Neil Frank disputes ‘questionable’ storm counts

Sun-Sentinel, 1/2/2008

A well-known name in hurricane-forecasting circles Neil Frank is challenging how the National Hurricane Center classifies storms. Last year, he contends, six of the 15 named systems may have been too weak to really deserve tropical storm status. ‘They’re questionable,’ said Frank, the hurricane center’s director from 1974 to 1987 and now chief meteorologist for KHOU-TV, the CBS affiliate in Houston.

Though it might seem he is trying to upstage the hurricane center, his real intent, Frank said, is to dispute that global warming has led to more active Atlantic tropical storm seasons, as several meteorological studies have asserted. Over the past decade, Frank maintains, numerous systems were classified as tropical storms and hurricanes that probably didn’t warrant that status.

Winnow out those systems from the annual lists, and present-day tropical weather may be no more intense than in the past, he says. ‘The historical records are not adequate to determine if global warming has affected number and strength of tropical systems,’ he said. The inflation in the number of named storms has come about, Frank says, because the hurricane center has adopted different and, in his opinion, looser guidelines on how storms are named.

Until the mid 1990s, the hurricane center relied on central barometric pressure as the primary yardstick of a storm’s strength. The lower the pressure, the stronger a system. Storms with readings of 1005 millibars or higher were deemed too weak to be named, Frank said.

If that standard were in place now, four of 2007’s storms, including Erin, Gabrielle, Ingrid and Melissa, would be disputable, he said. Two, Chantal and Jerry, would not have been named at all because both formed in the Atlantic well to the north of the tropical region, even though their central pressures were relatively low, he added.
Further, Hurricane Felix, designated a ferocious Category 5, would have been deemed ‘a strong Category 4,’ according to central pressure measurements, said Frank.
Then came a change in philosophy in 1996, Frank said. Forecasters started to place more emphasis on satellite imagery to calculate a storm’s sustained winds. Yet Frank maintains the central pressure method of naming storms is more accurate because with satellite imagery, forecasters estimate winds based on their reading of cloud patterns.

While Frank’s assertions may seem academic, they raise questions whether the hurricane center is too quick to give storms names. And the number of systems per year is important for historic records and spotting trends.

Those trends, in turn, are factored into how insurance companies set premiums for homeowner coverage, Tom Zutell, spokesman for the Florida Office of Insurance Regulation, said. Specifically, trends are entered into computer models as one of the elements that determines rates, he said. ‘That is one tool that insurance companies use,’ he said. ‘But it’s not the only tool that they use to actuarially arrive at rates they need to pay clients.’ At the National Hurricane Center, forecasters say if they’re finding more storms and hurricanes these days, it’s because they have new technological tools at their disposal. ‘Things have changed since Neil Frank’s era,’ said Chris Landsea, the center’s science and operations officer. ‘I would agree with him that we’re naming more now than we did then. But I would also argue we’re naming them correctly. We just have more tools to do it correctly.’ Among those tools: geostationary and polar orbiting satellites, which, in addition to providing detailed imagery, allow forecasters to pinpoint the strongest tropical-force winds as well the temperatures in the atmosphere around them, he said.

Hurricane hunter aircraft have been equipped with stepped frequency microwave radiometers, which provide an accurate reading of wind speeds near the ocean surface, he said.

Landsea said the hurricane center, which is in Miami-Dade County, uses strict guidelines to name storms. A system must have sustained surface winds of at least 39 mph, cannot be near a cold front to ensure it’s a ‘tropical cyclone, not a winter one’ and must have organized thunderstorm activity around its core. ‘If it has all of those, we name it,’ he said. At the same time, Landsea agreed with Frank that global warming likely isn’t responsible for the surge in tropical activity since 1995, notably during 2005, the busiest year on record with 28 named storms.

Landsea said it’s possible other eras and other years were just as active. He noted that in 2005, 17 systems made landfall. In 1933, previously the most active season on record with 21 named systems, 19 made landfall. ‘So if you just look at ones that made landfall, 1933 was busier,’ he said. ‘The years were probably fairly comparable in overall activity.’ Ken Kaye can be reached at kkaye@sun-sentinel.com or 954-385-7911.