1.10.2018 -- Get Ready to Take a Wild Ride
Moderate to heavy rainfall Thursday night and Friday. Confidence = high.
Significant to major snow storm for western/northern NY late Friday night through Saturday; significant ice / mixed precipitation to snow for central and south-central NY late Friday night through Saturday. Confidence = increasing.
A Winter Weather Advisory is up for a large portion of the North Country through 1 AM tomorrow for freezing rain. A glaze of ice is expected to occur.
A Flood Watch is up for all but the northeast corner of New York for late Thursday evening through early Saturday morning.
A Winter Storm Watch is up for all of western New York Friday evening through Saturday.
STRAP IN FOLKS.
1. As has been anticipated all week, moist, warm air is rocketing northward. As of 4:40 PM, temperatures range from 45 at Rochester to 41 at Penn Yan, 34 at Binghamton, Utica, and Watertown, to 30 at Plattsburgh. These temps are going nowhere but up over the next 36 hours. High temperatures Thursday will range from near or around 60 degrees from Buffalo to Rochester, to the mid 50s for much of the Fingerlakes, around 50 for Watertown to Utica, Oneonta, and Binghamton, to the mid and upper 40s elsewhere. Temperatures Thursday night won't drop very much as we'll continue to get pummeled by this southerly flow, and in fact, some areas may have temps continue to rise Thursday night. For Friday's highs -- this is where it starts to get tricky -- and dependent upon the evolution of our storm systems. AS OF RIGHT NOW, Friday's highs for areas... say from Oswego southward through Geneva to Wellsville will be seen early in the day -- mid 50s -- with temperatures falling through the afternoon. Temps across the central Adirondacks to the Canadian border should be in the upper 40s to lower 50s; this also extends southward along I-87 toward Albany. For the Susquehanna Region, highs may flirt with the 60-degree mark from Cooperstown to Binghamton, with slightly cooler temps in the Catskills and the lower Hudson valley.
2. For the actual weather conditions Thursday, mainly cloudy conditions can be expected with some off-and-on areas of light rain. The real "first system" doesn't begin until Thursday night.
3. On Thursday night, a "wave" of low pressure will ride the robust southerly flow across the state. This will cause widespread rain across the state late Thursday night through Friday.
The model guidance shows rainfall amounts around 1 inch to about an inch and a half, but it wouldn't be surprising to see some areas pick up as much as 2 inches of rain through about noon on Friday. (The European model paints a bullseye of 2.1 inches over the UCA/RME area by 7 PM Friday -- all liquid.) The rainfall may be enhanced also by the same "upsloping" that occurs over the Tug with the lake effect snows. There will undoubtedly be a significant reduction in the snow pack because of this system.
Expect rain to continue through the day Friday... but a transition will be beginning as a cold front starts to move west-to-east across the state. Remember we mentioned a minute ago that highs on Friday would be in the morning for WNY, and as the front moves through, look for temps to tumble into the 30s. This will also lead to a period of mixed precipitation as our second, and more significant, storm system takes shape off to our south.
As we move into Friday night and Saturday, confidence is increasing for a major winter storm across the state. The devil is still in the details, though, as we're not quite certain yet where the heaviest snows are going to set up, and where there may be a decent amount of mixed precip over CNY. The latest models have shifted the low center south and east, so that by 7 AM Saturday the European model advertises the center of low pressure over Long Island, and the GFS placing it ... well ... over the eastern tip of Long Island. Once the storm system hits the southern New England coast, it steps on the gas pedal and accelerates quickly out of here. Mixed precip changes to all snow across the rest of CNY but accumulations would be somewhat limited given how quickly the storm is expected to pull on out of here.
THE FIRST CALL SNOW MAP -- shown again by our snowmobile icons instead of numbers for now as there is still quite a bit of uncertainty with the placement of the heaviest snow... but as it stands right now, this minute, 5:11 PM Wednesday, the "zone" of heaviest snow would extend from a line from Malone, Plattsburgh, and Burlington WSW through Watertown, Lowville, Syracuse, through Penn Yan, Geneseo, Cattaraugus, Olean, to Jamestown.
The heaviest stripe of mixed precip would occur from roughly Lake George WSW through Gloversville, Utica, Cooperstown, Sherburne, Delhi, to Binghamton and Elmira.
Factors such as accumulations, placement of the heaviest snow and ice, etc., ARE HIGHLY DEPENDENT on the eventual track of the surface low. In other words, THERE IS STILL THE CHANCE THIS COULD BE A MISS. A storm track farther east, along the baroclinic zone (which is a tight temperature gradient over a constant area of pressure -- it's like a cold front but without changes in air pressure). Models aim this zone along the coast, and if our low takes an even farther southeasterly track, western NY gets just a modest little snowfall as the axis of heavy snow shifts eastward, east of I-81. If the storm tracks farther west, we would tend more to a mixed precipitation / freezing rain event for a larger portion of the Upstate, creating a spectacular mess.
Given the headlining nature of this system, we're not even going to begin to discuss the return to significant cold and lake effect snows for next week...