Quiet Friday leads into sloppy weather Saturday

finger lakes weather forecast friday december 17 2021 sunny clouds wintry mix saturday
Snow, sleet, and pockets of freezing rain will make travel tricky Saturday, especially in the morning and midday hours. [Photo by Gwen Moshier]

Wintry Mix Saturday

An area of low pressure will approach the area tonight and pass south of the region tomorrow, spreading a mixed bag of precipitation types across the Finger Lakes region.

For today, though, there are no major concerns from the weather, provided you have your sunglasses handy. Skies are starting out clear and will be dominated by sunshine for much of the day. Only some thin clouds during the latter half of the afternoon are expected.

It will not be as warm as yesterday, thanks to an overnight cold front, but temperatures will still run noticeably above average. Most areas should get into the mid 40s today with some low 40s in the hilly areas.

Winds will be generally from the west with speeds of 5-10 mph. The wind will swing to the northwest late, and then to the north, northeast, and finally east overnight. Clouds will also thicken, holding temperatures between 30-35 degrees for the start of Saturday.

Snow will start to develop and move into the area around sunrise, though it may struggle to reach the ground in the dry air. As precipitation increases in intensity and coverage, it should easily overcome the dry air and reach the ground within a couple hours of sunrise.

From here, the challenge is figuring out precipitation types. Almost always, the models underestimate the influx of warm air in these scenarios. As such, my forecast may vary from other sources. It is important to remember that the difference between snow, ice, and rain is a mere degree or two over the span of several thousand feet of atmosphere. Add in the complex terrain of the Finger Lakes and knowing the dominant precipitation type at every location becomes almost impossible.

That being said, here is how I envision tomorrow playing out.

The period of snow will be brief, and the southern half of the region may only see a few flakes before turning over to some sleet. Higher elevations have the best chance for seeing freezing rain, though only a light glaze is expected.

During the late morning to early afternoon, snow will start to change to sleet across the northern areas, even north of the Thruway. Further south, sleet will begin to turn to rain, especially in lower elevations.

By the mid afternoon, any remnant icy precipitation should be limited to north of the Thruway, while the rest of the region sees rain showers.

This is a more aggressively warm forecast than the models. In the event the models get it right this time, which I have no reason to believe they will, here is how they differ:

Areas north of I-90 generally stay snow with perhaps some sleet mixing in late in the storm. Snow accumulations of 2-4 inches would be likely. South of the Thruway, an icy mix of snow, sleet, and freezing rain holds on through the early afternoon, only changing over to some areas of rain late in the day.

Either way, travel will be sloppy until precipitation turns over to rain. This means the morning and midday especially will require extra travel time and due caution.

Winter Weather Advisories will be issued this afternoon by the National Weather Service. These advisories will likely contain information that more closely matches the models.

It can be frustrating to receive different weather information from different trusted sources. However, my job is to bring the best forecast that I can make, and my experience over the years has taught me time and again to not trust the models in these situations. We will see if tomorrow adds to that databank, or if it ends up an outlier.

This is science. It is not clean and tidy. Outliers sometimes happen, and that is why I have attempted to explain both what I think will happen and what else is possible. Hopefully, this will give you a fuller understanding of the weather and reduce the frustration.

Please feel free to reach out to me if you have questions specific to your travel plans tomorrow. This is another unique service that I am able to provide that you will not find anywhere else.

finger lakes weather 7-day forecast friday december 17 2021
This graphic represents an average over the entire Finger Lakes region. Localized variations should be expected. Click to enlarge.

Another Quiet Stretch

Behind this system, a spray of light lake effect snow showers will develop Saturday night and into Sunday as colder air moves in. The snow will gradually diminish on Sunday. Most areas should see little or no accumulation.

High temperatures on Sunday will mostly be in the mid and upper 20s. A few lakeshore areas may manage to hit 30 degrees. A chilly night will set up Sunday night as skies clear. Monday morning temperatures should be down into the teens for most areas.

Monday will be sunny with some periods of clouds mixing in. These clouds may be thin enough to allow the sun to filter through, anyway. Temperatures will rebound from the cold start to top out in the upper 30s.

A couple of weak disturbances will pass nearby on Tuesday and Wednesday. These systems will not have much energy or moisture to work with, so most areas will remain dry. A stray flurry here or there cannot be ruled out, though.

Both Tuesday and Wednesday, and even Thursday as well, will have highs in the mid 20s. Thursday, too, will have a mix of sun and clouds, but without the small chance for a flurry.

Precipitation will be more likely on Friday, but still does not look too widespread or heavy. With temperatures uncertain, this could end up as some snow or some rain.

Christmas falls on Saturday and there is at least a chance for active weather. The details this far out are too uncertain, though.

If we are going to end up with a White Christmas, the snow will have to come on Christmas Eve or Christmas Day itself.

More Information:

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finger lakes weather 7-day forecast friday december 17 2021
This graphic represents an average over the entire Finger Lakes region. Localized variations should be expected.

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Follow Meteorologist Drew Montreuil:
Meteorologist Drew Montreuil has been forecasting the weather in the Finger Lakes region since 2006 and has degrees in meteorology from SUNY Oswego (B.S. with Honors) and Cornell (M.S.). Drew and his wife have four young boys. When not working or playing with the boys, he is probably out for a run through the countryside.