We’ve stayed relatively quiet about a possible major snowstorm for later this week, but with some new data and the storm drawing near, it’s time to start discussing the potential for this. Just as we saw with yesterday’s major snow that never really materialized, we’re watching two (maybe even three) distinct pieces of energy associated with two different jet-streams that will begin interacting with each other early next week. The big question that will answer whether or not the Mid-Atlantic and Northeast get hit by a major snowstorm is: do these two pieces of energy phase together, and if so, how quickly?
When presented with this same question last week, there was a lot of evidence to suggest we’d have enough interaction to bring a good thump of snow to I-95, but as the storm got closer, it was obvious the pattern was too progressive to phase anything together. A week later though, and we have a slightly different setup that may be more conducive for that type of phasing.
You can see the overarching pattern that we have is set up pretty well. We have vey strong ridging out west, a deep trough in the east with plenty of direct arctic intrusion, and some blocking south of Greenland. In theory, this should allow two streams of energy to get close enough for phasing, but the real question then becomes, how quickly does everything phase together?
We essentially have two scenarios on the table. The first is that the southern stream energy doesn’t jet way out ahead of the northern stream energy, and we get interaction early on enough that phasing occurs and takes the storm near the 40/70 benchmark. For those who are enthusiasts, you’ll know that any storm system near the 40/70 benchmark usually has a good chance of bringing a major snowstorm to the I-95 corridor.
The more blocking that we have south of Greenland, and the slower that southern piece of energy is, the better chance we have at getting a solution like this to unfold. This would mean big snow potential from Washington DC to Boston, with the possibility of heavier snows falling even further west than that.
The second solution on the table, and currently the more favored among guidance, is a much later phase with the storm not consolidating until it is well offshore. This would mean a track far to the east of the 40/70 benchmark, and mostly lighter to moderate snows falling from the I-95 corridor on east. Even here, there’s a chance that all the snow remains offshore, and we don’t get much at all.
In this type of scenario, we may get a few fluffy light inches of snowfall to accumulate, mostly north and east of New York City, and then up into coastal New England. The southern stream energy doesn’t slow down enough to phase with the northern stream, and thus the storm jets off quickly and gets its act together too late to produce a big storm for the Mid-Atlantic and Northeast.
So where do we stand? What we need is for these two pieces of energy to be fully sampled by our computer guidance, and until that happens, it’s a guessing game as to which solution wins. Model guidance at the current time doesn’t have a great handle on how both the northern and southern energy will move, and thus is struggling to decide where to track the low after there is phasing (if we get phasing at all).
The other aspect that guidance is having a hard time handling is the precipitation field. This is a classic issue we’ve seen with storms just like this, and in the meteorological field, we refer to it as convection feedback error. Rather than place the low between the convection being presented, the model tries to put the low where the heaviest precipitation is. This, unfortunately, is not how it works. Let us show you what we mean.
Using the Canadian model as a sample, at 96 hours it shows three areas of heavier convection, and you can see the model is trying to figure out where to pop the low. Now it’s possible that there’s so much unconsolidated energy that a scenario like this could workout, but more likely than not, the low will form under just one of these lows. If we get the storm to develop under that middle (strongest) piece of convection, we have something closer to scenario two, with light to moderate snow hitting the I-95 corridor. If we get the storm to develop under the convection closer to the coast however, which you can see the model trying to do, we get a solution closer to scenario one. That would mean the precipitation field could expand well west, and places from Philadelphia to Boston would likely get heavy snow and strong winds.
The issue is that this convection feedback error may not be resolved until we get some mesoscale guidance to cover it, or at least until we get each energy sampled into the guidance. This won’t happen until sometime tomorrow, so for now we have to wait and do some speculating.
What you need to know at this time is that there is the potential for a major snowstorm to impact the northern Mid-Atlantic, Northeast, and New England, but it’s still too early to make any definitive calls. If we can get our two pieces of energy to phase earlier, we have a better shot at achieving scenario one. If each piece of energy does not time up right, and we see convective feedback problems, getting a widespread snowstorm along I-95 will be difficult. We’ll know much more at this time tomorrow, so check back then.