Wireless Emergency Alerts

From our friends at Clark Regional Emergency Services Agency 
The Skinny on Wireless Emergency Alerts

Emergency officials now have a new way to send warnings directly to cell phones in affected areas - Wireless Emergency Alerts (WEA's). Here is the Skinny on these new alerts. These short messages that may look like a text message, can be sent to all phones within range of designated cell towers through the Commercial Mobile Alert System (CMAS). The alerts will tell you the type of warning, the affected area, and the duration. You'll need to turn to other sources, such as television or your NOAA All-Hazard radio, to get more detailed information about what is happening and what actions you should take.

 ** Please Note - Currently CMAS alerts are set up to alert an entire county if there is an emergency within that area. At this time, there is no way to just select the area that may be affected. The Three Types of Wireless Emergency Alerts: The Commercial Mobile Alert System (CMAS) can be used to broadcast three types of emergency alerts:
PRESIDENTIAL ALERTS - Issued by the U.S. President in the event of a nationwide emergency. IMMINENT THREAT ALERTS - Typically issued by the National Weather Service; in the Portland/Vancouver Metro area, these would include tornado, flooding, volcano, ice storm and blizzard warnings.
 AMBER ALERTS - Issued by law enforcement to share information about child abduction. Is Your Phone

Ready for WEA? If you have an older model phone, you may not receive the Wireless Emergency Alerts. Most newer model phones of the iPhone and Android models are currently coming with this added feature. Check with your service provider to find out if your phone is WEA-capable. AT&T, Cricket, Sprint, T-Mobile, and Verizon all have information about the new alert system on their websites.

Key Things to Know: WEA messages may look like a text, or appear over your home screen. The alert message will include a unique ringtone and vibration. You will never be charged for WEA messages. Emergency alerts will not interrupt any calls or downloads in progress. If you’re on the phone when the alert goes out, you’ll get the message when you end your call. You need not have GPS or any other special features turned on to receive the alerts. The system does not identify your location or phone number — it simply sends the message to all devices in a given area. If you’re on the road and enter an area with an active warning, you’ll receive a WEA message as soon as you come within range of one of the affected cell towers.
Cell Tower Geography May Lead to Over-Warning:
Because cell towers broadcast in a radius or circle, their coverage areas don't line up neatly with county boundaries. This means you may receive warnings for an adjacent county if you are within a few miles of the border. The alerts are delivered directly from cell tower to cell phone through a one-way broadcast. The Commercial Mobile Alert System does not track or locate individual cell phones or phone numbers - it simply broadcasts to all phones within range. 

Unfortunately in some cases, this may result in over-warning. For example, if a weather warning is issued for a particular county, it will go to all towers that serve that county. Towers in urban areas generally serve a radius of two to five miles, and in rural areas up to 10 miles, so the warning message may reach a little beyond the warning boundaries. We have seen issues with this locally with snow alerts this season. Because of the reporting and issuing area covered, areas that really are not affected received snow alerts because they were within areas cell towers that broadcast also to areas that would be affected. Eventually these alerts will get to where we can pin point much more just the affected areas instead of the entire county. Until then this is a small hiccup we will have to deal with