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Advanced Dvorak Technique expected to improve tropical forecasts

Technique gauges tropical cyclone intensity
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Posted at 7:45 PM, May 27, 2022
and last updated 2022-05-27 20:28:04-04

TALLAHASSEE, Fla. (WTXL) — Modern satellites can give forecasters a view of tropical systems as they develop with more detail than ever before.

This year, forecasters at the National Hurricane Center will have access to a more powerful satellite-based technique for determining storm intensity. That software upgrade will help them save lives.

Upgraded software called the Advanced Dvorak Technique (ADT) is helping satellites see more clues in tropical systems from thousands of miles overhead.

“It’s one of the best ways to get the intensity estimate when there is not an aircraft available,” explained Tim Olander. He is a researcher at University of Wisconsin-Madison. “If we can improve the current intensity estimate, we can improve the numerical models moving forward.”

Those models show us where weather could get bad. They get that estimate using ADT. Olander said it’s a method that began decades ago.

“It was just pattern matching, looking at the tops of clouds and looking at their temperature structure and the structure of the rotation of the storm,” Olander said.

Modern technology builds on the manual technique developed in the 1970s by National Oceanic and Atmospheric Administration researcher Vernon Dvorak. This year, it is getting an upgrade within NOAA’s operations.

This tech is just part of a toolbox that already uses data gathered from the so-called hurricane hunters. The 53rd Weather Reconnaissance Squadron is a component of the 403rd Wing located at Keesler Air Force Base in Biloxi, Mississippi.

“I’ve seen some big storms in the Atlantic,” said Lieutenant Colonel, Mark Withee. “I’ve flown a lot of gulf storms.” Withee said he has been flying into these storms for 7 years. “We estimate there’s typically a 20 to 30 percent improvement in the reliability of the forecasts with the data we provide.”

That reliability has improved significantly in the nearly 30 years since Hurricane Andrew devastated South Florida as a category five storm.

“Andrew was a remarkable storm,” said Dr. Mark Bourassa. He is a professor of meteorology at Florida State University. “We have better remote sensing. Better aircraft observations. We know how to use the data better in models.”

The National Hurricane Center says this year, with improved modeling, the forecast cone on maps will shrink up to 6 percent smaller in the 12 to 96-hour timeframe. Data shows forecast errors at 48 hours out have dropped from nearly 200 nautical miles in 1992 when Andrew hit to just 50 nautical miles in 2021.

“If you’re a homeowner, it’s worth paying attention to these things and preparing if you need to prepare,” Dr. Bourassa said.

Olander said the upgraded Dvorak Technique can give forecasters a better idea of how a storm is developing.

“Because they have better estimates at the beginning of the storm, they can use that to improve their forecast going forward. That includes not only intensity but position of the storm,” Olander said.

ADT was developed by researchers at the University of Wisconsin–Madison Cooperative Institute for Meteorological Satellite Studies.