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Posted at 10:15 AM ET, 08/24/2012

As Isaac threatens the RNC, a look at how far hurricane forecasting has come


The stage and podium for the 2012 Republican National Convention are unveiled earlier this week in Tampa, Fla. (AP Photo/Scott Iskowitz) (Scott Iskowitz - AP)
The last time a major political party held its convention in Florida, the art of hurricane prediction was far more limited than today. Luckily for the Republicans and Democrats—who both held their conventions in Miami Beach in 1972—no hurricanes crashed the parties. In fact, there were only four named storms that year.

Today, we’re in a multidecade stretch of increased hurricane activity, and the GOP convention in Tampa next week faces a wide spectrum of possible disruptions from a strengthening Tropical Storm Isaac.

There’s no way to know exactly if or where Isaac will ultimately make landfall in the United States or how strong it will be. Even a close call in Florida could result in flight cancellations, heavy rains, and other convention complications. The good news is that forecasters now have a wealth of tools and an array of knowledge at their disposal that were almost unimaginable 40 years ago.

At times like this, when the plans of thousands of conference-goers hang in the balance, it’s worth noting that the nation’s long-term investment in meteorological research has led to a marked improvement in hurricane guidance.

More notice. Consider that in 1972, official forecasts from NOAA’s National Hurricane Center extended out only three days versus today’s five days. The skill of those forecasts was also well below our current level. The average 48-hour error in track forecasts was around 300 miles in the early 1970s, compared to around 100 miles today. In large part, that’s due to a wider range of computer models and ensembles (the same model run multiple times, each time with slightly different initial conditions) that allow forecasters to gauge which paths are most likely.

Seeing deep inside the storm. Another major advance since the early 1970s is the advent of dropsondes, packages of weather sensors that are dropped by parachute from hurricane-hunter flights. Hundreds of these now–GPS-tracked dropsondes, designed at the National Center for Atmospheric Research and manufactured by Vaisala, are launched by NOAA and U.S. Air Force aircraft each hurricane season. The observations they collect on temperature, humidity, and winds are funneled into computer models, boosting their accuracy. This year through 2014, the Hurricane and Severe Storm Sentinel project is using the remotely piloted NASA Global Hawk aircraft to launch a new generation of dropsondes into the highest reaches of hurricanes and the steering winds that surround them. The study will help clarify the factors—both internal and external—that lead a hurricane to intensify.

Looking out to sea. When hurricanes are far at sea, satellites are our main source of information. In 1972, the first series of NOAA satellites was providing information on clouds through visible and infrared channels, but these were polar-orbiting satellites, which meant they passed over the tropical Atlantic only twice a day. Today, satellite imagery is collected as often as every 15 minutes above hurricanes. As a result, we now have a far better idea of the location and strength of developing systems.

Sorting out which storms will develop. Forecasters struggle to determine which of the many easterly waves that develop in the Atlantic each summer and fall will “make the grade” and develop into tropical storms. Scientists at several universities and agencies are now analyzing results from a major study called PREDICT, carried out in 2010, that focused on the differences between groups of scattered thunderstorms over the Atlantic that dissipated versus those that organized into potentially deadly named systems. Because it takes these easterly waves a week or more to cross the Atlantic, any advance in determining which ones pose the greatest threat could add several vital days to our window of awareness and preparation.


Hurricane Charley track forecast, August 2004 (National Hurricane Center)
Predicting landfall. It’s still very difficult to predict changes in hurricane intensity with confidence. In contrast, track forecasts are now quite accurate in the 12-to-24-hour window, but even small changes in track can make a difference if that track runs parallel to the coast. These issues were highlighted in 2004 with Florida’s Hurricane Charley. Its track shifted rightward in the few hours before landfall—just as the storm intensified from a Category 2 to Category 4, which led to major damage in southwest Florida. A post-storm study found that such changes in intensity could be quickly diagnosed by applying software developed at NCAR and the Naval Research Laboratory to data from coastal radars. This technique could alert emergency managers to fluctuations in intensity in the critical hours before landfall.

If the perfect crystal ball were in our hands, then the GOP convention planners would know exactly how to proceed. There’s still much work to be done, especially on changes in hurricane intensity. Yet our nation’s investments have clearly led to a sustained wave of forecast improvements, saving lives and property.

Another challenge will be maintaining or replacing the aging fleet of U.S. satellites. This decade could see a loss in capability, as noted by the National Research Council in a recent report. Already, the U.S. is collaborating more with other countries on satellite systems. That trend may continue even as efforts are made to restore and improve our own fleet of satellites.

NOAA is now leading a multiagency Hurricane Forecast Improvement Project. By later this decade, the project hopes to cut the average error for hurricane track forecasts in half and to successfully predict at least 90% of rapid intensity changes. By leading to landfall forecasts that are more specific and more confident, such advances would help bolster confidence in warnings while reducing the amount of coastline that needs to be placed under costly evacuation orders.

The private sector has been an important partner in this effort. In 1972, weathercasts on radio and TV were the main route by which NOAA hurricane warnings reached the public. Weathercasters remain critical to getting the word out. What’s new is that people can also access warnings and other details from public and private sources through smartphones and Web browsers. Even more progress is possible—such as better evacuation routing and more specific storm guidance via smartphones—as the public, private, and academic members of the weather enterprise work together.

With continued investment in research now underway and on the drawing board, we can look forward to a week’s worth of advance notice on how a potential hurricane threat may evolve. That means the next time the Republicans or Democrats hold a convention in hurricane country, they could have the benefit of more time, if needed, to implement a Plan B.

Meteorologist Robert Henson is a writer and editor at the University Corporation for Atmospheric Research, which operates the National Center for Atmospheric Research

By Robert Henson  |  10:15 AM ET, 08/24/2012

Categories:  Latest, Tropical Weather, Science, Technology

 
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