Hurricane Harvey was a watershed moment for extreme weather modeling. Operational models made some accurate predictions – storm path, flooding potential – but critically, all of the operational weather models failed to predict Harvey’s rapid intensification into a Category 4 hurricane, instead predicting landfall as a Category 1. A team of researchers at Penn State have revisited this historic shortcoming of modern weather forecasting, leveraging cutting-edge satellite and data assimilation technologies to learn from the past and prepare for the future.

The Penn State research, led by distinguished professor of meteorology and atmospheric science Fuqing Zhang, hinged on data from the GOES-16 satellite and Penn State’s “all-sky” radiance method, which earned its name by way of its ability to collect data in any weather – even in clouds or rain. GOES-16 only became fully operational in 2017, making Hurricane Harvey the first hurricane on which it captured data.

The researchers dove into the GOES-16/all-sky data through “hindcasting” – attempting to accurately “forecast” an event ex post facto using improved data processing. After combining the data with a model developed at the National Center for Atmospheric Research, the researchers found that assimilating the all-sky radiance data did a better job at reproducing cloud intensity and patterns compared to current models – both useful in forecasting the eye of the storm and its surroundings.

When the researchers tested models with and without the newly assimilated data, it created images that were almost identical to actual satellite images captured during Hurricane Harvey, representing a remarkable improvement over the operational models that were in use at the time. Of course, this is just the first step in getting new techniques ready for new operational models – a process that can take several years.

“This is still experimental,” Zhang said. “We have demonstrated that we can improve the track, position, intensity and structure of this particular event. We still need to study all other hurricane events with new satellite data but this gives us a lot of promises for the future of hurricane forecasting.”

Sadly, Zhang passed away in July – but his work is being carried on by his fellow researchers at Penn State.

“We will continue to test our satellite data assimilation system with more hurricanes to see if this method works well with other severe weather events,” said Xingchao Chen, an assistant research professor. “In addition to all-sky infrared radiances, we are beginning to look at microwave radiances, which effectively penetrate cloudy regions.”