Phil

El Niño can do that. Though usually it’s a 2nd half of winter thing more so than early on.

00z GFS is much worse if you want a SSW. But it seems to be having a hard time with this regime so, shruggie.

Clarification: 1930/31 was the strong niño, not 1931/32.

Eric Webb’s reconstructions are the best and most rigorous I’ve seen. You’ll have to scroll down a bit. https://www.webberweather.com/ensemble-oceanic-nino-index.html

1919/20 was a weak niño, yes. Easier for subseasonal variability to project onto the pattern.

1929/30 was a weak niño. 1931/32 was a strong niño.

Yes into mid-month, then another anticyclone breaks into Alaska/GOA 3rd week of the month, shutting off the spigot in BC/WA. But could be a ULL left behind near CA/OR, augmented by the STJ. Just not sure if it’ll be offshore or near the coast/inland.

The last thing I’d catch feelings over is the D10 18z GFS. I’m not desperate enough to look that far. (yet).

True. Though tbh I’m not very impressed with the pattern or the ensemble trend. The -PNA/-NAO keeps disintegrating and getting pushed back, with the El Niño/LP regime manifesting more consistently (esp in terms of the run-to-run change).

Looking at the 18z GEFS mean, you’d think so. Just a tad different.

All I did was answer a question. What do you want, a fucking novel?

The warming is caused by adiabatic compression as pressures rise within the weakening vortex. What “matters” more than anything is how the PV is affected structurally. Is it a wave-1 (displacement) SSW? Or is it a wave-2 (split) SSW? And is the vortex (or daughter vortices, in the case of a split) displaced well off the pole, with high pressure taking over (hence a reversal in zonal winds)? All of that matters more than the warming itself, which is a result of mechanical perturbation by wave activity.

Getting more real.

Statistically that’s actually the best possible scenario because every El Niño following a multiyear La Niña/snow drought has delivered a big winter. At least going back to the mid-19th century. And probably before.

I wouldn’t say that. We’ve had big snows with troughs over PNW too. The 500mb pattern matters less than regional synoptics..we need a system to phase and track to our south. The pattern structure doesn’t need to be perfect, but the timing definitely does. Important difference.