storm

 Another messy winter storm is likely to bring snow, ice and high winds to Upstate New York just in time for Christmas weekend travel.

“The storm’s timing could not be worse,” said forecasting company Accuweather.

The storm starts off mostly as rain Thursday, and then rapidly falling temperatures late Friday could coat streets and trees with a layer of dangerous ice. High winds are also likely, too, which could cause power outages and even some flooding along the shores of Lake Erie and Lake Ontario, the National Weather Service said.

Heavy lake effect snow could hit Western New York and Tug Hill over the holiday weekend.

“It could be another one of these messes where we get this ice, freezing rain and snow,” warned Mark Wysocki, New York state climatologist and professor of atmospheric sciences at Cornell University. “We could have a lot of issues with travel and downed power lines.”

The storm reaches the Pacific Northwest tonight or Tuesday before barreling across the Rockies and the Plains, bringing blizzard conditions to the Midwest and snarling air travel in big hubs like Chicago. The weather service in Chicago is warning of blizzard conditions Thursday and Friday, and urging people to make plans for alternate travel.

“It’s going to impact a lot of people’s traveling plans, especially if they’re flying,” said Accuweather meteorologist Tom Kines.

Like last week, there are as many questions as answers about this storm’s impacts on Upstate right now, including how cold it gets and how fast, and how that will affect the breakdown of rain, snow and ice. And like last week, location and elevation will play key roles.

Even the snow still on the ground from last week’s storm could affect what happens this week: Snow pack keeps air temperatures colder, raising the odds of rain freezing as it reaches the surface.

The storm is several days away, so many of the details are still being sorted out as forecasters wait for more data. At this point, here’s the consensus of how the storm is likely to shape up in Upstate New York. Forecasts change, and this one will too, so be sure to check our weather page throughout the week.

Thursday: A low pressure system moving up the East Coast will bring “unseasonably warm and moist air into the region,” the weather service said. That moisture is likely to start as rain at lower elevations, switch over to snow Thursday night, and then back to rain Friday as temperatures rise.

Friday: Warm air surging in from that coastal system could push temperatures up to 50 degrees by Friday afternoon. Any precipitation that falls during the day is likely to come as rain. If it falls hard enough in areas with deep snow, it could lead to isolated flooding as the snow melts, the weather service said.