1999: YEAR OF BIG CHILL.

Byline: Robert Monroe Staff Writer

If you think 1999 has been exceptionally cold, you are right.

In the San Fernando Valley, 1999 is on course to be one of the two or three coldest years since 1953, according to Pierce College weather observers. And at the National Weather Service's station in downtown Los Angeles, this year could turn out to be the coldest since 1975.

And the reason is simple: La Nina, La Nina, La Nina.

The global weather phenomenon, which maneuvers the jet stream, has left Southern California colder than normal and with far less rain, forecasters said.

``We've been freeze-dried,'' said Bill Patzert, a weather scientist at the National Aeronautics and Space Administration's Jet Propulsion Laboratory.

Last year - an exceptionally strong La Nina year - was the coldest on record in the Valley since Pierce College began recording weather data in 1949.

In 1999 it became quickly apparent that La Nina was not about to loosen her cold grip: April was the coldest on record, and June, July and August were the coldest since at least 1990 by a downright chilly 4 degrees. Throughout the year, low-temperature records across the Valley were smashed like so many falling icicles.

This far into 1999 the mean temperature in downtown Los Angeles -- derived by averaging maximum and minimum daily temperatures for the whole year -- has been 64.7 degrees. In 1975, according to NWS data, the mean was 63 degrees.

``A number of factors kept us cool all year,'' said Dave Danielson, a weather service meteorologist. ``We just had an extremely cold spring, then we had this cold water that banked up against the coast all summer.''

Think of Southern California's weather as a pendulum, with the extreme cold as a reaction to a strong El Nino weather pattern in 1997 and 1998, which had brought unusually warm, wet weather.

``El Ninos come in small, medium and large; 1997-98 was an extra large,'' he said. ``When you have a big event, it really takes a couple of years to recover.''

At Pierce, the mean temperature so far this year is 61.8 degrees. Last year, the mean was 60 degrees. Prior to that, the college had recorded a mean of 61.2 degrees in 1953.

Pierce weather observer Steve Woodruff said the final two weeks of 1999 could influence the mean temperature by as much as half a degree in either direction but probably won't reduce the mean temperature by more than three-tenths of a degree.

Still, said Woodruff, the cold is remarkable because last year and this have been as cold or colder than record temperatures set 50 years ago, before urbanization -- a process that causes average temperatures to rise -- took hold of the San Fernando Valley.

``We have the heat island effect and we're still beating the 50s,'' he said.

The cold will likely continue into 2000. La Nina, which brings Southern California cold, windy weather, is strengthening. One of its hallmarks, cold ocean water off the coast, is present with current ocean temperatures 4 to 5 degrees colder than normal.

This is not news to Shawn Schumacher, manager of Val Surf in West Hills and a surfer for most of his life.

``It's about 59 degrees so it's really cold,'' said Schumacher, 25. ``It started dropping off a lot earlier than it usually does.''

Heading into the weekend, the Valley will see more of the same: clear skies with low temperatures in the mid 30s to mid 40s and high temperatures in the mid 70s today and Friday. Wind gusts will reach 20 to 30 mph below mountain passes.

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Chart: Cold spell