A New Tool For Storm Modelers

A New Tool For Storm Modelers

By Daniel Hays

NU Online New Service, March 21, 11:24 a.m. EST?A weather researcher with a catastrophe modeling firm said he has uncovered a weather phenomenon similar to El Ni?o that can help predict Atlantic Coast Hurricane attacks.[@@]

Steve Smith, vice president of ReAvisory in Chicago--a part of the Carvill reinsurance intermediary firm--said his study appears to solve the riddle of why in 2003 only one of 13 hurricanes that blossomed in the Atlantic basin hit the U.S. coast.

Conversely, it would also explain why Florida was struck four times by major hurricanes last year.

The key, said Mr. Smith in a recent report, is the action of the Bermuda High, which can function like a "goalkeeper"?deflecting hurricanes away from the U.S. East Coast. In 2004, he wrote, "the goalkeeper was out of position, allowing hurricanes through!"

Normally, according to Mr. Smith, you expect 20-to-30 percent of Atlantic basin hurricanes to make landfall against the Atlantic Coast, but this has not always been happening.

His study of the weather data, he wrote, points to an "unusually persistent weather feature off the U.S. coastline" that has protected the East Coast.

"This feature is an intersection of the Bermuda High pressure system and the U.S. continental low. The persistence of this pattern has caused hurricanes moving north-west towards the U.S. East Coast to curve upwards towards the Northeast before making landfall."

Mr. Smith--using surface pressure data from the National Atmospheric Administration archives--has constructed what he calls a Bermuda High Index (BHI). The researcher said his BHI compared readings from Bermuda International Airport and Atlanta Hartsfield International Airport.

His findings come, he wrote, when the Atlantic basin is in a period of enhanced activity for the next 10- to-40 years.

In an interview Mr. Smith said that the Bermuda High can be forecast five-to-10 days out, and as such can improve short-term warnings of a coastal strike.

His report found that "registering the position, presence or absence of the Bermuda High alone provides strong indication on the potential for landfalls for those hurricanes."

Unfortunately, use of the Bermuda High data for long-term seasonal predictions appears slim because it is not directly related to changes in Atlantic sea surface temperature, which makes its vagaries beyond current scientific understanding, Mr. Smith reported.

He is hoping that further research into high movement linked to North Atlantic Oscillation--variability in the atmosphere over the North Atlantic?will improve use of Bermuda High as a long range forecasting tool.