It’s back. Maybe.The climate phenomenon known as La Nina appears to be shaping up again in the Pacific Ocean, which could mean another cool, wetter-than-normal winter in the Pacific Northwest, according to the National Oceanic and Atmospheric Administration.NOAA’s Climate Prediction Center on Thursday upgraded last month’s La Nina watch to a La Nina advisory. Forecasters have recently observed the cooler-than-usual Pacific Ocean temperatures that characterize La Nina, and the condition is expected to strengthen in the coming weeks and months, according to NOAA.The natural phenomenon would be the second straight La Nina year in the Pacific, after a “fairly strong” pattern in 2010-11, said Dan Collins, a meteorologist with the Climate Prediction Center. What that means this time around remains to be seen.“It’s not always the case that a strong La Nina leads to strong impacts,” Collins said. “It just happened to be the case that last year we had strong impacts.”The 2010-11 version churned out much more rain than usual and huge mountain snow packs in the Northwest, but little in the way of biting cold. The weather pattern also tends to produce dry conditions for the southern United States, and a repeat of that would be bad news for drought-stricken states like Texas.