Atmospheric River Bringing Heavy Rain to Southern California and Heavy Snow to the Sierra Nevadas

A strong atmospheric river will continue heavy rain over southern California through Friday. The heaviest rainfall is ongoing today in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall has begun over the Sierra Nevada Mountains and will continue through Friday. Travel will become increasingly difficult over the passes due to snow and strong winds. Read More >

WEA, Smart Phone Apps, and Social Media

Just as the recent explosion in wireless technology and social media applications is changing the way we communicate, it is also changing the way that people are receiving warning information. While recent studies have shown that most citizens still receive weather warnings from traditional media such as television and radio, mobile phone applications and social media propagation of warning messages are becoming increasingly popular. This section highlights some of these new methods and highlights some of their strengths and weaknesses.

Wireless Emergency Alerts (WEA) are text messages of weather warnings and civil emergency messages sent as a text message to your mobile phone. Most major cell phone providers are now enabling propagation of these messages to their customers.

Strengths: (1) Immediate alert and receipt of warnings. (2) Service is free (text message charges do not apply). (3) Service is automatic. There is no need to sign up for the messages, although you can opt out by contacting your service provider. (4) The system allows you to receive warnings for your location anytime, anywhere.

Weaknesses: (1) Warning messages originate from cell towers that are located within a warning area. Any phone within range of a tower can be alerted, so some customers outside of a warning area may receive alerts. (2) Some older mobile phones may not be equipped to receive the messages. (3) These alerts are only being created for certain types of warnings.

Numerous Smart Phone Applications have been developed by private vendors to provide weather information. Some of the most sophisticated applications make use of National Weather Service “warning polygons” and the global positioning system (GPS) functionality of smart phones such that phones will alert only when located within the boundaries of a “warning polygon.”

Figure 25. Example of a warning alert from a smart phone application utilizing National Weather Service “warning polygons” along with the smart phone’s GPS functionality. This particular application alerts only if the phone is located within the “warning polygon,” illustrated by the black box on the display screen at the lower right.

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