THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: Friday, August 12, 1994 TAG: 9408120787
SECTION: LOCAL PAGE: B01 EDITION: FINAL
SOURCE: BY STEVE STONE, STAFF WRITER
LENGTH: Long : 102 lines
If one of the nation's leading hurricane forecasters is correct, this will be a quiet year for tropical storms in the Atlantic.
William Gray, a professor of atmospheric sciences at Colorado State University, predicts there will be seven tropical storms this year, with four of those becoming hurricanes and just one developing into an intense hurricane.
That compares with an annual average of 9.2 tropical storms, of which 5.7 become hurricanes, based on data going back to 1950.
Gray has emerged as a leading expert on the global climatic formulas that mix weather and other environmental factors he says generate hurricanes.
His early research met with skepticism from many meteorologists who scoffed at the idea that anyone could forecast hurricanes, especially given the complexities of arriving at an accurate five-day local forecast.
While he still has detractors, Gray has won increasing respect as he has refined his forecasting methods and achieved what many thought impossible: accurate forecasts of the number of tropical storms and hurricanes.
In November of 1991, for instance - seven months before the 1992 hurricane season began - Gray predicted there would be four hurricanes and 15 hurricane days, or 24-hour periods with hurricane conditions. There were four hurricanes and there were 15 3/4 hurricane days.
He forecast one of the four would be severe. Again, he was correct. Hurricane Andrew slammed South Florida before swinging across the Gulf of Mexico to Louisiana and becoming one of the most destructive natural disasters in U.S. history.
For this year, Gray had earlier predicted five hurricanes, but he dropped that prediction to four in his revised forecast issued Aug. 5.
If he is on target, that would extend an unusual number of consecutive years with minimal tropical-storm activity that began in 1991. But, he cautioned, it takes only one hurricane to create disaster.
``There's no way to tell wherethe individual storms are going to go,'' Gray said. ``Even though this is a below-average year . . . they all could come over the U.S. coastline.''
Gray based his 1994 prediction on high barometric pressure readings in the Atlantic Ocean and the Caribbean Sea, combined with a drought in the Sahel region of West Africa and strong easterly winds in the upper atmosphere. Those are three of five factors he considers in making his forecasts. The others are temperature and barometric pressure readings in West Africa and the influence of El Nino, a warm Pacific Ocean current.
Although his forecasts are still experimental and his methodology is modified as he learns more, Gray's record since he started issuing forecasts 10 years ago is strong.
Six of his forecasts (1985, 1986, 1987, 1988, 1991 and 1992) were quite accurate, two (1984 and 1990) were marginally correct and Gray himself labeled his 1989 and 1993 forecasts as failures.
The key component in Gray's forecast is El Nino. The warm Pacific current usually flows along the western edge of South America, near Ecuador. Every seven to 10 years, however, it extends its coastal flow south along Peru.
During years of moderately warm or very warm El Nino, there is a decrease in hurricane activity in the Atlantic. It was the unexpected, continuing strength of the current last year that Gray cited in explaining the admitted failure of his 1993 forecast.
In June 1993, Gray had anticipated seven hurricanes for the year. He reduced that to six in his revised outlook in August. There were only four hurricanes, however.
This year Gray expects El Nino to be a neutral factor.
``The El Nino is surprising all of the experts out there in that it remained warmer than normal for three consecutive years,'' Gray said. ``It hasn't done anything like this for more than 50 years.''
El Nino now is in a slight warming pattern, but ``we believe it will be a neutral player instead of a force to suppress hurricane activity,'' Gray said.
The Atlantic hurricane season began June 1 and will end Nov. 30. The most active months are usually August and September.
The 1994 outlook is ``quite a bit below the long-term average and this will be the fourth straight year we've had a below-average season,'' Gray said. ``So it's unusual. You have to go back many, many years before you can find four consecutive years with below-average hurricane seasons.''
Gray believes the trend will end. ``We should see a return to more active seasons, but we don't know when this will take place,'' he said.
His bet, however, is that we are at the end of the respite.
``It is anticipated that the 1995 hurricane season will be much more active than have the hurricane seasons of 1991-1993 and the expected activity of the 1994 season,'' Gray said.
Thus far, there has been only one tropical storm in the Atlantic this year strong enough to be named. It was called Alberto. Here are the other names slated to be used in 1994: Beryl, Chris, Debby, Ernesto, Florence, Gordon, Helene, Isaac, Joyce, Keith, Leslie, Michael, Nadine, Oscar, Patty, Rafael, Sandy, Tony, Valerie, William. MEMO: To hear comments from William Gray and for tropical storm updates,
call INFOLINE at 640-5555 and enter category 1237.
ILLUSTRATION: Staff chart by STEVE STONE
HURRICANE FORECASTS
Source: William Gray, Colorado State University, Fort Collins, Co.
For copy of chart, see microfilm
KEYWORDS: WEATHER HURRICANES
by CNB