Birth and Death of a GFS Eastern Snowstorm

Henry talked yesterday about the potential for a snow storm next week for the East Coast. He and Elliot also talked about it yesterday in Elliot's Weather Worriers video. I'd like to show you what's been happening during the last 24 hours in the GFS model's forecast.

First, what would cause a heavy East Coast snow this time of year? Nothing short of a Nor'easter, so we need to see a big low pressure off the coast. Here's what the GFS suggested yesterday morning in the "12Z" run:

That's a pretty decent low pressure system off the Jersey coast, which would send moisture up and around it (remember, low pressure systems rotate counter-clockwise), into the cold air (whose arrival is not in question), as the low moved up the coast, causing a wide swath of snow.

You don't have to use old-school meteorology to try to figure out what the snow amounts would be - all that collective consciousness is in the model as algorithms these days, and they produced this map, which is what prompted people to start talking about the storm (as you can imagine!)

One of the things about the GFS that you have to remember though, is that it's only one model, and it can disagree with itself as time moves forward. What you really want to see is agreement in future model runs (it comes out 4 times a day). And even more importantly, it should agree from day-to-day at the same run time (each run is slightly different due to the availability of meteorological data).

Unfortunately yesterday after the 12Z run, the model lost the storm, flattening it out, weakening it, and moving it further north in the 18Z run, all bad news for snow lovers in the mid-Atlantic and Northeast. The 00Z run was similar, and by 06Z this morning, it had lost the storm completely:

The 12Z run for today is now out, and although it has a weak low pressure system, it's still not positioned right and I think the hope for this storm may be over. The final nail in the coffin? J.B. didn't even mention this storm on his daily videos for our Pro site (I snuck a cellphone pic of him doing the videos at right in J's Breaking Weather News). But don't fret, they'll be plenty more - and the next one might just stick around on the model.

Below is the current snowfall map for the lake-effect events that will take place this weekend and early next week (white, realistically, means snow flurries with little or no accumulation).