stadiumwave

It's the combo of that & +IOD. Now, good news is +IOD is forecasted to weaken by most guidance. So, we'll just have to wait & see. Weather is never about just one thing.

If you want to worry, this is your worry:

My take away is it simply weakens the PV...for now. I will say I would rather it happen now than let's say early November. Now if occur it occurred again in a November or a December...great! Now it certainly can temporarily affect the pattern. But as far as it meaning anything for winter I don't think we could say it does. What the PV actually does has its greatest effects mid-december on whether for good or bad.

GEFS Ensemble Mean splits the strat PV at 10mb & 50mb on Day 11 The plot certainly thickens now. Pinatubo & Tonga were much different in what they spewed out. With Tonga being almost totally underwater it's largest effect will be the massive amounts of water vapor spewed into the atmosphere. We honestly don't know how much, what, or if any effect it might have. Some believe it may be a small contributor to the global spike this year in temps. Others disagree. Pinatuba spewed massive amounts of aerosols into the atmosphere that produced a massive cooling in the stratosphere that led to 6 winters of super +AO. Very few blocking episodes. Most scientists do not expect any such effect from Tonga.

I really like the strat PV showing signs of wanting to stay on the N American side. If that is a tendency this winter it would be nice. Have not had that in several winters. Obviously I would not put too much stock into it but worth noting.

This site has access to 15 day changes, if you're interested. https://cyclonicwx.com/sst.php

I don't know what impact this might have this early other than weaken the strat PV but on the European model have a split at 50mb & on its way to splitting at 10mb by day 10: 50mb 10mb

Actually you DO want 3.4 the warmest. 3 & 3.4 is fine. You don't want 1 & 2 being the warmest. While SST anomalies often indicate where the greatest forcing is in the tropics it's not always a given. That's actually what has the greatest impact on the patterns. So, overall JMA would be pretty good news if that panned out, but there's always so many variables that nothing is ever a given.

Jamstec & JMA are not the same. JMA https://ds.data.jma.go.jp/tcc/tcc/products/model/ JAMSTEC https://www.jamstec.go.jp/aplinfo/sintexf/e/seasonal/outlook.html

DJF JAN

It does not offer 2m temps. It just shows the 850mb temps. And to be honest, 2m temps are the lowest skill part of seasonal forecast models. I usually never post them even on models where they are available, unless that's all that is available. I'd rather see a 500mb mean, which usually paints the better picture.

JMA updated & like UKMET...it's about as sweet of a 3 mnth mean as you'll see. DJF JMA gives a seasonal outlook, which is the winter months of DJF above but you can't get the individual months from it. But JMA alao gives a 3 month outlook every month, so this month its NDJ. So, I can get DEC & JAN individual months from the 3 mnth outlook. DEC JAN Next month we'll be able to see FEB as well. Take away is DEC looks decent in the plains & OV. JAN is a freaking winter fantasy map!!! I'm sure FEB is as well from looking at the DJF mean. Let me add the ENSO profile for anyone interested. Key note is region 1&2 continue to fall & most of the warmer waters are in regions 3 & 3.4. Pretty strong El Nino forecast.

1870's is the benchmark. Probably the strongest El Nino going back to 1850.

1982-83, 97-98, 2015-16 had 2.0+ ONI from August to February. He's not expecting that.

Neither of those years were after a triple La Nina.

Paul means historical in the sense of where we came from, a triple La Nina. He says the turn around from LA Nina to a strong El Nino of this magnitude in the same year is unheard since 1870's. Paul does not expect an El Nino of the magnitude of 2015-16 but does expect ONI to top 2.0 for one period either NDJ or DJF.

They all have strengths & weaknesses. Personally, Iike: Euro, UKMET, JMA, & CanSips. Blend the 4 in Nov & roll with it. I'm 100% not a fam of the CFS. It's eradic. It's monthly forecast is sometimes good.

UKMET Updated: DJF, 500mb JFM, 500mb DJF, ENSO:

UKMET updated, really nice DEC-MAR DJF: JFM DJF: ENSO