The National Weather Service in Buffalo has hoisted the entire area under a Winter Storm Warning from 7am Thursday to 1pm Friday.

rochester

Previous discussion follows…

Here in Western New York, we’ve been pretty lucky, or unlucky for winter lovers, dodging Nor Easters as a handful of them have passed well to our south and east rewriting many seasonal snowfall records across parts of the mid Atlantic region. Our luck will come to an abrupt end Thursday with shovel-able snowfall extending into the weekend.

At the time of this writing, 2pm on Wednesday, a low off of Long Island is drenching cities like Boston will heavy rain with a change over to snow well inland. The eastern third of New York state picked up a fairly good amount overnight as elementary and high schoolers alike rejoiced over school closings this morning. Many power outages are also being reported to our east. It’s a real mess for sure.

The storm mentioned above isn’t even the one we’re concerned about here as a completely new low over a thousand miles away is beginning to take shape in the Gulf of Mexico. This system will quickly evolve and begin to ride up the eastern sea board overnight and will make it all the way up to the coastal waters of Virginia by Thursday morning. It will begin to slow down as it moves further north to the Long Island area before it slams on the brakes and wobbles around a bit remaining more or less stationary. This is a recipe for extended period of significant snowfall well inland — say Rochester, NY — until it looses its momentum. One of our computer models has the low gradually moving westward and falling apart right over WNY on Sunday so we may be looking at a 3-4 day event here.

As for timing and snowfall… Light snow will develop by sunrise on Thursday. It will start generally light and easily manageable. Throughout the course of the day, snowfall rates and intensity will gradually increase. As the low deepens (central pressure falls), a large pressure gradient will set up over us allowing winds to pick up. Blowing and drifting snow will be a huge concern. Accumulations on Thursday will fall in the 2-4″ range.

Thursday night into Friday morning is by far the period to expect to see the biggest snowfall amounts to fall. Model guidance shows large amounts of QPF (Quantitative Precipitation) in the .75″-1.00″ range across the area. A general rule of thumb for this type of snow is usually 10:1 for snow:QPF. There are no obvious reasons not to stick with basic rules of thumb with this storm. With that said, another 5-9″ of fresh snow is likely Thursday night into Friday morning.

More snow will come Friday, especially early in the day. We’ll see another 1-3″ during the day Friday before steadier action tapers to passing snow showers.

Not out of the woods just yet. As the system remains quasi-stationary, it will still generate more light to moderate snowfall for Saturday. As of now, snowfall amounts will be in the 1-2″ range, but could go up as Saturday approaches.

Temperatures from Wednesday to Sunday will hardly fluctuate from day to night and day to day reaming in the low 30s. This will allow the snow to be on the dense side which may leave a few backs sore by Sunday.

All in all, be prepared for a good 48-72 hour period of more or less constant snowfall. By the end of this event, many locations will exceed the one foot mark. I want to clear one thing up right now that has been damning to meteorologists for years when it comes to snowfall amounts. Usually, many people think we over forecast snowfall amounts, but the truth is, as snow falls, it compacts on the ground making it appear there isn’t as much snow. Also, sublimation helps to erode things away.

If anything goes of course, I’ll update as needed.