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Severe Weather: Receiving the Warning

Before it Strikes . . .  
Planning Ahead
Understanding the Forecast
Receiving the Warning

Staying Safe . . .  
Hail and Straight Line Winds


One of the most important precautions you can take to protect yourself and your family from severe weather is to remain weather aware. Being weather aware means you are informed of the weather forecast and alert to the potential hazards. Knowing what to do and where to go when watches and warnings are issued is key to your safety, but a watch or warning is only helpful if you are aware of it.

How do you receive information about watches and warnings? With today's technology there are many different ways to receive this information including: commercial TV and radio, NOAA Weather Radio, outdoor warning systems, cell phone applications and text messaging services, and the internet. However, all of these technologies have one thing in common: It is up to you to remain weather aware and actively listen for watches and warnings!

What to Listen For and Actions to Take:

Watch Issued to give advanced notice when conditions are favorable for the development of severe weather, whether it is severe thunderstorms, tornadoes, or flash flooding.
When a watch is issued for your area, pay attention to the weather and be prepared to take action should a warning be issued.
Warning Issued when severe weather is occurring or imminent.
When a warning is issued for your area, you should take action immediately to protect your life and your property.

Commercial Broadcast Media

The National Weather Service (NWS) has a strong relationship with the broadcast media. The NWS relies on the broadcast media to help relay 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 to the public. In addition, they usually add value to the warnings with radar displays and a visual explanation of where the threat is. Studies have discovered that local commercial TV is the primary source of warning information (Wolf, 2009) reaching the majority of the people. Warning information is supplied through reading NWS warnings on the air, or by occasional scrolls providing the information. During high-end events, television stations will often go wall-to-wall with weather coverage, interrupting normal broadcasts. Warning coverage from television stations is maximized during significant events in metro areas during daytime or evening hours and is minimized during marginal severe events in rural areas at night.

Radio Media

Radio is another important way Iowans get severe weather warnings. Radio media vary from large AM stations with wide coverage areas to smaller FM stations scattered across the state. Several stations will 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 and Atmospheric Administration (NOAA). Nationwide, NWR includes more than 1,000 transmitters in 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:

162.400 MHz (Ch. 1) 162.425 MHz (Ch. 2) 162.450 MHz (Ch. 3)
162.475 MHz (Ch. 4) 162.500 MHz (Ch. 5) 162.525 MHz (Ch. 6)
162.550 MHz (Ch. 7)    

Modern NWR receivers are often SAME (Specific Area Message Encoding) capable, meaning they can be configured to only alert for specific areas (usually counties in the Midwest) and specific threats 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 an NWR transmitter is likely within range. It is a great way to get a warning in remote locations or the middle of the night when you may be asleep.

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

What is "All Hazards" Messaging?

NWS forecast offices have pre-arranged agreements with emergency managers to facilitate the receipt and transmission of non-weather related emergency 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

Additional Information on NOAA Weather Radio:

NOAA Weather Radio
SAME Codes for Iowa Counties
Coverage Map for Iowa

Outdoor Warning System

When it comes to severe weather, outdoor waning 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. Outdoor sirens have never been, nor ever will be, designed to be heard indoors. Thus, it is crucial that you do not rely on sirens as your primary means of receiving severe weather warnings.

Across Iowa, local siren activation policies vary widely with city or county governments usually in charge of sounding the sirens. The National Weather Service does not have the authority or ability 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 any time 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 communities 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 75mph and/or hail with a diameter of two inches or greater). To find out your community's siren policy, check with the local emergency management agency.

Cellular Phone and Mobile Devices

People can receive cell phone notifications for NWS warnings via either text messaging services or smartphone applications (apps). Services vary depending on the carrier and phone models. Providers typically charge a small fee to send emergency alert notifications, including severe weather warnings, via text message. Smartphone warning apps are either free or cost a few dollars, and can be configured to only alert for certain locations. Since most people carry a cell phone or other mobile device, receiving severe weather warnings via this method is an excellent way to keep informed. However, remember that it may take a few minutes to receive the warning depending on network coverage and which app is used.

A new service called Wireless Emergency Alerts (WEA) allows the National Weather Service and other government agencies to send alerts of current life-threatening situations to cell phones in an affected region. A WEA will appear like a text message on your phone and only convey the most basic information, such as: the threat, how long the threat should last, and who issued the alert. WEAs are meant to alert you that there is a threat in your area and you should take shelter and seek more information. The only NWS warnings that will be sent via WEA are: tornado, flash flood, extreme wind, dust storm, hurricane, ice storm, and blizzard warnings. Other messages such as amber alerts and presidential alerts are also sent out as a WEA. All smartphones manufactured after June of 2012 will be able to receive WEAs, and many older smartphones will be updated to receive these messages. Many new non-smartphone cell phones are also capable of receiving WEAs. Please check with your cellular provider to see if your phone is compatible. Details about this new service can be found here.

The Internet

Des Moines NWS Main Page

The internet is a popular way for many more people to receive serve weather warnings. While many 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 and tablets.

People use various websites which have access to NWS warnings. The direct way to access NWS warnings is through its website, For central Iowa, add "Des Moines" to the end of the URL or:

One major advantage in using 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 websites are gaining in popularity. In the future, warnings may be received on these sites as well. The number of people receiving warnings over the internet will likely continue to increase.

Friends and Family

Relying on friends and family should not be your primary means of receiving a warning. However, time after time, post-storm surveys conducted by the National Weather Service and social scientists have found that one of the biggest reasons people sought shelter from a storm is because a friend or family member called to warn them of the storm. This has been proven to save lives. If you are in the path of a storm and have moved to safety, reach out to family and friends who are also affected and encourage them to do the same.

If you are not affected by a storm, but are aware of a warning covering a friend or loved one nearby, or even across the country, reach out to them and make them aware of the dangerous situation. They may not have heard the warning! Hearing from a loved one helps to personalize the threat of severe weather and encourages people to take actions to protect themselves.

Additional Links and Info:

Receiving Warnings (pdf) is the U.S. government's official web portal to all federal, state and local government web resources and services.