Lake Snow Squalls Inbound - Winter Weather Advisories Issued
As an extremely cold air mass for this time of the year rolls over the Big Lakes, the lake effect machine looks to be unleashed tonight across portions of Western and Central New York.
In advance, the National Weather Service has issued Winter Weather Advisories downwind of both Lake Erie and Ontario including Monroe and Onondaga Counties.
The difficulty with lake snow forecasting
Unlike what we saw yesterday with a large scale "system snow", lake effect snow can be VERY difficult to predict because the phenomenon involves processes that are much smaller in scale. These "mesocale" phenomenon which include areas of surface convergence and the release of latent heat over warm waters is generally smaller than the grids of the models trying to predict them. With that being said, these models can give us some ideas of what what the lake might throw at us. Here's a look at the latest (18z) run of the 3k NAM...
These squalls are driven by the difference in air temperature (which will be record cold tonight) and the surface temperature of the lakes which is relatively very warm this time of the year.
The exact path and strength of the wind (streamlines) also have a lot to do with the placement and intensity of lake effect snow squalls.
So how much are we talking about?
As mentioned, it is very difficult to precisely locate where these lake snow bands will set up and duration/intensity. With that being said, here's a look at the last two runs of the 3k NAM...
Notice much of the area see's less than an inch... both model runs agree on that. However, in the most intense bands, especially in the prior run (12z) shown on the above left, you can get some pretty intense, but very locallized accumulations. Notice the area of 6+" over Southern Wayne County.
So what do I think?
I think that snow is likely and will accumulate for much of the region between Rochester and Syracuse, also down into the finger lakes. The devil is in the details of course, so at this range the best we can do is bound an area that is most likely to produce the snowfall with broad ranges. Currently, I think the highest likelihood of seeing more than an inch, perhaps locally several, is across the more typical favored areas for these types of events including Monroe, Western/Southern Wayne, Northern Ontario and into portions of the Central Finger Lakes where up to three, possibly four inches will be possible.
Record Cold Tonight
Regardless of how much lake snow you pick up, the cold will be for real with record breaking low temps expected with some even bottoming out in the single digits!
The current record for Rochestrer is 17 degrees set back in 2013. Tonight the city could drop into the lower teens. Ouch!!
Lisa and I will be tracking the lake snow as it arrives with the latest in tonight's edition of WxLIVEat845. See you in then!