Terpeast

Yeah you do make a good case on this. Last year was a very strong nina in terms of MEI, though. PDO was deeply negative, so we had a -PNA firmly in place, which helped link the SE ridge with the south-based block. This year is different (most likely) so maybe this will create some new scenarios where south based blocks will actually help the MA & SE with snowstorms… IF we get enough cold air via +PNA to begin with.

Makes sense. The next thing I want to try is to break out tiers of positive AMO and see how the strength affects blocking, and then maybe project this year out because the AMO is in unchartered territory. Could it mean more suppressed tracks during a nino as the block forces storms to go under it? Could it force storms to cut as they eject eastward, or is that more of a nina thing even with strong blocking? Could it also mean that storms will be even more juiced and even slower moving as they “sit n spin”? Means someone is getting over 40” somewhere Who knows, maybe all of the above… in one season.

I found something potentially interesting. According to this dataset, the AMO is at its highest ever. https://www1.ncdc.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.amo.dat Latest AMO is well over +1 in the last several months. Latest Sept value is +1.41 If this has any actual bearing on winter, it may favor south/SW shifts to N Atlantic blocking based on a H5 regression vs AMO using 1990-2023 as the base period. Look at the gpm values in the axis... the signal is strong. Very strong. Any thoughts? Is this important to include in our winter outlooks? Or am I just going down another rabbit hole?

Since we're heading into neutral PDO territory, but we still don't expect it to go positive. PDO may bounce in the cold neutral range from here on out. So here's what a cold-neutral PDO winter looks like at 500mb. I didn't filter by ENSO or any other tele. All winters between a DJF average of between 0 and -0.5 PDO since 1950. - weak signal of an aleutian ridge and some western US troughing, which makes sense - stronger blocking signal over on the atlantic side, but may be confounded by other contributing factors like qbo, etc Take it fwiw. I've also been playing around with analog winters that followed a strong rise from deeply negative PDO. I used -1.5 as the threshold anytime between April and July preceding the following winter, and selected winters that were neutral PDO on average. It is rare for a deeply negative PDO to rise to neutral so quickly within 6-9 months into the following winter. This has only happened 5 times in the last 70 years. This year may be the 6th. Here's a 500mb composite of winters following a strong and rapid PDO rise out of deeply negative territory: This time you see an aleutian low N of Hawaii, which had to be the driver of the strong PDO rise, and it seems to have stuck throughout those winters. Also N atlantic blocking seems to be a recurring theme. Note I changed the contour intervals to get rid of the exaggerated cold bias of older analogs.

Yeah, the oct run of the euro must have been initialized when the pdo was close to -3. Last I checked, we’re within 0.5 of neutral, so I’m curious what the nov run will have to say. Maybe it’ll look more like the sept run, or maybe it’ll stick with the SW trough idea, or come up with something entirely different.

It was never going to be long lasting. The N pac rex block causing the -pna and the subsequent flip to cold is only going to last 5 days, so both warm and cold are going to be transitory.

I’d wait until the next euro run now that the PDO is close to neutral, and the rex block may further cool the ssts north of hawaii. The october run is not a bad look though. And the warmth late october, while I’d have preferred it to happen in november, is not entirely unexpected. The same rex block that should reinforce the pdo rise is the cause behind the upcoming warmth, and it’s only temporary. it doesn’t mean that we’re still in a la nina or that a ratter is incoming.

Leftovers from a triple nina? If we’re going to get this, better in Nov than mid winter

For our winter purposes, I like it where it is now.

Pretty brisk and gusty but otherwise nice. 60

A lot of it makes sense, and I agree in large part. But his claim that the autumn has been “much colder” than in recent years doesn’t jive with what I observed last year vs this year. Last autumn was colder. This autumn has been near to slightly above normal. He’s not wrong about the number of coastal storms lately, though.

PDO is close to neutral now. Troughing north & nw of Hawaii helped bring the PDO up a bit: And as a rex block establishes itself, the trough should deepen due n of Hawaii, which will have an impact on the ssts there. Could this be the thing that finally breaks the nina-like base state in the mid-latitude pac? Time will tell.

Shared this in the main nino thread.

I have a feeling that they don't really dig as deep into this stuff as we do, and just lean on nino climatology by default. And they're usually not that far off the mark. Makes me wonder whether factoring in the spaghetti soup of teleconnections is, for lack of a more polite term, a waste of time. (I'm guilty of this too)

Do you mean last month’s MEI being 0.6? I expect the MEI to come in higher this month, but you’re not wrong in that some people read the same dataset and conclude that a strong/super EP nino is on the way while others (including myself) see a more moderate event based on forcing and sst gradients between tropics and mid/high latitudes. Yet others look at the same data and conclude that we are not really in an el nino event based on atmospheric response.

My outlook will be done in november

Interesting, any diagrams you could share here? I thought I might have seen something that alluded to this, but I'm atrociously forgetful when it comes to links

Trending in the right direction the past 15 days. Still negative, but not extremely so. Upcoming rex block N of Hawaii should help continue this trend

What site are you using to run these nino3-H5 charts? I’d like to try the same, but using nino4 instead

39. One of the colder mornings so far

Hunga Tonga–Hunga Haʻapai

Not much except maybe a glimmer of hope that HTHH won’t deliver an +AO death knell. Also worth noting that after a SSW (and/or Strat PV split) back in Feb, mutiple HL blocking episodes ensued for several months afterward lasting through all summer

While 09-10 is a good match for this year... 91-92 is also a good match, especially if HTHH's strat vapor effect is to counter the -QBO to produce +AO (which is TBD). Two vastly different results with similar ENSO/PDO/QBO setups. This winter will be decided by the polar domain, I am certain of it.

As far as the missing cold subsurface in the WPAC, maybe that's not a bad thing? It could indicate a multi-year nino instead of a one-time blast before a return to la nina conditions. Your guess is as good as mine.