UPDATED 11 a.m. EST with GFS model forecast.

There is no question the snowstorm just entering New England will be a big one, and that local snowfall totals will set daily records in many locations.

But are we looking at an all-time storm snowfall record event?

There have been only a couple of New York City storm snowfalls which have exceeded 2 feet (24 inches). This one looks like it might exceed that, but with every 6-hourly weather forecast model cycle the story has changed from an epic storm, to a noteworthy one, then back to epic.

For example, last night’s GFS model run looked like maybe a foot or so of snow for NYC. A major inconvenience, but not an all-time record-setter.

Then, this morning’s higher-resolution NAM model is giving Long Island as much as 3 feet of snow by Tuesday evening, and at least 2 feet in NYC (first two graphics courtesy of Weatherbell.com):

Then, the GFS model came out with only 6-12 inches for the NYC area.

This indecision by the computer models has been going on for the last few days. All we know for sure is that the most recent forecast is usually the most accurate, but we now have wildly conflicting forecasts from the two most recent model runs. The GFS model has the heaviest snow total — approaching 2 feet — over southeast Massachusetts. Much of the rest of coastal New England is forecast to get about 1 foot of snow:

Which model is usually better? For this kind of event, the GFS model (less snow) is usually (but not always) more accurate.

Finally, we have the NWS multi-model product (using over 50 different models and model ensemble members…even using ECMWF) which comes up with sort of a best-estimate of the total snowfall (click for full-size):



Note that it is calling for 15-18 inches for the NYC-Long Island area, increasing to 2 feet around Boston.

The Long Island snowfall record was smashed on Dec. 20, 2009 when just over 2 feet of snow piled up.

In New York City, many snowstorms have produced 15 inch snowfalls, but only a couple have produced 2-foot snowfalls. In Feb. 2006, the all-time record was set at just under 27 inches. In 2nd place, December 26-27, 1947 saw a 26 inch snowfall.

High winds will make the current storm worse than normal for a snowstorm, with winds easily gusting over 30 mph in NYC, but Long Island and portions of coastal New England can expect 50+ mph gusts. In this kind of weather situation, it is also likely that lightning and thunder will occur in some locations. Most of the snow will fall tonight and early tomorrow.

What I’m dreading is for the next week reporters are going to be asking me about the role of global warming in all of this. Well, if the weather conditions were only 5 deg. or so warmer, we would be talking about a wind and rain non-event. But with colder air, it will be a major snowstorm.

Now, if you really believe global warming causes colder conditions, I have a snow-covered bridge in Brooklyn I’d like to sell you.

With the media now in full-panic mode, over three thousands flights cancelled, and Connecticut banning all auto travel after 9 p.m., it will be interesting to see how all this plays out. Say, with tomorrow’s photos of the stranded cars: