Happy first day of winter! Winter began officially at 5:02 am and it certainly looks like it in Central New York with a regionwide snowpack. The weather stays relatively quiet here for the next few days, with light snow chances tonight and tomorrow. A large storm system is expected to have a high impact on our local weather as we head into Christmas Eve and Christmas Day.
Low pressure originating in the Pacific Northwest will head eastward across the Northern US over the next 1-2 days. By Thursday, the storm center will start lifting northwest of our area, bringing a strong south wind to Central New York. Temperatures are expected to climb well above freezing on Christmas Eve, with temperatures generally in the 40s for most of the day. The winds continue to increase, becoming strong Christmas Eve night as a cold front approaches our area. This cold front will bring widespread heavy rainfall (1-2") to our area along with a dramatic drop in temperature. Temperatures are expected to briefly hit 50 before the front moves through, with a 30-40 degree drop in temperature in 24 hours.
The combination of freezing temperatures, wet roads, and windy conditions will lead to a widespread flash freeze. This happens when standing water doesn't evaporate but rather freezes on untreated surfaces. The freeze looks to take place Christmas Eve night and the deep freeze arrives on Christmas Day. Expect temperatures to start out on Christmas Day in the low 30s and finish in the teens. Wind chill values are expected to fall into the single digits.
As far as snowfall, there will be a changeover to snow as the front departs Central New York. The timing of when this happens is unclear at this point, and that will determine if and how much accumulating snow falls in our area. The most likely chance of accumulating snow looks to be west of Utica, where the colder air will arrive sooner. We will update you with additional information as it becomes available.
Lake effect snow is expected to develop for Christmas Day across the Tug Hill region northward towards Watertown.