Dr. Todd Crawford, chief meteorologist at The Weather Company said: “We’ve been monitoring the emerging La Niña event for a few months now, and have observed anomalous easterly winds in the tropical Pacific that are helping to drive the oceanic cooling that is the primary characteristic of a La Niña event.
NOAA has said there is a 50 percent to 55 percent chance La Niña conditions will develop by this fall and continue through the winter.
Dr Crawford added: “As tropical season ramps up, the atmospheric pattern associated with this new La Niña event will favour a very active season.
“Typical La Niña winters see atmospheric ridging near the Aleutians, which helps to drive Arctic air into Canada.
“The wild card is whether there will be enough atmospheric blocking at high latitudes to push the colder air masses down into the U.S. If not, La Niña winters can be unusually mild.”