A winter storm will impact the Finger Lakes region Sunday evening through Monday with snow and ice.
This post is meant to be the comprehensive forecast for the winter storm. Additional updates from this point forward will be used to make slight adjustments and to track the progression of the storm. These future updates are unlikely to encapsulate the full spectrum of impacts from the storm in the same manner as this post. As such, unless there is a drastic change in expectations, this will be the post to refer to and to share with your family and friends.
This winter storm will be caused by an area of low pressure that will track north through the Mid-Atlantic and into eastern New York. A strong high pressure system over the North Atlantic, off the coast of New England, will prevent a track further east.
Precipitation will spread north into the Finger Lakes Sunday evening. After an initial period of snow, most areas will see at least some sleet during the overnight period.
Snow will become the dominant precipitation type from west to east, though sleet will continue to mix in through Monday morning for eastern areas.
Monday afternoon will have gradually decreasing snowfall rates with just scattered snow showers expected by Monday evening.
The snow and sleet that fall Sunday night and Monday morning will be very wet and heavy. The consistency of the snow should trend toward fluffier, drier snow in the afternoon.
Warm air aloft is a major consideration when forecasting winter storms that track north inland and not off the Atlantic Coast, as this system will do. It has been my experience time and again that most models underestimate the warm air aloft.
This results in more sleet than expected, which greatly reduces the amount of snow that the models are otherwise showing.
In addition, precipitation amounts over the eastern Finger Lakes will be about one-third of what falls in Western New York as dry air wraps around the low and into the area Monday morning.
For several days now, I have taken the approach of an icier storm for the eastern Finger Lakes, with the heaviest snow locked away over Western New York. Several models support this idea, or even exceed my expectations for sleet mixing in.
Comments on the Snow Map
There are several fine intricacies worth mentioning in the snow map.
It is highly likely that a sharp gradient in snow amounts will set up somewhere over the Finger Lakes region. Near this gradient, the forecast is highly uncertain, as a shift of 15-30 miles would have a tremendous impact in the amount of snow on the ground.
It is not unprecedented in our region to have extreme differences in snow amounts over short areas from non-lake effect events. In my research of previous storms, I found an example from March 2018 where Elmira got 3” while Bath got nearly 18”.
The heaviest snow amounts are expected along the shore of Lake Ontario, including the Rochester area. With winds coming in off Lake Ontario, lake enhancement is likely in these areas, adding several inches onto the storm totals.
This is a long, multi-part event. Some in the eastern Finger Lakes may wake up Monday with minimal snow and be ready to declare the forecast a failure. However, several inches of snow are possible Monday afternoon as the precipitation turns back to snow. My snow map is for total snow accumulations through 7 PM Monday, which accounts for this additional snow.
Remember… snow maps are an imperfect attempt to generalize a complex natural phenomenon that has hundreds of variables at play. Micro-variations in these variables will lead to differences in snow amounts that are impossible to capture in a forecast map.
Lastly, I am not in the habit of making adjustments to my snowfall map based on the latest small tweaks in the models. I do not forecast straight from a given model but hand-draw my map based on my expectations as a scientist. Therefore, the normal variations from model to model, model run to model run do not impact my forecast. Other services that produce their snowfall maps straight from model and computer data will be issuing new maps several times, which leads to confusion and uncertainty in what to expect. Of course, if a significant change occurs in my thinking, I will adjust, but I do not publish a map expecting that to happen.
Whether snow, sleet, or a mixture of both, travel conditions will deteriorate Sunday evening and remain hazardous for the Monday morning commute. Road conditions may improve for a time in the eastern Finger Lakes Monday morning if the precipitation winds down as dry air moves in. Snow through the afternoon will keep road conditions hazardous into the early evening.
Winds throughout the storm will be light but will pick up from the northwest Monday night. Areas of blowing snow and lake effect snow showers will continue to make for areas of wintry travel conditions.
Temperatures throughout the event will mostly be in the mid and upper 20s, though temperatures may push to near or above freezing for a time Monday morning in Tioga, Tompkins, Cortland, southern Cayuga, and Onondaga counties.
Lastly, if after reading this you have questions that are specific to your travel plans or forecasting needs, please do not hesitate to send me an email or Facebook message and I will be happy to assist you the best I can.
Please continue to share this information around the Finger Lakes to help spread the word about the no-hype forecasts and services I provide. If you are able to contribute financially to Finger Lakes Weather, please consider doing so to ensure that these services can continue. Forecasting these events takes countless hours and requires a lot of effort and no small amount of stress, so your contributions are greatly appreciated.
Please note that if you have difficulty giving due to errors that I am aware of the bugs and have been working for weeks to try to fix them. Usually, using a new browser in incognito mode will allow the donations to go through.