The possible favorable changes to the pattern concerning the PAC are initiated Day 8-10 (Roughly day 8 GEFS, Day 10 EPS) as we start to see the PV make its move eastward towards Greenland. The models have shown for awhile that the pv's influence in the N PAC around Alaska would be substantially reduced as we would see everything mostly shifted eastward. But what I have suspected for while now (because of the ambiguous looks the models have been throwing out in this region) is that we would still see a fairly significant pv presence in this area even after we saw the shift of the main PV eastward. That said I believe the models may now be starting to pick up on this.
If we look at the EPS below note that we are now starting to see strong negative anomalies and weak troughing extending westward through Alaska. This implies to me that the EPS is now possibly moving towards at lest pv associated troughing through that region, if not a piece of pv actually residing in that region. Now the current look is still workable despite the flat flow we are seeing coming off the PAC given the time of year. The problem here is that is probably not the look we get if we do in fact see troughing/piece of pv located close to or through Alaska. Chances are good that we would actually see is a repeat of the troughing extending down the west coast as we are now currently seeing and will see over the coming days. Needless to say this is the last thing we want to see for our snow chances
Now the GEFS is also picking up on the idea of a stronger pv presence/influence around Alaska as well. But note we are seeing a difference where the stronger anomalies and troughing are compared to the EPS. These features are running north of Alaska and hooking down into the Aleutians. This is a much more favorable location for this feature and one I want to see. As a result of this we are now seeing the ability for height builds/ridging to extend up the west coast into Alaska. This would go a long way in improving our snow chances. Pretty amazing when you think about it, what just the small shifting of one feature could mean in regards to our snow chances.
Now the PAC is just one part of the equation when it comes to our snow chances. Let's see what is occurring in the N Atlantic as the pv shifts.
Interestingly enough, the EPS has a better solution then the GEFS. Note that the stronger neg height anomalies/troughing are situated mostly north of Greenland. This positioning is allowing the ability for stronger height builds northward into Greenland. Considering that we typically see smoothing at this range on the ensembles we would probably see a greater amplification of the troughing and ridging as it neared in time considering what is being presented at this time. Which would be a good look for us as it would place blocking in the central and western portions of the NAO domain. But if we look at the GEFS the neg anomalies and troughing run directly through Greenland (strong +NAO). This is effectively squashing the flow and not allowing the greater heights to build northward as we see on the EPS. And given the look I don't think we could count on seeing an improvement with the heights/ridging even if we consider smoothing. Again we are seeing just a minor shift of a feature that can have a fairly significant impact.
Now if we could see a combination of what the GEFS is suggesting in the PAC as well what the EPS is suggesting in the N Atlantic I believe we would end up with a very good look through the CONUS as far as our snow chances. But we are still 8-10 days away from when all this get jump started by the pv's eastward migration so much can/will still change.