George001

The surface looks odd, there are 3 lows. I would think they would combine into one big low. The location of the rain snow line is very reasonable though considering the airmass and ocean temps. Interior areas have a really good shot with this threat, those of us closer to the coast I think will have some ptype issues. Maybe something like March 2017 or the Feb storm a couple years ago where my area got 8 inches, and 20 min NW got a foot and a half.

Euro whiffs the first threat but the h5 looks great for the second threat.

I’m still keeping an eye on it but I like my chances for the 13th better. The airmass is better by then and the blocking is in a better position.

That’s a good point, climo is more hostile now than it is in early March especially for the coast. Even my area which isn’t right on the coast has done a lot better in March than December lately. December climo isn’t favorable to begin with but It feels like climate change has made it even less favorable. The warming oceans is a double edged sword, it can help storms bomb out and give crazy amounts of snow if the airmass is cold enough, but when the airmass is marginal it makes it a lot harder, even a bit of onshore winds and the coast is cooked.

To everyone worried about thermals, I wouldn’t worry about it as long as the low location is good and the low is really strong. The low can create its own cold air, I’ve had people tell me this doesn’t happen but I’ve seen storms where it works out. March 7th 2018 was heavy rain for several hours where I live, but the low bombed out and dynamically cooled the column. The initial airmass sucked, but due to the low creating it’s own cold air via dynamical cooling I ended up getting around 8 inches of snow, with areas NW getting nearly 2 feet. That is what we will be relying on for the first threat. It’s low probability it will strengthen enough to create enough cold air to give significant snow, but I wouldn’t rule it out. The second and third threats have a better shot.

I’m not worried about the airmass, if the low location is good and the low strengthens enough the snow will come. The low will create its own cold air.

It’s the gfs so it’s probably wrong

Euro whiffs with the first storm but looks great for the 2nd one on the 13th. I’m interested to see what the EPS says.

Though I wouldn’t mind seeing the epic pattern delay a couple more weeks, that would mean my area has a better shot in the early part of the pattern as well as later on.

That’s not really true, the models have been going back and forth but the H5 looks great on the ensembles for the 13th threat. There are a lot of indies taking the low down to the 970s and some to the 960s. The interior is favored for that one, but if the low gets that deep the coast could get a lot of snow as well. I agree that the 3rd week to 4th week is when the coast will start having better chances though.

Yeah the polar vortex splitting isn’t always good for us, it can actually be bad. A couple years ago the polar vortex split to the wrong side of the globe and we had a really mild winter (2020 I think it was). I read that this year is expected to be a weak polar vortex based on the latest guidance, but no polar vortex split. I don’t even think this polar vortex event is expected to be an official SSW, just a bunch of smaller disruptions to the polar vortex instead which can be just as good.

Yeah, the models have been going back and forth on the starting date of the pattern change. I haven’t really noticed a delay, it moved from the 13th to the 10th and back to the 13th again on the ensembles. Even if it does get delayed a bit more on the models it’s not a big deal, and if anything those of us closer to the coast should be rooting for a delay to like the 20th or so.

That’s right. Lows don’t ram into massive blocks like this one.

Yeah there’s no reason to worry. As long as there is blocking it will snow. Not every threat will work out but we will have enough chances that the odds of us making it out of December without at least one big storm is very low.

Fair point, but this isn’t a run of the mill -NAO either. Also, the Feb 2018 SE ridge was even stronger than this one. Temps got up to 80 in Feb, yet the blocking still beat it down some. It took time, like this one probably will. That’s why the first 10 days or so of December are expected to be mild, and the first storm is lower probability than the latter 2 over the next couple of weeks.

I might stop by, I’m not sure yet though. I’ll have to check my schedule to see if I can make it or not.

We want the SE ridge to prevent suppression. We don’t need help with the PNA, it can snow with a negative PNA and it can snow a lot. December 2010 had a trough out west as well.

I don’t agree that the chances are lower for the first 2 systems, the ensembles have a lot of hits. OP runs are still useless. If anything the chances for the 2nd system has increased.

The ensembles still have a signal. Nothing has changed, 1st threat 10-11th, 2nd threat 13-14th, 3rd threat 17-20th. The later threats are more likely to produce than the earlier ones, but all of them have a chance.

We don’t need the pacific to be good when the blocking is this strong. The blocking will prevent storms from cutting.

I think the new upgrade made the gfs worse. It used to be ok a few years ago, but with every upgrade it gets worse and worse. The gap between the Euro and GFS has only widened, and the Canadian surpassed the GFS a few years ago as well.

The block isn’t going to just disappear, and nothing has been pushed back. The 1st threat is the 10th, 2nd the 13-14th, 3rd 17-20th timeframe. OP runs are useless this far out. They are fun to look at dont get me wrong, but it’s important to take what they say with a grain of salt, good or bad. Besides they don’t even look bad, the Canadian is gearing up a Miller B at the end of the run.

Canadian is gearing up a Miller B at the end of the run

I don’t get why people are saying we are kicking the can. The EPS has a great signal for the 12-13th. Some of the indies take the low into the 970s and 960s. Even if we do kick the can a bit it’s really not a big deal.

That isn’t possible. Blocking suppresses the SE ridge, what we are seeing is the SE ridge already in place, that’s why the blocking and SE ridge look like they are linked up initially. That’s the beginning of the pattern change, the SE ridge gets beaten down some, not completely but enough for NYC north. In Dec 2010 we had a negative NAO and negative PNA.