I am a meteorologist from New York who has been studying and forecasting the local weather for years. I especially enjoy tracking winter storms.
By: NYCvort , 6:27 AM GMT on December 11, 2013
After our quickie light snow event today, all eyes turn to a potential bigger storm system brewing for this weekend. The main ingredient to this storm is actually spinning right off the southwest coast as we speak.
With a ridge slowly passing over top, it won’t be going anywhere fast with little flow and nothing to help push it out. That finally changes by Friday as a Pacific shortwave moves onshore and forces the southern stream energy to ride ahead of it.
In the meantime, a piece of the polar vortex will break off and a northern stream trough will dive southward over western Canada and move through the Great Lakes this weekend.
It will be the degree of phasing with this system, or lack thereof, that will be a major factor in determining precipitation type for this storm, which would impact the area late Saturday into early Sunday.
The ECMWF model certainly got my attention this afternoon, which currently depicts a major snowstorm for the I-95 corridor, while the GFS/GGEM continue to show mixing issues near the coast. The main difference in the ECMWF model’s depiction is that it shows a slower northern stream, with less phasing. This results in a dominant secondary low off the coast. On the other hand, the GFS/GGEM combo features a more progressive northern stream, with the primary low hanging tough and snow/ice inland with a mix for I-95 on south/east.
My problem with the ECMWF scenario is that there isn’t enough suppression to keep this from coming north. So even if by chance it does turn out to be correct with less phasing (which I don’t believe that it will be), a north/westward trend is still possible with a definite lack of blocking (a big problem we’ve had so far this season).
The GFS/GGEM scenario really isn’t that great for snowlovers even for the north/west suburbs because most of the snow will have to be accumulated via overrunning ahead of the storm. This is because although you’ll have the cold air at the surface, a warm layer aloft will be moving inland, and dry air looks to filter in very quickly underneath the upper level system over the Great Lakes. And this storm will be moving fast.
But a slippery mix of snow and ice accretion would be another story and definitely possible. The orientation of the high on the GFS would be interesting for some of the north/west suburbs with cold air damming and mild air easily gaining latitude aloft making for the possibility of ice.
So to summarize, at this point, I would lean towards snow changing to rain for the I-95 corridor, and the possibility for snow and ice north and west. Obviously a preliminary forecast as this is still four days out, but just a heads up for anyone who may have plans for this weekend.
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