Thirsty State Casts Weather Eye to Winter

Where I grew up, in Tennessee, weather was a very different thing from what we get in California. Tennessee weather was the source of considerable surprise. We had the occasional tornado and whole seasons of dark, violent thunderstorms.

This was continental weather. In summer the thunderheads would gather quickly, as if from nowhere, and turn day into dusk. The smell of the city would change to a muskiness, even before the rain hit, and we knew we were being warned. These storms could tear down trees with their power and send sheets of lightning.

I remember sitting once in a Little League dugout, watching the field fill with water, wondering where these storms came from. They rolled in from every direction and seemed to lurk just over the horizon. In Tennessee, you never knew.

In California, of course, we know. Our rain always comes from the west, from the Pacific. The storms are carried to us by winds that work with such monotonous regularity as to seem idiotic. Our rain is as predictable and benign as our sunshine.

Or it used to be. California weather has turned out to have a few secrets of its own. We are now four years into a drought and facing a new winter. A new season when the rains will, or will not, come.

Never, in living memory, has any one season mattered so much to California. If the rains come, life as we know it will resume. Lawns will stay green. A daily shower will remain a birthright. If the rains do not come, California will enter a new age, and it will not be pleasant.

Sometime between November and March, we will all know the outcome. But this being California, no one wants to wait that long. And that brings us here, to La Jolla. At the Scripps Institution of Oceanography, they know the answer to California’s future already exists and they know where. Out there in the Pacific.

Our winter is being formed right now in the chaos of ocean swirls and atmospheric eddies. Within that chaos is a embryonic pattern--you might think of it as a fetal winter--that will eventually grow, dominate the weather of the eastern Pacific, and govern our rains. The problem is finding it.

Dan Cayan, a climate researcher here, points to an area of the Pacific somewhere off the coast of Oregon and Washington. “That’s the G-spot for rain,” he says. If a zone of low barometric pressure establishes itself there, Cayan believes, California is home free. The low pressure will pull storms toward it and then steer them straight for our coast.

But what comes before that? What puts the low pressure in the G-spot? It may be the presence of warm sea temperatures in the eastern Pacific which heat the atmosphere. Or something more complex. Records of big rain years in the past show a combination of warm and cold zones off Baja and the Southern California coast.

Cayan pulled out a weather map from 1969, one of the wettest years in recent history. There was the warm trough of ocean just below the cold trough, and the huge low-pressure area off the northwest. But even if he saw these conditions developing now, Cayan says, he could not guarantee a wet winter for 1990.

Just last year, he says, the weather patterns looked very good for rain until December. Then conditions suddenly reversed themselves, a high-pressure zone replaced the low-pressure zone, and our winter turned sunny and dry.

The truth is, our fetal winters have proved extraordinarily difficult to find. And making predictions in the face of the uncertainties demands a recklessness not commonly found among scientists. Jerome Namias, Scripps’ most well-known climate scientist and a man who likes the gamble, once made public forecasts each fall.

Namias suffered a stroke last year, however, and it looks unlikely that Cayan or any of his colleagues will step in to take his place. Perhaps the younger men are less willing to take the risk. Perhaps they are simply more mindful of their fallibility.

Meanwhile, we will wait and watch. In Tennessee, if one season turned dry we could always hope to make it up the next. In that way, a poor summer could be balanced by a wet autumn, and vice versa.

Not so with us. We have only one chance per year, and that chance is coming. By November, I suspect we will all be converted to weathermen. We will look out the window each morning and will not need the Scripps Institution to tell us whether our simple, monotonous rains have come home.