White Christmas part two...

Merry Christmas - 2"

Started snowing steady at 10pm

12-24  Euro still calls for snow, GFS and NAM limit snow to the northern parts of CT and further north.

 Buts its not that clear cut.  Nothing much has changed with the temperature layers as noted below.  GFS still has us go over 0c at 5000 feet for an hour or two.    But there is very little precip.  Below is a high resolution NAM 3k run demonstrating how scattered the precip is, and how in the end, around daybreak, we'll get our dusting.

And the result is

Now what if that line sets up before the 850 temps crash?  Or what if the models have underestimated the precip, which I think they have?

12-23 I goofed the format of the blog somehow and can't fix, so moving on to a new post.

Models are in good agreement now with having a low pressure form, and bringing it into our area for some snow.  There are really two parts.  One is an upper level disturbance, the other is the coastal low.

The inland low is formed by the upper level disturbance, the coastal by the disturbance somewhat and by the cold air/warm air battle taking place over the still warm ocean. Days ago, the coastal low was waaayy off the coast, but we would still have the upper disturbance to provide us with mood snow.  Now, the models have placed the low in a more expected position along the coast.  This results in more precip, but also more complications for areas in NNJ, LI, CT, NYC, RI and SE MA.  Whereas before it was snow or no, now its something that looks like this...

Culprit of this isn't really the ground temps, we should be cold enough north of I95 for snow.  But at the 850mb layer, or 5000 feet roughly, some warm air works in to melt the snow.  Does this completely melt the snow, does it refreeze as sleet.  I think in LI/NYC it does turn to rain, and only possibly back to snow. In NNJ I dont think the coastal low has much of an influence and the precip stays mainly a light snow.  In CT - thats the battleground.   You can see on the skew-T from roughly Monroe, CT how the ground temp is 31, but follow the blue line up and to the right and you see the red temp line poke over the blue line just a little at the 850mb white cross line.  Thats enough to change it over.  Thats how marginal the situation is. 

As a result, the SREFs only show .56 inches of snow.  I'm thinking it stays colder aloft.  Models often overdo warm air getting into CT.  And even so, its only for less than 3 hours.

Snow maps are below: