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Forecasting Storm Track, Intensity Can Be Difficult

Miami Herald
This forecast made on Aug. 26 showed Ericka hitting South Florida on Monday. The storm died out after going over Hispaniola and brought some rain to South Florida but did no major damage.

Even with all the radar technology that's available, it's hard to predict what any storm will do (i.e. Hurricane Jeanne). Let's face it, mother nature is not easy to predict.

Erika, which threatened South Florida last week,  was frustrating to forecasters because it didn't want to behave the way some models had pegged it. But, that's not completely unusual according to James Franklin. He oversees forecasters at the National Hurricane Center. 

What about Erika made it hard to forecast? 

Erika was dealing with some strong upper westerly winds in the atmosphere that were trying to separate the circulation at low levels from the thunderstorm activity in the upper levels. Trying to predict how the storm would stay together vertically was a challenge. In the end it didn't stay together and fell apart when it came to Hispaniola.

Forecasting storms has improved significantly in the last six years.

Track forecasting has actually been improving for a long time. You can go back to the 1970s and our track forecast has been getting better decade by decade. Despite our problems with Erika we expect that to continue to happen. The improvement in track forecasting is due to a couple of  things. We have faster computers that allow us to produce models that can see more and more detail in the atmosphere. And we're feeding those models more information, mostly from satellites as they collect storm information.

There was a project in 2009 that helped improve forecasting storms significantly. What was it?

The Hurricane Forecast Improvement Project, or HFIP, began in 2009.  It's been a wonderful program. It's been the most serious application of research dollars to hurricane modeling that I've seen in my 30-plus-year NOAA career. It's finally starting to pay some benefits. We've seen one of our models, the Hwrf(pronounced H-warf) model, start to give us more accurate intensity forecasts, and we've gone many years before HFIP without a lot of improvement in intensity forecasting.

There were cuts though to program  within the last year.

There were some budget cuts. It had been funded at about 14 million, 15 million dollars a year, which in our business is a lot of money. That was cut to less than 5 million dollars this year. So that jeopardizes some of the improvements that we hope to get in the years to come. Certainly progress will be slow if that program is not fully funded.

That sounds like a significant cut to the program.

We would like to see resources applied to our problem. We want to make the best forecasts that we can. So, this H-FIP program has been good to us and we would like to see that continue. Obviously we will do the best job that we can every time, regardless of what resources are thrown our way.

Are the challenges you faced forecasting Erika at all comparable to forecasting a storm like Katrina?

Katrina in a lot of ways was much simpler. Strong hurricanes, category three, four or five hurricanes, are far easier to predict than tropical storms or tropical depressions. Hurricanes exist in environments that are much simpler. A hurricane doesn't get to be strong unless the environment is much simpler. When you have a complicated environment like Erika with the winds at low levels blowing at different directions than the winds at the top part of the atmosphere, that makes it much harder to forecast. The four- and five-day forecasts for most storms, have a fairly high degree of uncertainty associated with them. And those cones (of uncertainty) do move. 

Help us understand the challenge you face in forecasting storms, how you deal with uncertainty and how those cones work.

There are a couple things to know about the cone and the forecast. Our average five-day forecast area is almost 250 miles. The average four-day area is almost 200 miles. So anyone who is looking at that cone and expecting it to be perfect four or five days in advance is going to be disappointed more often than not. Sometimes those forecasts are very good. But in some situations, like Erika, where we're not sure how the storm is going to hold together, those are the cases where we can have significant errors. The other thing about the cone is that it's designed to encompass the track of the storm about two-thirds of the time. So that means about one-third of the time the storm will track outside of the cone. The cone also doesn't tell you anything about impacts.

Credit NOAA.org
NOAA's Aircraft Operations Center maintains and operates a fleet of 12 scientific research, reconnaissance and surveillance aircraft that directly support the varied programs of NOAA. These aircraft enable scientists to precisely observe, measure and chart the dynamics of a storm. This is the NOAA WP-3 Orion turboprop Hurricane Hunter aircraft.

Luis Hernandez is an award-winning journalist and host whose career spans three decades in cities across the U.S. He’s the host of WLRN’s newest daily talk show, Sundial (Mon-Thu), and the news anchor every afternoon during All Things Considered.
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