Severe Weather Alerting: The Balance Between Speed and Accuracy
by JT Johnson, on Feb 15, 2017 3:09:42 PM
As we head into the more traditional severe weather season, we will see many references to severe weather preparedness in the coming weeks. Invariably, a severe weather safety awareness campaign will discuss the need to have multiple ways to get weather information for the severe weather situations. A NOAA Weather Radio, television, and AM/FM radio are the traditional means of hearing about severe weather alerts (watches/warnings). However, over the last several years, the number of mobile weather apps that have come on the market on IOS and Android devices is astounding. Thousands of apps claim to provide you with notification of severe weather warnings, but how good of a job are they doing?
It seems weather is a target space for many new app developers due to the relative ease in finding weather data from free sources. The simplicity of developing a new mobile app these days, with advanced software development tools, leads to the number of new weather apps continuing to grow. Many of the apps that show current conditions of temperature, sky conditions, humidity, wind speed and direction, etc. along with today’s and this week’s forecast do a fine job of conveying the observations from a nearby observing station and the forecast from the NOAA National Weather Service (NWS). Many of these apps are free or are at a very low price.
However, when it comes to severe weather alerts, you often get what you pay for. The notion of receiving a weather bulletin from the NWS and then decoding that information and sending it to an app’s users is a pretty simple concept until you dig into the details and worry about how many people need to receive the alert. More and more people depend on mobile app alerts as one of, if not the primary, way of receiving severe weather alerts.
WDT has had a form of weather alerting through text messaging (SMS) or email since 2002. In 2007, with the release of the first iPhone, we began working on the ability to issue alerts to mobile app users. We obtained four US patents related to the distribution of weather notifications to mobile devices through our Weather Mass Notification® system. Additionally, we have licensed 50+ patents related to the use of weather information on mobile devices. Today’s WDT’s alerting infrastructure services over 12 million end users through apps that we own and operate. So, we know a little about building alerting infrastructure to support a large user base and do so such that the end users can trust the app to provide them with information when they need it most.
WDT has struck a balance of speed and accuracy. In software, it is pretty computationally expensive to check every user’s location(s) and see if they fall within a given polygon. While this seems pretty basic in concept, the steps, and math to determine this situation in software is not that fast, particularly when it is necessary to do the same calculation millions of times. To take advantage of the polygon, we convert the polygon into a serious of rectangles (tiles). We assign each user’s location(s) to a tile and then check quickly to see if a user’s location is one of the tiles covered by the warning.
WDT also issues alerts on lightning strikes. We monitor a radius around a location for each end user location by the use of tiles. As an anecdotal measure of the speed of our alerting system, WDT has been told and also witnessed that users will see a lightning strike not far away and then receive their alert on their mobile app before they hear the associated thunder.
WDT’s Weather Radio and WeatherOps mobile app provide severe weather alerting that you need to understand your weather risk. If you personally, or your company, needs severe weather alerts, you should consider these apps. They can become your go-to apps for alerting weather services. If your company needs a solution for an app or as part of a full weather risk management solution, we can do that too. There’s an app for that, and we have it. You should work with a company that has the experience, patented technology, and scale to get information to the right people very quickly when it matters most.