The National Weather Service downgraded Thursday the chances a La Nina will form this winter to 57%, lowering expectations for large snowpacks in the Northwest.

The service’s Climate Prediction Center a month ago put the odds of sea-surface temperatures cooling to trigger a La Nina at 60%. Two months ago, it was 71%.

Since then, however, temperatures have stayed near normal.

Tradewinds that cool the ocean and make conditions ripe for a La Nina haven’t picked up, Oregon State Climatologist Larry O’Neill said.

If ocean temperatures stay neutral, climatologists will have “basically nothing” to guide winter forecasts, he said.

“It might just be neutral this year,” O’Neill said. “We’re kind of in a wait-and-see game.”

A La Nina pushes storms to the north, causing winters in the northern U.S. to be colder and wetter than normal. Because storms move north, La Nina winters in the southern U.S. are typically dry and warm.

If a La Nina does form, it’s expected to be weak and short-lived and may not have a La Nina’s usual punch, according to the Climate Prediction Center.

Assuming a La Nina would form, the climate center in October predicted Washington and most of Oregon and Idaho will have winters colder and wetter than average, while Southern California will be warm and dry.

Southern Oregon, Southern Idaho and Northern California could go either way, according to the climate center.

Washington suffered a “snow drought” during last winter’s El Nino, according to the U.S. Drought Monitor.