Winter is still several months away, but a brewing El Niño could mean the Northwest is in for a mild one, federal forecasters said Thursday.The National Oceanic and Atmospheric Administration’s updated outlook pegged the chance of an El Niño at 80 percent by this fall and winter. The weather phenomenon often brings warmer and drier conditions to the Northwest. La Niña winters, by contrast, tend to be cooler and wetter. But neither is a guarantee.Above-normal temperatures in the Pacific Ocean suggest El Niño is on the way this year, said Mike Halpert, acting director of NOAA’s Climate Prediction Center in Maryland. But scientists will be looking for other climate patterns in the coming months, and should have a clearer picture by the end of this summer, he said.“The strength of what this becomes is really an open question at this point,” Halpert said.The Northwest hasn’t seen an El Niño winter since 2009-10. That was followed by back-to-back La Niña years. Last year, a neutral winter — with neither pattern present — delivered a mixed bag that included a bitter cold snap in December and a blast of snow and ice in early February.In Portland, the local office of the National Weather Service keeps tabs on extended predictions. But forecasters there deal more in the immediate day-to-day range, said meteorologist Liana Ramirez. That’s part of the distinction between climate (long-term) and weather (short-term), she said.