always with the intent that people outdoors should seek shelter.

Across Iowa, local siren activation policies vary widely. The city or county government is usually in charge of siren activation policy. The National Weather Service does not have the authority to activate siren systems, but the NWS works closely with communities with severe weather warning systems, including storm sirens.

For severe weather, most communities sound sirens anytime a tornado warning is in effect for their area. Other communities have stricter policies and only activate the outdoor warning system for actual tornado sightings, while a few activate sirens for both severe thunderstorm and tornado warnings. The NWS encourages communities to activate outdoor warning sirens for high-end severe thunderstorms (wind speeds above 75 mph and/or hail of two inches or greater). To find out your community’s siren policy, check with the local emergency management agency.

Mobile Devices, Social Media, and the Internet

Select high impact NWS warnings are sent to cell phones as a Wireless Emergency Alert (WEA). Additional alerts from other government agencies, such as FEMA, may also be sent to your phone. Here is how it works: If you are at home, or traveling in an area where a warning has been issued, your phone will receive alerts broadcast by nearby cell towers. If your phone is enabled to receive alerts, your phone will receive an alert the resembles a text message, the message will be no longer than 90 characters. The alert will have a special tone and vibration, repeated twice, so that you will be able to tell it apart from a regular message. If you receive an alert, you should follow any action advised by the emergency message and seek additional details. The service is free of charge and messages will not count towards texting limits on your wireless plan. It comes enabled on newer cell phones depending on the carrier.

In recent years, many more people receive severe weather warnings over the internet. Most people still use desktop or laptop PC’s to gain access to the internet. Internet access is expanding rapidly and now many people have internet access on their cellular phones or tablets.

People use various websites which have access to NWS warnings. The direct way to access NWS warnings is over its website at: weather.gov. For central Iowa, add “Des Moines” to the end of the URL or: weather.gov/desmoines. The NWS website is also available on mobile devices at mobile.weather.gov. Now available is an experimental “NWS Widget” that adapts to your PC or mobile device using any internet browser. See the image below for some quick instructions. The NWS Widget sort of works as an app on your smart phone or tablet. There are many other third-party apps available that display NWS watches and warnings,

Another major advantage about the internet is viewing warnings graphically. Since NWS warnings are issued based on the storm and not the county, modern severe weather warnings are best viewed graphically to see exactly where the warning is in effect.

Social media is a tremendous tool in receiving and sending weather information. However, Social Media is not an official WARNING Dissemination Method, so you may not always receive the information you’re looking for or need to stay safe. Also, be mindful on what you share and re-tweet, there are a lot of fake images that surface during major severe weather event. Make sure you trust the source of the image! Follow and interact with us on Facebook and Twitter!