THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Tuesday, February 14, 1995 TAG: 9502140275
SECTION: FRONT PAGE: A1 EDITION: FINAL
SOURCE: BY JAMES SCHULTZ, STAFF WRITER
LENGTH: Medium: 83 lines
Wondering where winter went in December and January? Or, now that it's back in full force in February, how long it will stay?
Part of the answer may literally lie an ocean away, in abnormally warm western Pacific waters. It's there that The Child has been growing since late spring. The next tantrum he throws might send coastal storms full of wind, rain or snow to claw at the Virginia and North Carolina coasts.
The Child, known more formally as the El Nino Southern Oscillation, occurs every two to five years when underwater disturbances churn warm Pacific water to the sea surface. As the ocean warms, so does the air above, which alters atmospheric wind flow and, ultimately, large-scale weather patterns.
El Nino's latest incarnation has affected the weather on three continents. Scientists have linked the phenomenon with torrential rains in western South America, floods in California and the Midwest, drought in Australia, and the occasional blizzard in the eastern United States.
Virginia, say the experts, usually escapes most of the Child's wrath. But El Nino does affect the flow of the subtropical jet streams that, like giant conveyor belts, send storms tracking their way up the coasts of the Carolinas and Virginia.
``During an El Nino, the Southern states are wetter than normal, from roughly November through March,'' said Vernon Kousky, a research meteorologist with the National Weather Service's Climate Analysis Center in Washington. ``This is an average. It doesn't necessarily mean floods or nor'easters.''
Indeed, according to data supplied by the Southeast Regional Climate Center in South Carolina, this winter the weather in Norfolk has been drier and warmer than usual. Average monthly temperatures in December and January were both more than six degrees above the norm, while rainfall was roughly half of what was expected.
So far, February has seen much lower temperatures, more than five degrees below average. Still, it has been dry: less than a third of an inch of rain reported, roughly an inch below normal for this year. Only Roanoke, in southwestern Virginia, has had a wet winter, with almost double the amount of expected precipitation.
None of this surprises the state's climatologist. Be careful of predictions, warns Patrick J. Michaels. In general they may be on target, but can miss a lot of territory in between.
``You cannot explain this or that day's weather as a function of El Nino,'' Michaels said. ``First of all, El Nino is not all that influential on the weather of the southeastern United States. It does affect the average temperature or precipitation of large regions. But the average is a pretty meaningless quantity as far as day-to-day weather is concerned.''
El Nino was so christened by Peruvian and Ecuadorean fishermen, who noticed a Christmas-time warming of coastal waters in western South America. In some years, the warming was especially pronounced. During such times, heavy rains would lash their villages and crops, and swell streams and rivers to flood stage.
It wasn't until the late 1960s that scientists began to suspect and then study the recurring El Nino pattern. It has been only within the past 15 years, as satellites began to examine the Earth's surface from orbit and computers have grown more powerful, that scientists have begun to identify the forces fueling The Child's comings and goings.
Recently, researchers in New York and California claimed to have developed computer models that will be able to accurately warn of the onset of the next El Nino. If so, large areas could be protected from crop damage and widespread devastation from flood waters.
Climatologist Michaels says not to confuse the long term - climate - with what we experience every day - weather. Climate can be modeled with some accuracy, if imperfectly, but weather is inherently unpredictable and will probably remain so.
Despite continuing improvements to computer hardware and software, forecasters have trouble seeing hours, much less days or weeks, ahead.
``As soon as predictions of extremely unusual weather appear, the extremely unusual weather patterns go away. That's almost predictable.'' Michaels said. ``Anybody can make a forecast. Being right is the hard part.'' ILLUSTRATION: Graphic
CHUCK EICHTEN/KRT
[For a copy of the graphic, see microfilm for this date.]
by CNB