Hurricane Harvey has dumped so much rain on Houston and the coast of Texas that the National Weather Service was forced to adopt new colors to map it accurately.
This is the first time the NWS has added new gradations to a graphic in this way. But other meteorologists have recently added new colors to represent severe heat as well. As climate change brings more extremes in temperature, rainfall, and other types of weather, meteorologists will need to look toward new types of information design. Lightly modifying traditional weather visualizations only normalizes the abnormal. We need entirely new graphics to help us understand the scope of these extremes–and help us be better prepared to face them.
Currently, meteorologists are adding onto the legends of existing weather maps–which were popularized in the early 20th century–to accommodate new records. Because of the incredible amount of rainfall in Houston–16.7 inches on Sunday alone–the NWS decided to add colors to the map that would represent rainfall greater than 20 inches. While the original map had simple dark purple for 15 inches or more of rain, the new, more accurate version of the NWS’s graphic uses dark purple for 15 inches to 20 inches, plum for 20 inches to 30 inches, and a light pinkish lavender for more than 30 inches. The storm dumped about 2 feet of rain over the weekend, and the total rainfall could reach 50 inches by the end of the week–about the same amount of rain that Hawaii receives in a year.
— NWS (@NWS) August 28, 2017
“The tremendous rainfall in Texas is literally and figuratively off the map,” an NWS spokesperson told Co.Design in an email.
In 2013, Australia’s Bureau of Meteorology faced a similar problem–parts of the country were so hot that temperatures were quite literally off the scale. The bureau’s solution? Add bright purple and hot pink to the map to indicate temperatures between 125 degrees and 129 degrees Fahrenheit (between 52 degrees and 54 degrees Celsius).
The Bureau of Meteorology have added extra colours to their temperature scale for next week: 54°C! pic.twitter.com/x4eLIFQh
— NationalScienceWeek (@Aus_ScienceWeek) January 8, 2013
And earlier this summer, meteorologists in Arizona had the same problem and came up with the same solution: adding more colors to the temperature map.
— Mark Torregrossa (@weathermanmark) June 21, 2017
But these subtle changes to weather maps don’t go far enough in conveying how unprecedented this weather is. If people are to be well-informed about the weather and how it could impact their lives, they need to understand its context–something adding colors to a map won’t convey.
So what could weather visualizations that incorporate extremes look like? Perhaps they aren’t maps at all. Some of the best weather data viz of 2017 so far has looked at weather in a historical context, like this circular temperature map. Perhaps maps could provide points of comparison, like this map that projects what winters and summers will feel like in the year 2100. Or perhaps even greater detail is the way to go. As climate change brings more extreme weather, we’re going to need information design to catch up.