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Wednesday, October 17, 2001



Weather service
streamlines surf
warnings

Wave heights now will be based
on the front of the wave


By Helen Altonn
haltonn@starbulletin.com

High surf advisories and warnings will be standardized starting Oct. 30 to reduce injuries and deaths due to surf -- Hawaii's top natural-hazard killer.

This is among changes being made in surf and flood warnings, officials of the National Weather Service's Honolulu Forecast Office said yesterday.

Tom Heffner, warning coordination meteorologist, said high surf advisories and warnings will be issued in two tiers -- one for high surf dangerous to swimmers and beach-goers, the other for high surf that may threaten life and property.

He acknowledged some pockets of resistance by lifeguards but said the weather service is working with them to base all observations on the height of the face, or front of the waves, from trough to crest just before the waves break.

County Civil Defense agencies and water safety organizations cooperated with the weather service on the new program and approved the wave height criteria for advisories and warnings, he said.

Forecasters not only will report true wave heights but will try to increase the lead time for high surf advisories and warnings, said Jim Weyman, meteorologist-in-charge of the Forecast Office and Central Pacific Hurricane Center director.


New high-surf measures

Effective Oct. 30, the National Weather Service will switch to a new system for high surf advisories and warnings around the state. The surf heights reflect the face value, or the height of the front of the wave (trough to crest) before the wave breaks.


High surf advisory High surf warning

North-facing shores 15 feet 25 feet

West-facing shores 12 feet 20 feet

Big Isle west shores 8 feet 12 feet

South-facing shores 8 feet 15 feet

East-facing shores 8 feet 15 feet


The goal is to report high surf warnings 12 hours in advance, he said.

Kevin Kodama, senior service hydrologist, described changes being made nationwide to standardize reports for possible flooding and to avoid confusion.

They will go into effect next month on the mainland but they were initiated here Oct. 3 because November traditionally is Hawaii's most active flash-flood month, he said.

The changes are being made to improve public safety, the officials emphasized.

Heffner said various methods were used in the past for surf measurements, such as estimating the size of the back of waves. Surf reports, as a result, were one-half to two-thirds less than the real wave heights.

New criteria was established for high surf advisories and warnings based on data collected by Rick Grigg, a University of Hawaii oceanographer and member of the Governor's Beach and Water Safety Task Force.

Grigg said the old way of measuring surf was from the face value, but lifeguards over the years invented a new system of measuring waves from the back.

He said Duke Kahanamoku's famous 1.1-mile ride near Castles had to have been more than 20 feet when the wave first broke, but today's surfers would have called it 10 feet if they had been there.

The tendency to underestimate waves and keep the surf a secret developed slowly from the 1950s to 1970s, Grigg said, noting fewer people would show up to surf if the waves were small and lifeguards would have the ocean to themselves.

Surf numbers at the high end wouldn't change because of a "fear factor," Grigg said. "At 25 feet, almost everybody is afraid, so they call it as it is."

But "the macho factor kicks in" when 15-foot waves are reported at 10 feet and 10-foot waves at 5 feet, he said.

The task force recognized the need to call the true height of the waves after a number of lawsuits were filed in the 1980s and 1990s by people who were severely injured because shorebreak waves were larger than reported, he said. Several cases were won or settled for millions of dollars, he said.

Heffner said, "The message is that we are all working together on this to make sure information going out to everybody -- tourists and surfers -- is the same so they don't get waves they didn't expect."

For high surf warning criteria, a threshold of 25 feet was set for north-facing shores and 20 feet for west-facing shores, except for 12 feet on the Big Island's Kona side. This reflects a conservative threshold for surf that may threaten life and property, Heffner said.

Among changes to flood forecasts, the weather service has replaced "Flood Potential Outlook" with "Hydrologic Outlook" when heavy rains and flash flooding are possible in 36 to 72 hours.

Kodama said the "Hydrologic Outlook" will also be used to report dry patterns or drought.

A "Flood Watch" will be issued instead of a "Flash Flood Watch" when flooding is possible within 36 hours and updates will be issued at least every 12 hours.


Deadly waters

Ocean-related deaths in Hawaii from 1993 to 1997, the latest years the data are available:

Oahu 101

Big Island 54

Maui 42

Kauai 31

Molokai 6

Lanai 4


A "Flood Statement" will be issued to cancel or supplement a "Flood Watch" with rainfall and other reports. This replaces the former Urban and Small Stream Advisory and Flood Advisory for the Big Island.

The "Flash Flood Warning" is the same and will be canceled by a "Flash Flood Statement."

Looking at Hawaii's weather in the months ahead, Heffner said, "We're still in a neutral pattern," adding that the winter season outlook will be issued by weather service climatologists in two days and he doesn't expect near-normal conditions to change.



Source: State of Hawaii Department of Health Injury and Prevention and Control Program



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