Details for Sunday’s strong storm in the Finger Lakes

Everything you need to know about Sunday’s significant storm system focused specifically on the Finger Lakes.

4:30 pm Saturday Update:

I don’t have any changes to my expectations right now despite the NWS upgrading some areas to a warning. Some of the areas upgraded would have been under a warning according to my forecast, anyway. Original forecasts follows:

Complex Storm Set Up

A very complex weather pattern will set up across the Northeast on Sunday, setting the stage for a powerful storm system.

This storm will start as two different systems that will track into the Great Lakes, one from the Great Plains and the other from Canada. These two systems will interact and merge during the day on Sunday while a new area of low pressure develops off the Mid-Atlantic coast. This third piece will eventually become the dominant part of the storm later Sunday into Monday.

The complexities involved with merging low pressure systems and coastal redevelopment are significant and cast a certain amount of uncertainty on the storm’s evolution.

This is compounded by the fact that, once again, temperatures both at the surface and aloft will be in that very narrow range between snow, ice, and rain, especially over the eastern Finger Lakes and Central New York.

With all that in mind, there is decent agreement among the computer models on the basic details of the storm evolution. Combined with the lessons learned in the last and previous storms, and I am cautiously optimistic that the following forecast will hold up fairly well.

Winter Storm Timeline

Precipitation should start to work into the Finger Lakes shortly before dawn on Sunday. Areas further southwest will see the precipitation first before it tracks northeast across the region.

The initial precipitation type is tricky, but will likely be a mix of snow and sleet before mixing with pockets of freezing rain. This will continue into the mid-morning hours before temperatures become warm enough for mostly rain. Again, areas further south and west will turn to rain quickest, with mixed precipitation holding on longer further northeast. Outside of the Finger Lakes, parts of Central New York may never change over to all rain.

The heaviest precipitation from the storm will fall during the mid to late morning through the mid-afternoon hours. For most of the Finger Lakes, this will fall as plain rain.

As the coastal low develops during the afternoon hours, cold air will be pulled in from the northwest. Rain will start to change to snow from northwest to southeast between 4 and 8 pm. Precipitation during this time may be generally lighter and a bit more scattered.

After 8 pm, most of the precipitation will be snow. The intensity may ramp up again as Lake Ontario adds extra moisture into the storm. Snow will taper off Monday morning, with flurries and snow showers lingering through much of Monday, but with little additional accumulations.

Winds will also become quite strong Sunday night and through Monday as the coastal storm rapidly develops.

Here is a breakdown of what to expect at different times in the Finger Lakes.

Storm Impacts for the Finger Lakes

There are two main periods of concern for the Finger Lakes. The first will be early Sunday morning when the icy mix will move into the area. Road conditions may become rather slick due to the ice. Generally speaking, though, this hazardous time period should only last for a few hours.

Much of Sunday will have a fairly low impact for the Finger Lakes region as precipitation remains rains. As the rain turns back to snow in the evening, the second period of concern will begin.

The highest impacts will arguably be Sunday evening into early Monday morning. Moderate to heavy snow will fall, especially across the northern and eastern Finger Lakes.

During this time, the wind will also gust between 35-45 mph. A few higher elevations may gust as high as 50 mph. This will create significant blowing and drifting of the snow in addition to poor visibility.

The higher elevations of the eastern Finger Lakes will see the highest snow totals, possibly approaching double-digits. Most of the remainder of the region will see a few inches, while the Southern Tier has the lowest chances for significant snow.

Most to all of the snow shown on the snow map will fall between 7 pm Sunday and 7 am Monday.

Again, with a storm this complex, there is a certain amount of inherent uncertainty. A temperature difference of a couple degrees could totally change the storm evolution.

Continue to monitor the forecast throughout Saturday for updates, and be prepared for changing conditions throughout the day on Sunday and into early Monday.

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