PACIFIC STORM TURNS UP HEAT ON FORECASTERS WINTER CHILL EXPECTED TO CONTINUE.

Byline: Robert Monroe Staff Writer

Enjoy today's clear skies and snow-capped mountain vistas while you can because another cold and wet storm is bearing down the Pacific Coast on the Los Angeles area.

After a day of chills and on-and-off rain, forecasters said today will be mild, but that more wet, frigid weather is expected Wednesday, with temperatures barely breaking the mid-60s, as part of another in a series of powerful storms that are perplexing forecasters hits the region.

``They're much trickier forecasts, and they kind of make you earn your pay as a forecaster,'' said Kelly Redmond, the National Weather Service's regional climatologist for the Western United States.

Forecasters had expected La Nina to deal the region a dry winter, but its signature high pressure system has been on the decline, allowing the storm-generating jet stream to reach Los Angeles.

The fluky weather is a national phenomenon. The East Coast and Great Plains are enjoying record high temperatures and sunny days more appropriate for June. Redmond said such a yin-yang relationship between East and West Coast weather is typical.

In Los Angeles, high temperatures today through Friday are expected to range between the 50s and mid-60s. Low temperatures are expected in the low 40s.

The storm dropped 0.04 of an inch of rain downtown between 4 p.m. Sunday and 4 p.m. Monday, and scattered showers left amounts measuring from 0.02 in Van Nuys to a halnch in Thousand Oaks.

As of Monday, Los Angeles area rainfall was about 2 inches below normal, but catching up quickly.

Downtown Los Angeles had received 9.32 inches of rain this year as of Monday, nearly reaching the seasonal average of 11.51 inches by the same date. This time last year, the city had only seen 4.28 inches fall.

The NWS said the storm that dropped snow levels to 1,500 feet early Monday will be gone by today but that another storm is on deck and due to arrive Wednesday.

``We're just getting a series of these every two to three days,'' said NWS Weather Specialist Stuart Seto.

Snow blanketed the Antelope Valley with as much as 4 inches of snow closing schools and blocking roads from Canyon Country to just above Mojave.

Children and staffers alike took the day off at Acton, Hughes-Elizabeth Lake and Tehachapi schools because of ice and snow. St Mary's School in Palmdale canceled classes Monday morning after more than half of the pupils stayed home.

``The main roads were frozen over and there was a significant amount of ice,'' said Don Banderas, superintendent of the Acton-Agua Dulce Unified School District. ``We have to send our buses on those frozen roads - and we have some

interesting terrain out here.''

Snow flurries and black ice - invisible sheets of ice on the pavement - were blamed for a number of minor collisions, including two on Highway 58 near Mojave and at least three on the Antelope Valley Freeway between Rosamond and Lancaster. All were single-car incidents with no injuries or minor ones.

The California Highway Patrol recorded 242 highway crashes in Los Angeles County between midnight and 5 p.m. Monday, but none was serious, Officer Karen Faciane said.

Exactly why the jet stream has moved south is a subject of debate among climatologists and meteorologists.

The train of storms crashing into Los Angeles are the result of low- pressure systems that spin off from the jet stream, meteorologists said.

These cold systems add snow and hail to the mix when they collide with warm air rising from the ground. The encounter causes cold air to swoop earthward, chilling precipitation enough to turn rain to snow.

Bill Patzert, a Jet Propulsion Laboratory scientist who predicted this would be a dry La Nina winter, attributed the wetness to changes in a longer-term weather pattern known as Pacific decadal oscillation. The pattern translates to decades-long periods of generally wet weather followed by decades of generally dry weather.

This might be part of a rough transition period between the two trends, said Patzert, who nonetheless expressed surprise at an extremely wet February.

``All my forecasts are going in the toilet,'' Patzert said. ``The cold has been correct in the forecasts but not only me but the National Weather Service hadn't expected so many cut-off lows,'' he said, alluding to the spin-off low-pressure systems.

But Redmond said such aberrations are fairly common in La Nina years, which have taught climatologists to expect the unexpected.

``It doesn't mean necessarily unmitigated dryness year after year,'' he said, noting that a freak storm dumped several inches of snow on Southwest mountain ranges on April Fools Day 1999.

``La Nina winters have a kind of weirdness to them,'' Redmond added.

RAINFALL TOTALS

Rainfall this season...........9.32 inches

Average rainfall to date......11.51 inches

Last year's rainfall to date...4.28 inches

(Measured in downtown Los Angeles)

CAPTION(S):

chart

Chart: RAINFALL TOTALS (see text)