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 firmsaid he has uncovered a weather phenomenon similar to El Ni?o thatcan help predict Atlantic Coast Hurricane attacks.[@@]

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

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

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

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

His study of the weather data, he wrote, points to an "unusuallypersistent weather feature off the U.S. coastline" that hasprotected the East Coast.

"This feature is an intersection of the Bermuda High pressuresystem and the U.S. continental low. The persistence of thispattern has caused hurricanes moving north-west towards the U.S.East Coast to curve upwards towards the Northeast before makinglandfall."

Mr. Smith--using surface pressure data from the NationalAtmospheric Administration archives--has constructed what he callsa Bermuda High Index (BHI). The researcher said his BHI comparedreadings from Bermuda International Airport and Atlanta HartsfieldInternational Airport.

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

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

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

Unfortunately, use of the Bermuda High data for long-termseasonal predictions appears slim because it is not directlyrelated to changes in Atlantic sea surface temperature, which makesits vagaries beyond current scientific understanding, Mr. Smithreported.

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