More tools, better forecasting

determining strength and location of tropical cyclones is important

The hurricane above is pretty straight-forward -- clearly with that eye we have a well-formed intense tropical cyclone. But just how strong are those winds? And look at the tropical storm below which was determined to be a tropical storm:

This was in the Arabian Sea

Exactly where is the center and how strong is it?

These questions of location and intensity continue to be vital in forecasting hurricanes. The strength of a storm tells us all what to prepare for and the location tells us where the storm is and is going. And do we even have a tropical storm or not? To the question of development and intensity, back in May 1975 Vernon Dvorak introduced a technique using a cloud chart to determine both the stage a storm was in and how strong it appeared to be:

courtesy NOAA

Dvorak compared cloud features such as the eye, cloud cover, circulation and rain bands to determine a T (for tropical) number. This T number could then be referenced on a chart yielding an estimated top wind speed and lowest pressure. He also had a way to estimate intensity change by noting the changing of the clouds.

In 1975, this technique was limited to daytime satellite pictures but since then IR satellite information which we get all the time has been integrated into the technique. Of course, computers have upped the game considerably. The Dvorak technique is still the best way to determine what and where development is occurring, especially since you can’t fly hurricane hunters into a storm all day every day (and most ocean basins don’t even have hurricane hunters).

Improving Dvorak

You may have read the CNN article over the weekend that a new improvement to the technique is ready for 2022. From the University of Wisconsin, researchers have come up with what they coined ARCHER: Automated Rotational Center Hurricane Eye Retrieval. In other words, where is the center of the storm and how strong is it? Without elaborating, the scientists say they will be incorporating even more satellite data now available into the program.

Given that all forecasts I’ve seen for the 2022 season have us as busy as last year, this new information has arrived just in time! You can read the full CNN article right here.


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About the Authors:

KPRC 2's chief meteorologist with three decades of experience forecasting Houston's weather.

Amanda Cochran is an Edward R. Murrow award-winning journalist. She specializes in Texas features, consumer and business news and local crime coverage.