Will The 'Snow Drought' End Saturday?
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Amarillo, Texas has seen more snow than Boston, New York, or Philadelphia this winter. So there's that. No breaking news to you - it hasn't snowed much. The 'biggest storm of the season' for Boston was actually in November - a whopping 2.6" of snow. Cold? Yeah, we've got that. This January has been significantly colder than last January. But every time a system comes up the coast, it warms up just in time. Thank a lack of North Atlantic blocking as a big reason for those results. But hey, it only takes one. If we managed to get a foot of snow from a storm in Boston, we'd be right back on target for average seasonal snowfall.
So that brings us to this weekend. There's still quite a high level of uncertainty about the exact track for this storm, but I'd say it at least brings the best chance for plowable snow to the area that we've seen since before Thanksgiving. I wanted to put down a few thoughts tonight, and will put together a more comprehensive blog post tomorrow night.
For those who follow the weather models, you know that they're typically in some degree of disagreement when you're several days out from a storm. This is not surprising, since there are a lot of variables going into those models which are constantly in flux. Plus, when you're a few days out, there's often poor sampling as energy responsible for storms is, many times, out over the data-poor Pacific Ocean. But there are some things to note from today's model runs.
1) The GFS is most likely out to lunch. If not, it would be quite an interesting and shocking surprise. The much ballyhooed upgraded GFS has been performing at the same level of the old version, if not worse. Its verification scores are still well behind the ECMWF since it went active, and it's the only model putting Saturday's storm out to sea. Is it possible? Absolutely. But right now I think a miss is unlikely.
2) Ensembles are certainly showing a 'clustering' of solutions on the western end of storm track possibilities. What does that mean? That the odds favor a track that's going to end up over or west of the benchmark (40N 70W). This is what I'm leaning toward as the eventual outcome.
3) We're missing some ingredients here. Again, there's no blocking. Again, there's no cold air source holding the chill in place. Temperatures are marginal both aloft and at the surface. The ocean temps are still in the 40s. The phasing doesn't look classic...almost more of a kick from the northern stream than added energy to the storm. And the overall flow is pretty progressive. These factors wave a little warning flag about going to bullish on major snowfall.
4) What I like most about the setup is a great jet structure. Strong divergence aloft should help the storm 'bomb out' or undergo bombogenesis, with its pressure falling rapidly. Such storms can help 'produce' their own air as high vertical velocities can cool down the column and keep the snowflakes in charge over the raindrops. Storms like these also tend to have banding features, and in those zones a lot of snow can fall in a short amount of time.
5) It's a quick mover. Without blocking, it'll arrive sometime Saturday morning and be gone long before you wake up on Sunday. If we manage to pump out some significant snow, the late afternoon into the evening hours look like the most likely candidates.
6) If I had to give a 'gut-cast' right now, I'd pick the 495 to 95 corridor as the best shot of seeing significant snow from this event. I'd also expect some rainfall inside 95 to cut down on totals.
All told, we're likely going to see a very strong area of low pressure near our coastline on Saturday. It may even go as low as the 970s (mb) range as it explodes out into the Gulf of Maine early Sunday morning. That's the type of system we haven't had to deal with so far this winter. I think we're going to have much better confidence in the track by Thursday afternoon and can start talking about impact/totals, or whether we're getting missed again! We'll keep you posted.
