On today's midday weather map, high pressure is centered near Montreal, Canada with a couple areas of low pressure: one over the Ohio Valley and another over Minnesota. The high pressure system was responsible for our sunny but frigid morning start. Low pressure to the south will bring thicker clouds to the region this afternoon with snow developing just in time for the evening commute.
By tomorrow morning, the aforementioned high pressure system will be located over eastern Canada with the low pressure likely positioned near Baltimore, MD. In doing so, snow will develop from southwest to northeast this afternoon. Areas from Penn Yan to Ithaca will see the snow by mid-afternoon with the Syracuse area seeing the first snowflakes sometime after 4 pm. Initially, temperatures may be warm enough for snow to melt on roads. Steady snow will likely fall through mid-evening and may even fall heavily at times.
However, as the night unfolds, warmer air above the ground will surge into Central New York and allow for snow to fall as sleet and/or freezing rain. This will first occur over the Finger Lakes region and then happen in the I-81/Syracuse sometime around midnight. Areas farther east may not see the change occur until the pre-dawn hours, if at all. Consequently, areas that receive the mix of snow, sleet and freezing rain will have the least amount of snow, thus snow accumulations will be greatest east of I-81 and lowest west of I-81. Please refer to our snowfall map for more precise details.
The snow and/or mix will likely change back to all snow tomorrow afternoon as the storm moves to our east and north. With temperatures above freezing much of the day, this will limit snowfall accumulation. Thereafter, the storm will likely to slow to leave the Northeast resulting in a brisk and cold west to northwest flow of air into Central New York. Under this regime, lake effect snow will be a concern tomorrow night and Wednesday for areas north of the Thruway. In fact, Lake Effect Snow Watches have been posted for Oswego, Jefferson and Lewis Counties where several inches of snow are possible. Expect the unseasonably cold weather and overall winter-like weather to persist through the rest of the week as spring begins early Wednesday morning.