Thursday-Friday snow and ice comprehensive details

Event Overview

A slow moving frontal boundary will drift through the Finger Lakes and stall just to the southeast as waves of low pressure traverse along the front.

The resultant clash between cold air supplied by a strong Canadian high pressure system behind the front and milder air pushed north by the waves of low pressure will produce periods of wintry precipitation across the area.

Winter Storm Warnings have been issued by the National Weather Service for most of the Finger Lakes Weather forecast area. As of 8 AM Wednesday, a Winter Storm Watch remained in effect for Chemung and Tioga counties due to uncertainty in snow amounts.

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The precipitation will come in two distinct phases. Phase 1 will be weaker and will span from Wednesday evening through Thursday morning. Phase 2 will be where most of the snow accumulation takes place and will start Thursday afternoon and slowly wind down during the day Friday.

The forecast confidence is reasonable across much of the Finger Lakes, but in the eastern Southern Tier, an extreme gradient in snow amounts is expected and thus confidence is very low.

Regardless of the snow amounts over this multi-phase event, periods of difficult travel are likely, especially from late Thursday afternoon through Friday morning. Travel is discouraged, especially during this time.

Event Details

Precipitation will first start to appear in the western regions this evening as some rain showers with the front still to the west. These rain showers will spread east overnight, turning to snow from west to east. Eastern areas such as Cortland, Ithaca, and Elmira may continue to see a rain-snow mix until about dawn Thursday.

With the cold air advancing into the region, precipitation should mostly go from rain directly to snow with little to no ice expected through Thursday morning. Snow accumulations by Thursday morning should be minor, with most areas seeing no more than an inch or two.

Precipitation will decrease in intensity Thursday morning and may even end at times later Thursday morning into early Thursday afternoon. What does fall will be light snow.

The second phase move from southwest to northeast during the mid and late afternoon hours Thursday. Snow will quickly become heavy, especially near the front, with snowfall rates possibly exceeding 1-inch per hour.

As this second phase moves in, warm air will try to nose its way back northward into the eastern Southern Tier. Precipitation for these areas will turn to freezing rain and/or sleet. How far north this boundary makes it is uncertain, and the boundary is likely to wobble back and forth through the night.

Just north of this boundary is where the greatest intersection of snow and heavy precipitation will take place. Snowfall rates of 2-inches per hour at times overnight are possible. The snowfall rates will gradually taper off the further north and west you go.

Heavy snow will taper to moderate snow during the predawn hours Friday. Moderate snow will continue into the mid-morning before further decreasing in intensity across the western half of the region. Further east, near the front, moderate snow will continue into the afternoon.

Most of the snow should taper off during the late afternoon or early evening Friday, but some localized lake effect southeast of Lake Ontario will be possible into Friday night. This snow is not reflected on the map, but could bring an additional couple inches to Cayuga, Onondaga, and northern Cortland counties.

Snow amounts will be around a foot for a good portion of the Finger Lakes. The best chance for over a foot will be just north of the snow-ice line in the higher elevations just south of Watkins Glen, Ithaca, and Cortland, provided these areas do not see ice.

Snow totals in the Thruway corridor will have a harder time reaching double-digits with lower snow rates.

As always, a snow map is an imperfect estimation of complex processes. It is a generalized, overall view. There will be microscale variations due to geography and internal storm processes that lead to locally higher and locally lower amounts. Use the map to get a general idea, but realize it is not gospel truth and will be incorrect in places.

I cannot stress the uncertainty in the eastern Southern Tier enough. The line between heavy snow and heavy ice will be razor-thin. Regardless, travel will be treacherous and impacts high.

Final Notes

The consistency of the snow will be variable as well. Unfortunately, the areas with the highest snow amounts are also most likely to see the wettest and heaviest snow. Fluffier, lighter snow is expected further northwest, where the cold air will be more fully established.

Winds are not a significant concern with this event, with gusts mainly around 20 mph from the north and northwest.

Quiet weather is expected behind this system with plenty of sunshine Saturday and Sunday. Temperatures will be at their coldest Sunday morning, when many areas settle into the single digits and a few pockets of subzero temperatures are possible.

This post is my comprehensive look at this event and should be the go-to post from here on out. I will have further small updates as the event unfolds. Should the forecast change drastically, I will, of course, make adjustments, but my goal is always to issue one single snow map to avoid confusion, especially with social media algorithms that do not show information chronologically.

To ensure you always have the latest information, do not rely on social media, but sign up for email notifications for my posts and download my free mobile app.

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