Here & Now

From "The Cave" We Look At How The UW Tracks Hurricanes

Frederica Freyberg:

Now to science news and the role UW-Madison scientists play in hurricane forecast and research. Even though Wisconsin is 1500 miles away from Caribbean pathways of a hurricane, the UW plays a key part in the study and forecasting of those storms. I caught up with member of the UW Tropical Cyclone Research Group Derrick Herndon who works in the Space Science Lab, a space they call “the cave.” I started by asking what they’re tracking at the moment.

Derrick Herndon:

Currently we’re tracking Hurricane Maria. So Maria just made landfall on Puerto Rico. And then exited the coast of Puerto Rico and is now passing north of Hispaniola as a category 3 hurricane. This was a category 5 hurricane. It’s weakened some to a category 3. But it’s forecast to continue to the northwest and pass just to the east of the Bahamas before it moves north into the Atlantic

Frederica Freyberg:

In seasons like this, do people get hurricane fatigue?

Derrick Herndon:

I think you get a little hurricane fatigue. When the hits kind of keep coming you know. I know a lot of people in Texas were concerned that their story was basically being lost because it was followed very quickly by Irma, which was a deadly hurricane and damaging hurricane in Florida. So it can be very difficult in terms of moving resources to the right places because we have so many storms making landfall and impacting land and people’s lives.

Frederica Freyberg:

And yet you said this isn’t necessarily an unusual season?

Derrick Herndon:

It's not unusual so much in the terms of we’ve had some very strong storms this season. And we’ve had quite a few of them. We could go back to 2005, which wasn’t that long ago to a season where we have five category 4 or stronger storms. This season has set some records. Hurricane Irma did set the record for the strongest hurricane ever in that part of the Atlantic. And we’ve also seen some storms that have undergone some fairly rapid intensification. And we’ll need to go back at the end of the season to analyze that data.

Frederica Freyberg:

What’s responsible for that?

Derrick Herndon:

The main culprit really in this season’s activity is the waters are very warm. The waters in most of the Atlantic are actually a little bit above normal in terms of their temperature. The upper level environment is also very favorable. So just about all the disturbances that have had a chance to develop have become hurricanes or very strong hurricanes. Some of that is due to short-term time scales. And there’s also a bit of a climate component in there as well.

Frederica Freyberg:

So that does make people think about climate change?

Derrick Herndon:

Yeah, I think it definitely does. And I’ve had a number of questions from friends and colleagues and stuff about how does this fit within that perspective? The answer is we think with the warmer ocean, we should see stronger storms. And the probability of rapid intensification should be higher.

Frederica Freyberg:

How important is rapid intensification when we’re talking about places along the U.S. coastlines where there’s big populations?

Derrick Herndon:

That’s one of our biggest concerns. So it’s kind of a bit of a nightmare scenario in terms of a storm that is a fairly weak storm but then becomes a strong storm very close to the coast. So we don’t have a lot of lead time in terms of our forecast. Harvey is a bit of an example in that case. It went from a tropical storm to a category 4 hurricane in only 36 hours. When you consider we’re going to issue a hurricane watch 48 hours out, that gives us very, very little time to evacuate the coastal communities.

Frederica Freyberg:

And the satellite imagery that you work with here to track and forecast these kinds of storms, what application does that have? I mean, who uses it?

Derrick Herndon:

One of the direct users of this data is the National Hurricane Center. They use our satellite data and the products we can derive from the satellite data. So information about what is the environment that the hurricane is developing in. Are the upper level winds favorable? Is the water warm? Is their ample moisture for the hurricane to use? And we have products developed here at UW that can basically derive those perimeters and the Hurricane Center can look at the data and determine if the environment is favorable for the storm.

Frederica Freyberg:

Was this technology really started here at UW-Madison?

Derrick Herndon:

Yes, some of it was. The wind features that are derived from the satellite imagery was a product directly developed here.

Frederica Freyberg:

And the technology you’ve described has really made huge strides in the past decade. You can do things now and understand things now that you wouldn’t have been able to 10 years ago?

Derrick Herndon:

Yes, that's very true. We’ve basically cut our forecast track errors in half over the last 15 years. For example, a 72 hour forecast would be off by 100 miles 15 years ago. Now it’s off by 50 miles. That’s substantial improvement. Unfortunately some of that’s been offset a little bit by the fact that we need longer and longer lead times to evacuate because there are more people to evacuate and more people know the coast.

Frederica Freyberg:

You had some other things that you were showing on the screen as well, showing the eye.

Derrick Herndon:

Right. One of the things we’ve been working on recently is while we’ve made great strides in forecasting where hurricanes will go, our ability to forecast the intensity of storms has not kept pace. We have not made substantial improvements there. This particular product is a product developed here. It takes satellite imagery in the microwave spectrum and morphs that imagery into an animation. And basically we can look at the internal changes of the structure of the storm. In this particular case Maria is crossing the Caribbean and is undergoing what we call an eyewall replacement cycle, where the small inner eye is replaced by larger outer eye. And that has implications for the short-term forecast. So the Hurricane Center can use that information to improve their forecasts.