Checking in on the weather from my perch in Denver, Colorado, I see we have another potential storm threat to disect for 5-6 days from now, for this weekend, in the eastern U.S. Once again, among the major computer models, it is the European blowing the horn loudest (what in the world happened to this model?). I'll post a couple of maps here, but I almost feel like my analysis resembles a broken record, as the same concerns exist for this possible storm that have existed for every threat this season. Anyway, here is the Euro's upper air map for Saturday morning:
I have drawn in a few features here. The red line in the middle of the U.S. is the feature that is our possible storm. I also drew in two other shortwaves in the northern stream up north, and the blue arrow is the northern stream itself. Notice the southern piece has "detached" from the northern stream flow. That allows it, according to the model, to slow down and "cut off" in the East, turning into a potential big late season storm. Here is the forecast map for Sunday morning off the Euro model:
The same features are outlined, and you can see the northern stream is still well north of the southern piece that it cutting off in the East. This is not something that has been able to occur all season, and frankly should not be trusted here. I see three scenarios here, and 2 of the 3 basically turn this into a non-event as far as any chance to turn into a large snowstorm.
1) The Euro model is right and we get the storm, as it is able to detach from the northern stream and cut off in a perfect position with just enough cold air... again leaning against this right now though
2) Look back at the 1st map, and note the shortwave (in red) almost directly north (actually north-northwest) of the system that is supposed to become the storm. What if the flow is again going to verify faster, and this piece is a little farther east, and can drop down and merge with the southern stream feature (most recent GFS actually showed this)? Then you get a system that cuts inland and brings rain to the East, though could be a nice snowstorm for the Great Lakes region.
3) The flow is faster, but we don't get the merging of systems (or phasing), so the southern piece is free to slow down. But the dominant northern stream crushes any ridging in the Rockies more than the Euro shows, thus any cutoff in the eastern U.S. is weaker and farther north (disconnected from major cold air source as well), or just gets pushed out to sea. This solution might be able to bring some wet snow in some localized area, but wouldn't be a huge, widespread system.
Not to play Debbie Downer for snow lovers, but it is hard given the pattern to go against option 2 or 3 here. It will take almost perfect timing to get the actual solution shown in the maps above, or something close to it, to verify in my opinion. But again, any sane forecaster must throw in the fact that this is still a few days away, and in meteorology, anything can happen.
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