Severe storm warnings receiving makeover
We’ve all heard them — the blaring alerts that activate our cellphones or television when a severe weather warning is issued.
Perhaps our favorite weather app sent us a push notification, or we saw a television meteorologist pointing at vibrant boxes on a weather map. Whatever the medium, weather warnings have a way of finding us, especially whenever a severe thunderstorm is close by. Now, those warnings, specifically the way in which they’re generated, are in the process of getting a makeover.
Severe weather warnings are issued for individual thunderstorms; before 2007, entire counties would be alerted at once. Over the years, weather warnings have become more targeted — but one warning can still cover an expansive area. Moreover, conditions can vary wildly even within the region enclosed by a single warning.
Now, the National Weather Service is hoping to change that.
Kodi Berry leads the program that’s updating warnings at the National Severe Storms Laboratory (NSSL) in Norman, Okla. The Forecasting a Continuum of Environmental Threats program, or FACETs, is an endeavor the National Weather Service is pursuing to communicate the hazards posed by severe thunderstorms on a hyperlocal level.
Berry says the goal is to provide a more continuous flow of information for those who need it the most.
According to the National Severe Storm’s Laboratory, FACETs aims to improve weather watches and warnings to provide “detailed hazard information through the use of ‘threat grids’ that are monitored and adjusted as new information becomes available.”
Typical weather warnings are issued in the form of polygons digitally drawn on a map. If you’re within the polygon, you’re alerted and urged to take action — such as seeking shelter. But just a stone’s throw away, a neighboring home outside the polygon may not be given any special instructions. The current state of weather warnings is binary, akin to a “yes” or “no” to severe weather.
Berry’s team is hoping to improve that by creating a product that reflects the gray area in between. They are experimenting with displaying probabilities to reflect the range of possible outcomes in a rapidly-evolving severe weather event.
“There has been a lot of social science research that shows that, given probabilistic information, people make better decisions,” Berry said. “If we appropriately define these probabilities and what they mean, people can use them to make better decisions.”
An example? Imagine you work in a nursing home 20 miles downwind of a tornado-producing thunderstorm. An existing tornado warning only extends 15 miles downstream, so you’ re not under a warning — yet.
But you know it takes half an hour or more to move all the residents to shelter. Do you start now? Or do you wait until a warning is (or is not) issued?
Berry’s team found that the one-size-fits-all binary nature of warnings doesn’t necessarily fit all consumers. “Some people may need a little more time than what the warning provides,” Berry said. “They may have a lower personal probability threshold.”
Adding probabilities will not replace existing weather warnings, but rather offer more context for people around the warning itself. The probabilities will be assigned on a grid map, much like most weather forecasts, and will update by the minute in real time.
Probabilities will be greatest along the center of the storm’s predicted path, diminishing radially outward as well as farther downwind. Berry’s office compares the so-called “plume” to the probabilistic wind speed graphics issued by the National Hurricane Center.
Severe thunderstorm and tornado warnings themselves are getting an overhaul, too. Warnings will now “move” with storms, growing downwind if a storm looks to hold together. The back edge of the warning will “drop out” behind the storm, too — akin to an “all clear” message once the danger has passed.
The warnings themselves will also be updated more frequently.
Berry estimates these changes could take up to 5 years to implement.