I don’t know about you, but some of the models sure are, and they have been for a while. Let me start off by saying that next weekend’s potential storm is a very different game than the one last weekend. For one, the pattern is simpler. The pattern with last weekend’s storm was crazy with a mess of features all over the place, and the models just didn’t know what to do with them. This time around, the stronger ridge out west is going to be a hindrance factor to any energy trying to get over it, and we also don’t have the messy polar vortex over southern Canada to deal with. I really don't think we’ll see drastic flip-flops with this as we get nearer to the event—I have a feeling the models will gradually converge on a solution over time.
The models have been consistent in depicting a well-developed piece of Pacific energy coming into California by mid-week. The energy from last weekend’s storm will become a strong 50/50 low later in the week. This will help to suppress the storm. So I guess even if this storm was a miss, at least it will be a helping factor in our next storm! At the same time, the NAO will be rising into a very weak negative phase, which would argue for a track near the coast. The strong negative AO will provide plenty of cold air. A rising PNA index supports a stronger ridge over the Rockies, and at least up until now, the ridge depicted on the models has looked good to me in terms of both location and amplitude. There is relatively good pattern agreement for this point in the game between the models. In fact, the new 00z/21 GFS and GGEM models that just came out show a major hit.
Now for the bad stuff. Even though the operational GFS has been suggesting the possibility of the storm tracking inside of the benchmark, the majority of its ensemble members have consistently shown a track much farther out. In fact, what has bothered me is that as the trough approaches the Mississippi valley, it is still positively tilted. This means that it will still be digging at that point as the strong jet energy remains on the west side of the trough. In my opinion, this would support the ensemble idea of a track farther out to sea. Also, every time I look at this storm on the models, it seems to be pushed back a little. Not only does this make the idea of children waking up and seeing snow outside like a wonderful classic Christmas morning less likely, but it also makes me question that while everything is getting backed up in the east—what is happening back west? If there was nothing to be learned from last weekend’s miss, it was at least a good reminder that we are in a full-fledged La Nina pattern, with a progressive jet. So while we’re looking at the addition of Polar energy here in the east blocking everything up, we need to continue to realize that the Pacific jet is waiting for no one out west. So while the ridge axis may be in a good spot initially, additional La Nina driven fast Pacific energy feeding into the west coast will be attempting to push it father inland. This is how the storm could end up missing us to the south and east. The 12z/20 Euro shows a raging Pacific jet pushing the ridge well east of the Rockies by Sunday, and I would tend to support this idea over the new GFS, which holds back the energy a bit more.
So we have the good and we have the bad. Despite the bad points, I like the overall set up for this storm, and I have from the beginning. I think this storm does have a decent shot right now, and I for one will certainly be monitoring it over the next couple of days as the features come into better agreement. I don’t think this is going to be up in the air right up until the end like the last one, though, for the reasons discussed above.
Have a great night,