CAPE

Looks like there will be at least some help in the NAO domain, but need the PNA to hang around neutral. Always a fight in a Nina.

Impressive -EPO across guidance now, so it appears we will have the mechanism to deliver some pretty legit cold beyond mid month. Seeing hints on the ens means of possible waves tracking along the boundary to our south, but no clear signal at this range.

We got us another one.

Foggy here too. Was worse last evening.

The 'new favorable pattern' concept over the last few runs on the means, from mid month forward-- a solidly -AO, a bit stronger -EPO, a little less -NAO. I'll take the slight tradeoff that tilts a bit more towards a favorable Pacific in a Nina. Looks colder too. Just don't want the EPO ridge to become too positively tilted, esp if the -NAO weakens.

Can't really compare a smoothed/course mean to a high resolution op run extrapolated out 15 days. Load h5 on the 6z op run, put it on animate, squint a little, and notice all the red in the high latitudes with vortices flying around all over the midlatitudes. That's the general look we want. The interactions and timing among these features will change significantly from run to run and result in wildly different outcomes.

A -AO/-NAO/-EPO trifecta can get some decent cold into Canada, then into the central and eastern US. In that setup, a slightly negative to neutral PNA can facilitate disturbances entering the west coast further south, instead of exclusively relying on waves coming over the top with a stacked -EPO/+PNA ridge. That could be dry-ish.

The GEFS h5 pattern over the last few runs has trended to a better overall look across the top for the period beyond mid month. Good sign.

Are these 2 statements related? LSD cloud seeding?

0.70" of rain here. Looks like a mild and murky day ahead.

This doesn't always work. The NAO will technically be negative, but not a true block. That chance is evaporating as we speak with a lobe of the Okhotsk TPV digging south and absorbing the vortex over Canada. Ruined by typical Nina wave interactions.

As it looks now, the colder air will come in behind the mid month storm, which at this point looks like a mild rainstorm. Still a week out and there are hints on the ops and ens that it could morph into something a bit more favorable, but most likely outcome is rain for our region, with upslope snow for the western highlands on the backside. Once the colder air is in place and the the thermal boundary is south of the area, there should be some trackable waves leading up to Xmas. For all the reasons we have discussed over the past couple days with the pattern evolution, the airmass- at least initially- will likely be somewhat colder than average for the EC. The Canadian model is probably too cold- it has a stronger more classic -NAO look for a time beyond mid month, quite different from the EPS and GEFS. Good news is snow climo is improving the last third of the month. Personally I am rooting for something simple- a more modest wave tracking along the boundary vs something that amps up. The key to a favorable pattern for the last half of December imo lies on the PAC side at this point. We need a -EPO, and at least a neutral PNA period. The NAO will initially be quite negative, although probably never close to the true block of our hopes and dreams, but trending towards neutral by the end of the month.

Sticking with Canada.

@mappy Here is your storm.

I looked at both MJO and Pacific jet configuration and the latter stood out as the bigger difference between the EPS/GEPS and the GEFS, and a possible reason for the disparity between the advertised patterns in the EPO/PNA space. eta- I have read his threads on EAMT and he seems very knowledgeable on the subject. All complicated stuff. My observations are via my untrained eye.

I looked at the NPAC jet on all 3 global means this morning and the EPS and GEPS were similar(more extended). Looks like GEFS may be playing catchup this time.

Seeing +Height anomalies in the HL regions(not the norm) is always better than the inverse. We have something to work with.

Go Canada!

Looking more EPS like.

Imagine what Ji is going through.

I suppose "delayed" in the sense that we won't have a more favorable pattern in place until later than guidance was previously suggesting. But you are right, we won't be getting that same pattern, because there was significant model simulation error in the interaction between important features that resulted in that outcome. That happens a lot in the LR, as we all know.

I have said this before, but in recent ENSO neutral/Nina/weak ass Nino winters, since 2016, the -NAO periods(mostly bootleg) have generally been too marginal (with stale/ Pacific origin cold) to get it to snow in the MA lowlands. Best outcomes have been in more progressive patterns during periods where the PAC was more favorable, mostly -EPO, with real deal cold air delivery. More of a thread the needle situation but it seems to work out better esp in a Nina. Need cold first! HL blocking during a CP moderate Nino has been gold- maybe we get that combo next winter, and we can see if that still works.

The Pacific is always a battle, but I also don't like the look of the NAO on the latest runs. It seems to evolve from a full lat ridge resulting from the western trough, then it tilts neg into GL, but it isn't so much a ridge at that point as it is a blob of higher +heights sitting there. Looking at the height lines they look flat, with little indication of a true -NAO dipole as we were seeing on previous runs, and ofc the TPV has exited stage left. As for getting legit cold air, I think it will probably have to come from a -EPO period..

I just looked at that. It might. In general the forcing looks weak regardless of phase. Not an expert on that stuff but that's gotta be better than having persistent convection near the MC.

Fwiw the GEFSX does get the h5 pattern very close to the look on the EPS, but later. Delayed not denied.