Our next weather system in this active pattern will arrive by early Thursday morning, but its influences will start to be felt today.
The parent low is starting this morning over the Rocky Mountains of western Canada. The low will race eastward across southern Canada and will be north of Lake Huron by dawn tomorrow.
Meanwhile, high pressure over the Southeastern United States will enhance the southwesterly flow ahead of this system. A broad area of warming is already ongoing across the Midwest and Upper Great Lakes.
This warming is triggering a large area of cloudiness and unsettled weather well to our west. While the clouds will have an impact today, the precipitation will not.
Mostly thin clouds high in the atmosphere are across the Finger Lakes to start today, though a few areas of thicker low level morning clouds also exist. The low clouds will burn off this morning as thin clouds aloft increase and gradually thicken.
Sunshine will filter through the clouds this morning but will be less able to do so as the day goes on. The afternoon will probably end up rather overcast but will remain dry.
Southwest winds will blow at 5-10 mph, helping temperatures nudge upward. Look for highs to reach the upper 30s and low 40s this afternoon.
Temperatures will drop back to the mid 30s this evening but will climb back to the upper 30s and low 40s after midnight. A few rain and snow showers will also be possible after midnight, especially across the southern and eastern portions of the area.
Any overnight precipitation will be associated with the push of warmer air. After sunrise, rain will spread into the area associated directly with the low pressure as it continues to power eastward. On and off light rain should be expected throughout Thursday.
Temperatures will continue to rise with highs in the mid and upper 40s. Southwest winds will be blustery, with gusts to 30 mph. The wind will swing around to the northwest by sunset, maintaining its strength.
Temperatures will tumble back into the 30s Thursday night with pockets of 20s by Friday morning.
As the colder air rushes back in Thursday night and Friday, some thin bands of lake effect will likely develop. The bands could gain some additional support from the Georgian Bay off Lake Huron to our northwest, making for some brief squalls.
In general, though, the lake effect bands should be small enough that only select locations across the northern and eastern Finger Lakes will see snow ongoing at any given time. The band is also expected to move around, keeping accumulations in any given location low.
The lake effect will slowly dissipate during the second half of Friday as it moves north on shifting winds. Sunshine will be possible outside of the band and late in the afternoon.
Temperatures on Friday will mostly be in the mid 30s with higher elevations close to the freezing mark. Northwest winds may gust to 30 mph in the morning but will diminish through the afternoon.
Another weak system will drop southeast toward the region on Saturday. The center of low pressure will likely track across the Adirondacks, keeping most of the precipitation to our north. Still, some light snow is possible, especially in the northern half of the region. A little rain could mix in as well, with some areas reaching the upper 30s.
A stronger weather system will approach on Sunday with increasing clouds and possibly some late rain or snow. The most likely scenario is for low pressure to pass overhead or to the north, allowing temperatures to warm Sunday night.
Much of the precipitation should fall as rain as things look now, but some snow will be possible as the precipitation first moves in Sunday evening, and as the precipitation ends on Monday. It would not take much of a shift south to change more of the rain over to snow, so keep checking back for updates.
A similar scenario will unfold later in the week as another system tracks near or directly through the area. Again, as things stand now, at least some of the precipitation should fall as rain, but confidence with this second system is even lower than with the first.
A pattern shift towards milder and perhaps less active weather is being hinted at on the models for the middle of December. Time will tell if that comes to fruition.
This graphic represents an average over the entire Finger Lakes region. Localized variations should be expected.