Weather forecasters are backing off their earlier prediction that La Nina atmospheric conditions would drive weather patterns this fall and winter. That means all bets are off when it comes to how — and how many — storms will approach the West Coast, advises Michelle Mead, a National Weather Service warning coordinator. The federal Climate Prediction Center had issued a “watch” for La Nina — a mixture of atmospheric and ocean surface temperatures that tends to steer storms toward the Pacific Northwest and Northern California.